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Journal articles on the topic 'Aerospike engines'
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1
Meiss, Jan-Hendrik, and Eric Besnard. "Numerical Analysis of Curved Thrusters for Multichamber Aerospike Engines in Flight Conditions." Journal of Propulsion and Power 33, no. 4 (July 2017): 1002–19. http://dx.doi.org/10.2514/1.b36332.
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Ashley, Steven. "Bringing Launch Costs Down to Earth." Mechanical Engineering 120, no. 10 (October 1, 1998): 62–68. http://dx.doi.org/10.1115/1.1998-oct-1.
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This article discusses the three federally funded projects that are underway to develop new rocket engines that can make it more affordable to send payloads into orbits. The new RS-68 propulsion system is Rocketdyne's entry in competition to power the US Air Force's new heavy-lift booster. The most ambitious of the new propulsion system designs is Rocketdyne's XRS-2200 linear aerospike engine, a seemingly nozzle-less oxygen/hydrogen powerplant that is designed to send the autonomously controlled NASA X-33 lifting body into orbit. The X-33 is being developed by Lockheed Martin Skunk Works, Palmdale, CA. The key for new launch vehicles, whether they're expendable or reusable, is to get the costs down. The article also highlights that the payload that can be lofted by a launch vehicle depends in large part on engine performance and the ratio of propellant to structural weight. Bell nozzles are designed to offer the best compromise of shape and length for a vehicle and flight path. Rocketdyne's R-68 engine is to be 17 feet tall and 8 feet wide at the base. The key to the R-68 engine design was the selection of hydrogen as the propellant rather than kerosene.
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Lewitowicz, Jerzy, Mirosław Kowalski, and Andrzej Żyluk. "Modern Diagnostics of Aircraft Gas Turbine Engines – Some Selected Issues / Nowoczesna Diagnostyka Lotniczych Silników Turbinowych - Wybrane Zagadnienia." Journal of KONBiN 29, no. 1 (December 1, 2014): 33–40. http://dx.doi.org/10.2478/jok-2014-0004.
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Abstract In aeronautics, the question of maintaining the highest possible level of flight safety is the most crucial issue. This is the reason why the scientists, engineers, and aerospace/aviation engineering staff keep searching for ever newer and more reliable methods of increasing the safety level. Therefore, new methods - primarily nondestructive ones - to diagnose aircraft turbine engines are looked for. These methods are expected to prove useful for the real-time monitoring of actual health of the engine and its assemblies. The paper has been intended to outline the most recent methods of diagnosing aircraft turbine engines, including the computed tomography methods as applied to assess health/maintenance status of turbine blades, for the phase mapping of increments in the engine’s rotational speed, to diagnose health/maintenance status of the compressor’s 1st stage rotor blades in pure jets. Other methods discussed are, e.g. vibroacoustic and tribological ones
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Zhou, P. L., and Y. Q. Qian. "Development of a modified diesel engine cycle." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 212, no. 2 (February 1, 1998): 145–50. http://dx.doi.org/10.1243/0954407981525867.
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This paper presents an investigation of a novel type of diesel engine cycle, an approximate constant pressure cycle. The prototype engine is called the diesel engine with oil cushioned piston (DEOCP). In contrast to conventional engines, the DEOCP has a variable cylinder volume which is controlled automatically by the engine's cylinder pressure. The variable cylinder pressure is achieved by inserting a hydraulic cylinder into the engine's piston rod. The engine cylinder pressure is thus self-controlled and an ideal constant pressure cycle can theoretically be achieved. Computer simulations and engine tests have shown that the DEOCP distinguishes itself with high cycle efficiency, improved low-load performance and good starting ability. A detailed theoretical analysis and test results are presented in the paper, as well as a discussion of existing problems and possible further developments. Development of the diesel engine with oil cushioned piston could break the limit of cycle efficiency of conventional engines, hence opening a new avenue for diesel engine development.
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Glowacki, Pawel Jan. "Aircraft piston engines on-condition exploitation." Aircraft Engineering and Aerospace Technology 90, no. 7 (October 1, 2018): 1095–103. http://dx.doi.org/10.1108/aeat-01-2017-0042.
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Purpose Currently, in many countries, aviation safety regulations allow piston engines exploitation above Time Between Overhaul (TBO) recommended by manufacturers. Upon fulfillment of certain requirements, which are already included in the manufacturers’ documentation, TBO extension is granted. National Aviation Authority has approved exploitation of piston engines to something like quasi on-condition maintenance, which has no technical proof behind. This leads to the conclusion that the current, simple way of the engine’s life extension is not the best solution for maintaining flight safety. Aircraft piston engines TBO extension requires changes in the current exploitation system. Design/methodology/approach The paper provides methodology for aircraft piston engines on-condition exploitation based on engine flight parameters (from cruise and takeoff) and engine oil particles analysis. The paper describes a method of diagnostic limits for certain engine parameters and elements in the oil assignation assuming that they come under rules of normal distribution. Findings It has been found that piston engines installed on maximum takeoff mass <5,700 kg class aircraft are the second biggest contributor as a source of aviation events, thereby having a significant impact on aviation safety. Engine flight parameters and elements content in the oil meet Gaussian rules. Practical implications Introduction of the engine on-condition exploitation into operation practices reduces the operator’s engine direct maintenance cost and increases technical knowledge of the employees and has a positive impact on flight safety. Originality/value It is the first scientific description in Poland, which proposes an empirically proved methodology of the aviation piston engines on-condition exploitation.
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Clifton, David A., Peter R. Bannister, and Lionel Tarassenko. "A Framework for Novelty Detection in Jet Engine Vibration Data." Key Engineering Materials 347 (September 2007): 305–10. http://dx.doi.org/10.4028/www.scientific.net/kem.347.305.
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A novelty detection approach to condition monitoring of aerospace gas-turbine engines is presented, providing a consistent framework for on- and off-line analysis, each with differing typical implementation constraints. On-line techniques are introduced for observing abnormality in engine behaviour during aircraft flights, and are shown to provide early warning of engine events in real-time. Off-line techniques within the same analysis framework are shown to allow the tracking of single engines and fleets of engines from ground-based monitoring stations on a flight-by-flight basis. Results are validated by comparison to conventional techniques, in application to aerospace engines and other industrial high-integrity systems.
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Bhasha, Sanjeev Gautam, Parul Malik, and Purnima Jain. "Ceramic Composites for Aerospace Applications." Diffusion Foundations 23 (August 2019): 31–39. http://dx.doi.org/10.4028/www.scientific.net/df.23.31.
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Ceramic composites is playing crucial role to accomplish highly efficiently and cost effective equipment for aerospace industry. The instigation of ceramics into aircraft industry is a promising step towards virtuous future. Ceramics has a key role in innovation of highly competent material for space travel which is highly economical and environmentally sustainable. Advancement in making fuel efficient engines are necessity in present scenario due to the harmful emissions releases in the environment by burning of fuel to power up engine. The high temperature application of composites makes it very attractive for aerospace applications. This light weight material has potential to thrust spacecraft upto ten times quicker with the identical fuel consumption, therefore significantly depreciating size of vehicle and increasing travel distance. The implementation of ceramics into jet engines and turbines increase the efficiency of engine due to its lighter weight and better thermal capabilities. A jet engine employing ceramic composites has manifest 15% more fuel saving when compared to the simple nickel based alloys. Hence, ceramic composites can replace nickel based alloys which has been a promising candidate for the engines of commercial aircrafts. Some disadvantages has been also discussed that is brittle failure and limited thermal and shock resistance.
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Skliros, Christos. "A CASE STUDY OF VIBRATION FAULT DIAGNOSIS APPLIED AT ROLLS-ROYCE T-56 TURBOPROP ENGINE." Aviation 23, no. 3 (January 17, 2020): 78–82. http://dx.doi.org/10.3846/aviation.2019.11900.
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Gas turbine engines include a plethora of rotating modules, and each module consists of numerous components. A component’s mechanical fault can result in excessive engine vibrations. Identification of the root cause of a vibration fault is a significant challenge for both engine manufacturers and operators. This paper presents a case study of vibration fault detection and isolation applied at a Rolls-Royce T-56 turboprop engine. In this paper, the end-to-end fault diagnosis process from starting system faults to the isolation of the engine’s shaft that caused excessive vibrations is described. This work contributes to enhancing the understanding of turboprop engine behaviour under vibration conditions and highlights the merit of combing information from technical logs, maintenance manuals and engineering judgment in successful fault diagnosis.
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Gosala, Dheeraj B., Cody M. Allen, Aswin K. Ramesh, Gregory M. Shaver, James McCarthy, Dale Stretch, Edward Koeberlein, and Lisa Farrell. "Cylinder deactivation during dynamic diesel engine operation." International Journal of Engine Research 18, no. 10 (February 1, 2017): 991–1004. http://dx.doi.org/10.1177/1468087417694000.
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Cylinder deactivation can be implemented at low loads in diesel engines to improve efficiency and aftertreatment thermal management through reductions in pumping work and airflow, respectively. The rate of increase of torque/power during diesel engine transients is limited by the engine’s ability to increase the airflow quickly enough to allow sufficient fuel addition to meet the desired torque/power. The reduced airflow during cylinder deactivation needs to be managed properly so as to not slow the torque/power response. This paper demonstrates that it is possible to operate a diesel engine at low loads in cylinder deactivation without compromising its transient torque/power capabilities, a key finding in enabling the practical implementation of cylinder deactivation in diesel engines.
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Yu, Bing, Wenjun Shu, and Can Cao. "A Novel Modeling Method for Aircraft Engine Using Nonlinear Autoregressive Exogenous (NARX) Models Based on Wavelet Neural Networks." International Journal of Turbo & Jet-Engines 35, no. 2 (May 25, 2018): 161–69. http://dx.doi.org/10.1515/tjj-2017-0005.
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Abstract A novel modeling method for aircraft engine using nonlinear autoregressive exogenous (NARX) models based on wavelet neural networks is proposed. The identification principle and process based on wavelet neural networks are studied, and the modeling scheme based on NARX is proposed. Then, the time series data sets from three types of aircraft engines are utilized to build the corresponding NARX models, and these NARX models are validated by the simulation. The results show that all the best NARX models can capture the original aircraft engine’s dynamic characteristic well with the high accuracy. For every type of engine, the relative identification errors of its best NARX model and the component level model are no more than 3.5 % and most of them are within 1 %.
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Sun, Huibin, and Zhiyong Chang. "An approach to configuration management in the aero-engine overhaul process." Aircraft Engineering and Aerospace Technology 90, no. 2 (March 5, 2018): 418–26. http://dx.doi.org/10.1108/aeat-11-2016-0198.
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Purpose The functionality and reliability of an overhauled aero-engine is determined by all configuration changes in the overhaul process. Identifying, recording, auditing, tracking and tracing of configuration modifications are significant and meaningful. Considering the barriers to these goals, this paper aims to put forward an approach to configuration management in the aero-engine overhaul process. Design/methodology/approach The overhaul configuration management model is proposed to describe an aero-engine’s configuration evolution trajectory in the overhaul process. The controlling and auditing procedures are put forward to control and audit parts’ return-to-zero statuses and overproof statuses. And some searching algorithms are also designed to enable tracking and tracing of the configuration status along the time coordinate, or get a snapshot of an aero-engine’s configuration at a certain time. The above model, procedures and algorithms have been implemented and adopted to fulfill the configuration management requirements in the aero-engine overhaul process. Findings The approach is effective in identifying, recording, controlling, auditing, tracking and tracing configuration changes in the overhaul process. Practical implications The approach’s implementation and adoption present a practical example for aero-engines’ configuration management issue in the overhaul process. Originality/value The work proposes an original aero-engine configuration management solution for the overhaul process and enables a reliable and accurate configuration management mode.
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Rubino, L., R. I. Crane, J. S. Shrimpton, and C. Arcoumanis. "An electrostatic trap for control of ultrafine particle emissions from gasoline-engined vehicles." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 4 (April 1, 2005): 535–46. http://dx.doi.org/10.1243/095440705x6668.
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Health concerns over ultrafine (< 100 nm) particles in the urban atmosphere have focused attention on measurement and control of particle number as well as mass. Gasoline-engined as well as diesel-engined vehicles are likely to be within the scope of future particulate matter (PM) emission regulations. As a potential option for after-treatment of PM emissions from gasoline engines, the trapping performance of a catalysed wire-cylinder electrostatic trap has been investigated, first in a laboratory rig with simulated PM and then in the exhaust of a direct injection spark ignition engine. In the simulation experiments, the trap achieved capture efficiencies by total particle number exceeding 90 per cent at wire voltages of 7–10 kV, gas temperatures up to 400°C, and operating durations up to one hour, with no adverse effects from a catalyst coating on the collecting electrode. In the engine tests, at moderate speeds and loads, capture efficiency was 60–85 per cent in the homogeneous combustion mode and 50–60 per cent, of a much larger number of engine-out particles, in the stratified (overall-lean) mode. Gas residence time in the trap appeared to be a major factor in determining efficiency. The electrical power requirement and the effect on engine back-pressure were both minimal.
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Buraimah, I. J. "Using modern clustering techniques for parametric fault diagnostics of turbofan engines." Civil Aviation High Technologies 23, no. 6 (December 31, 2020): 20–27. http://dx.doi.org/10.26467/2079-0619-2020-23-6-20-27.
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The 21st century aviation and aerospace technologies have evolved and become more complex and technical. Turbofan jet engines as well as their cousins, the rocket engines (liquid/solid) have gone through several design upgrades and enhancements during the course of their design and exploitation. These technological upgrades have made engines very complex and expensive machines which need constant monitoring during their working phase. As the demand and use of such engines is growing steadily, both in the civilian and military sectors, it becomes necessary to monitor and predict the behavior of parametric data generated by these complex engines during their working phases. In this paper flight parameters such as Exhaust Gas Temperature (EGT), Engine Fan Speeds (N1 and N2), Fuel Flow (FF), Oil Temperature (OT), Oil Pressure (OP), Vibration and others where used to determine engine fault. All turbo fan engines go through several distinctly different working phases: Take-off phase, Cruise phase and Landing phase. Recording generated parametric data during these different phases leads to a massive amount of in-flight data and maintenance reports, which makes the task of designing and developing a fault diagnostic system highly challenging. It becomes imperative to use modern techniques in data analysis that can handle large volumes of generated data and provide clear visual results for determining the technical status of the engine under investigation/monitoring. These modern techniques should be able to give clear and objective assessment of the object under investigation. Cluster analysis methods based on Neural Networks such as c-means, k-means, self-organizing maps and DBSCAN algorithm have been used to build clusters. Differences in cluster groupings/patterns between healthy engine and engine with degraded performance are compared and used as the bases for defining faults. Fault diagnosis plays a crucial role in aircraft engine management. Timely and accurate detection of faults is the foundation on which maintenance turnaround times, operational costs and flight safety are based. The data used in this paper for analysis was obtained from flight data recorder during one flight cycle. The final decision on a fault is taken by an engineer.
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Tziourtzioumis, D., L. Demetriades, O. Zogou, and A. M. Stamatelos. "Experimental investigation of the effect of a B70 biodiesel blend on a common-rail passenger car diesel engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 223, no. 5 (May 1, 2009): 685–701. http://dx.doi.org/10.1243/09544070jauto1094.
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The results of engine bench tests of a 2.0l common-rail high-pressure injection passenger car diesel engine fuelled by B70 biodiesel blend are compared with the corresponding results of baseline tests with standard EN 590 diesel fuel. Engine performance and carbon monoxide (CO), total hydrocarbon (THC), and nitrogen oxide (NO x) emissions were measured. Also, indicative particulate sampling was made with a simplified undiluted exhaust sampler. The aim of this study was to understand better how the engine's electronic control unit (ECU) responds to the different fuel qualities. A series of characteristic operation points for engine testing is selected to serve this purpose better. Data acquisition of the engine ECU variables was made through INCA software. Also, additional data acquisition based on external sensors was carried out by means of Labview software. The results enhance understanding of the engine ECU behaviour with the B70 biodiesel blend. Also, they are compared with what is known from the related literature for the behaviour of common-rail diesel engines with biodiesel blends.
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Wilde, G. L. "A New Approach to the Design of the Large Turbofan Power Plant." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 209, no. 2 (April 1995): 85–104. http://dx.doi.org/10.1243/pime_proc_1995_209_277_02.
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The lower direct operating costs of the Big Twin subsonic transports encourage the building of ever larger turbofan engines installed on the wings. The steadily improving reliability of the turbofans and the good safety statistics of twin-engined aircraft over many years encourages this trend. Fuel economy is still the dominant factor in determining the design layout of turbofan engines. It requires the combination of the highest possible thermal efficiency of the gas generator core of the engine with optimum propulsion efficiency of the power plant as a whole in cruise flight, allowing for engine nacelle drag and nacelle to wing interference drag. High thermal efficiency and high propulsion efficiency together, lead to relatively small volume flow rate gas generators and high volume flow rate propulsion fans. The resulting geometrical mismatch between the compressors and turbines of the principal turbomachinery components within the engine, introduces losses that penalize the performance gains expected from theoretical considerations of thermodynamics cycle and component efficiencies alone. The paper presents two possible turbofan design layouts intended to overcome the limitation of current turbofan power plant designs. The aim is to design a power plant with the highest thrust per unit frontal area combined with the highest air miles per gallon in cruise flight.
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Gloeckner, Peter, and W. Sebald. "A New Method of Calculating the Attainable Life and Reliability in Aerospace Bearings." European Journal of Engineering Research and Science 5, no. 6 (June 30, 2020): 745–50. http://dx.doi.org/10.24018/ejers.2020.5.6.1977.
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The aviation industry made significant progress improving reliability, efficiency and performance throughout the last decades. Especially aircraft engines and helicopter transmission systems contributed significantly to these improvements. The kerosene consumption decreased by 70 % and the CO2 emissions due to air transport decreased by 30 % per passenger kilometer within the last 20 years. Simultaneously, the flight safety was increased with aircraft engine in-flight-shut-downs as low as 1 ppm and „unscheduled engine removals” as low as 4 ppm. Flight safety is equal to the reliability of the systems in service. Failure of these systems directly leads to exposure of human life. Among the most critical aviation systems are aircraft engines including the rolling element bearings which support the rotors. A serious damage to the aircraft engine main shaft bearings during flight requires shout-down of the engine to avoid a further damage escalation subsequently leading to engine fire. Today, it is a requirement for aircraft to operate with one engine shut down. However, each in-flight-engine-shut-down typically is connected with flight diversion or abort and immediate landing. Inflight-shut-downs translate into increased risk for passengers and crew and substantial on cost. Therefore, rolling element bearings for aircraft engines are developed – similar to other aircraft engine components – targeting a reliability of nearly 100 % over an operation time of more than 10 000 hours prior to overhaul. To achieve this requirement despite the extreme operating conditions such as high speed and temperatures occurring in gas turbines, special high-performance materials are used for the rolling bearing components which are partially integrated in surrounding engine parts like shafts and housings. These special conditions - deviating from conventional industrial rolling element bearing applications - are currently not sufficiently considered in the standardized method of calculating the bearing life per ISO 281. A new method of calculating the attainable life of rolling elements bearing in aerospace applications is presented. This method considers the special aerospace conditions and materials and thus enables a higher reliability of the theoretical analysis and life prediction.
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Liu, K., and T. Cui. "Combustor-inlet interactions in a low-order dynamic model of ramjet engines." Aeronautical Journal 124, no. 1282 (July 29, 2020): 2001–18. http://dx.doi.org/10.1017/aer.2020.64.
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ABSTRACTThe coexistence of multiple stable states is indicative of self-organising processes occurring in the course of the combustor-inlet interactions in a ramjet engine and give rise to the appearance of various nonlinear phenomena. This paper provides a dynamic model that can describe the multiple stable states and the corresponding nonlinear effects to further investigate the dynamic interactions between combustor and inlet in a ramjet engine. Our study shows the whole engine can display distinct dynamic behaviours ranging from irreversibility to hysteresis and to various mode transitions, depending on different physical parameters. With the model, we also illustrate the role of the instability of the normal shock wave in impacting the whole engine’s nonlinear dynamics. Additionally, we extend the previous studies of the classification of combustor-inlet interactions from a static framework to a dynamic framework, which helps to clarify the transient processes of the nonlinear interactions. This work offers a quantitative illustration of the combustor-inlet interactions in a ramjet engine by revealing its nonlinear dynamics and associated characteristics, therefore advancing our understanding of the nonlinear phenomena that exhibit in ramjet engines.
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Kobayashi, Takahisa, and Donald L. Simon. "Integration of On-Line and Off-Line Diagnostic Algorithms for Aircraft Engine Health Management." Journal of Engineering for Gas Turbines and Power 129, no. 4 (May 1, 2007): 986–93. http://dx.doi.org/10.1115/1.2747640.
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This paper investigates the integration of on-line and off-line diagnostic algorithms for aircraft gas turbine engines. The on-line diagnostic algorithm is designed for in-flight fault detection. It continuously monitors engine outputs for anomalous signatures induced by faults. The off-line diagnostic algorithm is designed to track engine health degradation over the lifetime of an engine. It estimates engine health degradation periodically over the course of the engine’s life. The estimate generated by the off-line algorithm is used to “update” the on-line algorithm. Through this integration, the on-line algorithm becomes aware of engine health degradation, and its effectiveness to detect faults can be maintained while the engine continues to degrade. The benefit of this integration is investigated in a simulation environment using a nonlinear engine model.
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Pismennyi, V. L. "Hyper Afterburner Jet Engines." Proceedings of Higher Educational Institutions. Маchine Building, no. 01 (718) (January 2020): 51–62. http://dx.doi.org/10.18698/0536-1044-2020-1-51-62.
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This paper introduces a thrust augmentation method for super- and hypersonic jet engines by means of applying water at the engine intake. This method expands the use of jet engines with subsonic combustion, allowing velocities up to Mach 8 and altitude up to 45 km. At velocities higher than 3–4 Mach, stagnation temperature of the air is getting higher than the critical temperature of water, which makes the existence of water at the gas turbine engine intake impossible. Water vapour as a working medium of a jet engine creates the so-called inner thermodynamic circle. This phenomenon defines the physics of the thrust augmentation method proposed. The author discusses three variants of hyper afterburner application: hyper afterburner turbojet, hyper afterburner ramjet, and hyper afterburner turbo ejecting engine. The presented basic specifications of the hyper afterburner engines qualitatively differ from those of their prototypes (engines without the hyper afterburner thrust augmentation function). The proposed thrust augmentation method of jet engines is of a special interest for the aerospace field, particularly, for creating air launch systems. It is shown that the application of hyper afterburner in turbo ejecting engines can increase velocity and altitude of the launch aircraft up to Mach 7 and 40 km respectively, thus opening new avenues in space exploration.
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Ma, He, Ziyang Li, Mohamad Tayarani, Guoxiang Lu, Hongming Xu, and Xin Yao. "Model-based computational intelligence multi-objective optimization for gasoline direct injection engine calibration." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 6 (June 4, 2018): 1391–402. http://dx.doi.org/10.1177/0954407018776743.
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For modern engines, the number of adjustable variables is increasing considerably. With an increase in the number of degrees of freedom and the consequent increase in the complexity of the calibration process, traditional design of experiments–based engine calibration methods are reaching their limits. As a result, an automated engine calibration approach is desired. In this paper, a model-based computational intelligence multi-objective optimization approach for gasoline direct injection engine calibration is developed, which can optimize the engine’s indicated specific fuel consumption, indicated specific particulate matter by mass, and indicated specific particulate matter by number simultaneously, by intelligently adjusting the engine actuators’ settings through Strength Pareto Evolutionary Algorithm 2. A mean-value model of gasoline direct injection engine is developed in the author’s earlier work and used to predict the performance of indicated specific fuel consumption, indicated specific particulate matter by mass, and indicated specific particulate matter by number with given value of intake valves opening timing, exhaust valves closing timing, spark timing, injection timing, and rail pressure. Then a co-simulation platform is established for the introduced intelligence engine calibration approach in the given engine operating condition. The co-simulation study and experimental validation results suggest that the developed intelligence calibration approach can find the optimal gasoline direct injection engine actuators’ settings with acceptable accuracy in much less time, compared to the traditional approach.
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Baig, M. F., and N. Sayeed. "Model-based reasoning for fault diagnosis of twin-spool turbofans." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, no. 2 (February 1, 1998): 109–16. http://dx.doi.org/10.1243/0954410981532171.
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A simplified rule-based expert system can be of great use to maintenance engineers involved in on-line health monitoring of aero-engines. The development of a rule base has been done on the following lines: 1 A design and off-design mathematical model of the turbofan has been developed. 2 Healthy and fault-implanted engines have been run at various off-design conditions to see the effect of faults on certain aero-thermodynamic performance parameters, with appropriate selection of independent parameter(s). 3 From these calculated values, fault matrices have been developed for sea-level static conditions taking the net thrust as an independent parameter. 4 From these fault matrices, rules have been developed which form the knowledge core of the expert shell. These rules have been developed for Garrett TFE 731-2, a moderate bypass and overall pressure ratio, generic twin-spool turbofan and so the package (off-design code plus expert system) can serve as a pedagogical tool for training of engineers in the aero-engine industry and academic institutions.
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Guzzomi, A. L., D. C. Hesterman, and B. J. Stone. "Variable inertia effects of an engine including piston friction and a crank or gudgeon pin offset." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 3 (March 1, 2008): 397–414. http://dx.doi.org/10.1243/09544070jauto590.
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In order to obtain greater accuracy in simulation, more sophisticated models are often required. When it comes to the torsional vibration of reciprocating mechanisms the effect of inertia variation is very important. It has been shown that the inclusion of this variation increases model accuracy for both single-cylinder and multi-cylinder engine torsional vibration predictions. Recent work by the present authors has revealed that piston-to-cylinder friction may modify an engine's ‘apparent’ inertia function. Kinematic analysis also shows that the piston side force and the dynamic piston-to-cylinder friction are interdependent. This has implications for engine vibration modelling. Most modern engines employ a gudgeon pin offset, and there is a growing interest in pursuing large crank offsets; hence, the effect of these on inertia variation is also of interest. This paper presents the derivation of the inertia function for a single engine mechanism, including both piston-to-cylinder friction and crank or gudgeon pin offset, and investigates the effect of each through predictions. The effect of crank offset on the variable inertia function is also verified by experiment.
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Lolis, P., P. Giannakakis, V. Sethi, A. J. B. Jackson, and P. Pilidis. "Evaluation of aero gas turbine preliminary weight estimation methods." Aeronautical Journal 118, no. 1204 (June 2014): 625–41. http://dx.doi.org/10.1017/s0001924000009404.
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AbstractThe estimation of gas turbine engine weight during the preliminary or conceptual design phase is a key part of a Techno-economic Environmental Risk Analysis (TERA). Several methods that are available in the public domain are analysed and compared, in order to establish the physics driving them and their suitability for the weight estimation of modern gas turbine engines. Among the tested methods, only WATE managed to achieve acceptable accuracy for engine optimisation studies. This work demonstrates that the age and restrictions of existing ‘whole engine based’ methods, along with their dependency on old engine databases make them unsuitable for future and novel aero engines. A hybrid weight modelling approach is proposed as a solution permitting the creation of simple ‘whole engine based’ methods that do not depend on the availability of existing engine data, which are also subject to uncertainties and incoherencies.
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Geiß, Ingmar, and Rudolf Voit-Nitschmann. "Sizing of fuel-based energy systems for electric aircraft." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 12 (August 4, 2017): 2295–304. http://dx.doi.org/10.1177/0954410017721254.
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Optimized electric motors are lighter and smaller than conventional piston engines. As a result, new airplane configurations are feasible as motors can be placed in unconventional positions. Through careful aircraft design higher aerodynamic efficiencies of airframe, propeller, and propeller integration can be achieved. The energy density of current batteries, however, still limits strongly the range of purely battery powered aircraft. But if the energy is stored in liquid fuel and converted by a generator into electric energy, then the advantages of electric propelled airplanes and conventional combustion engines can be combined. But which combustion engine is optimal for such a serial-hybrid electric aircraft? In this new propulsion chain, other boundary conditions apply to the combustion engine than in conventional aircraft designs. These boundary conditions interact with the characteristics of combustion engines. An example for an engine characteristic is that different kinds of piston engines exist. It can be observed that technologies, which result in lighter piston engines, are associated with lower efficiencies and vice versa. In this paper it will be shown through considerations on aircraft level, that the optimal combustion engine for an electric-hybrid airplane should be heavier and more efficient than the optimal combustion engine for a conventional aircraft.
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Goulos, I., J. Otter, T. Stankowski, D. Macmanus, N. Grech, and C. Sheaf. "Design optimisation of separate-jet exhausts for the next generation of civil aero-engines." Aeronautical Journal 122, no. 1256 (September 19, 2018): 1586–605. http://dx.doi.org/10.1017/aer.2018.95.
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ABSTRACTThe next generation of civil large aero-engines will employ greater bypass ratios compared with contemporary architectures. This results in higher exchange rates between exhaust performance and specific fuel consumption (SFC). Concurrently, the aerodynamic design of the exhaust is expected to play a key role in the success of future turbofans. This paper presents the development of a computational framework for the aerodynamic design of separate-jet exhaust systems for civil aero-engines. A mathematical approach is synthesised based on class-shape transformation (CST) functions for the parametric geometry definition of gas-turbine exhaust components such as annular ducts and nozzles. This geometry formulation is coupled with an automated viscous and compressible flow solution method and a cost-effective design space exploration (DSE) approach. The framework is deployed to optimise the performance of a separate-jet exhaust for very-high-bypass ratio (VHBR) turbofan engine. The optimisations carried out suggest the potential to increase the engine’s net propulsive force compared with a baseline architecture, through optimum exhaust re-design. The proposed method is able to identify and alleviate adverse flow-features that may deteriorate the aerodynamic behaviour of the exhaust system.
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Luo, Gang, Chi Ma, Wei Chen, Lulu Liu, and Zhenhua Zhao. "Transient Analysis and Safety Assessment of Turbofan Engine Structures during Bird Ingestion." International Journal of Aerospace Engineering 2020 (July 17, 2020): 1–17. http://dx.doi.org/10.1155/2020/7404587.
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The high bypass ratio turbofan engine’s load-carrying structure transient response during bird ingestion was analyzed in accordance with the engine bird ingestion certification regulations, the principles of structural safety assessment were represented, and the structural safety analysis and assessment method of Turbo-Fan engine during bird ingestion were proposed. A high bypass ratio turbofan engine’s FEM was established and verified the rationality when its’ operation. Large bird ingestion into an engine’s procedure was conducted, the dynamic responses of key components on engine’s load-carrying structures during the bird ingestion were discussed, and the safety assessment consequence was obtained. We draw a conclusion that the relevant analysis/simulation data could be submitted to engine certification administration as key documents, the structural safety analysis and assessment method of turbofan engine due to bird ingestion could be applied as analysis and prediction work in the engine bird ingestion certification.
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Wang, Yiwei, and Xianghua Huang. "Performance Seeking Control of Propfan Engines Based on Modified Cuckoo Search." International Journal of Turbo & Jet-Engines 37, no. 4 (November 18, 2020): 363–70. http://dx.doi.org/10.1515/tjj-2017-0034.
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AbstractPerformance seeking control benefits propfan engine by generating optimal performance in different flight status. It is based on engine model, control model and optimization model. The control scheme of propfan engine is different from those of turbofan engines, for the thrust of propfan engines is mainly produced by propfans. After analysing the control structure of propfan engines, a control scheme for the propfan engine is proposed. The control scheme works well in flight envelope and the simulation results show that the overshoot of power shaft rotation speed is less than 2 % and the settling time is less than 0.9s. Based on this, a control scheme in performance seeking mode is proposed. A Modified Cuckoo Search method, which modifies the search step size and abandonment rate, is applied in the control scheme in maximum thrust mode and minimum fuel flow mode. The control scheme in performance seeking mode can reduce 2 % fuel flow, compared with the control scheme in torque-compensation mode. Performance of the scheme is better than standard Cuckoo Search and Genetic Algorithm.
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Lee, K., C. Lee, and Y. Joo. "Optimization of the intake port shape for a five-valve gasoline engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, no. 6 (June 1, 2001): 739–46. http://dx.doi.org/10.1243/0954407011528310.
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For the development of a high efficiency gasoline engine, the optimization of the intake port shape for a five-valve engine has been studied. Intake multivalve cylinder heads were manufactured by using a three-dimensional computer-assisted design program, and steady state flow experiments and flow visualization experiments have been performed with these cylinder heads. The five-valve engines, which have larger valve opening areas, have larger intake flowrates and higher tumble ratios than the four-valve engines. The effects of intake port design parameters of a five-valve engine on the intake flowrate and tumble were studied, and the design guidelines for the five-valve engines were established.
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Katrašnik, Tomaž, Ferdinand Trenc, Vladimir Medica, and Stojan Markič. "An Analysis of Turbocharged Diesel Engine Dynamic Response Improvement by Electric Assisting Systems." Journal of Engineering for Gas Turbines and Power 127, no. 4 (July 23, 2004): 918–26. http://dx.doi.org/10.1115/1.1924533.
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It is well known that turbocharged diesel engines suffer from an inadequate response to sudden load increase, this being a consequence of the nature of the energy exchange between the engine and the turbocharger. The dynamic response of turbocharged diesel engines could be improved by electric assisting systems, either by direct energy supply with an integrated starter-generator-booster (ISG) mounted on the engine flywheel, or indirect energy supply with an electrically assisted turbocharger. A previously verified zero dimensional computer simulation method was used for the analysis of both types of electrical assistance. The credibility of the data presented is further assured by the experimentally determined characteristics of the electric motors used as input parameters of the simulation. The paper offers an analysis of the interaction between a turbocharged diesel engine operating under various load conditions and electric assisting systems, as well as the requirements for supporting electric motors suitable for the improvement of an engine’s dynamic response. It is evident that an electrically assisted turbocharger outperforms an integrated starter-generator-booster for vehicle application, however ISG is the preferred solution when instant power increase is demanded.
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Yin, F., and A. Gangoli Rao. "Performance analysis of an aero engine with inter-stage turbine burner." Aeronautical Journal 121, no. 1245 (September 4, 2017): 1605–26. http://dx.doi.org/10.1017/aer.2017.93.
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ABSTRACTThe historical trends of reduction in fuel consumption and emissions from aero engines have been mainly due to the improvement in the thermal efficiency, propulsive efficiency and combustion technology. The engine Overall Pressure Ratio (OPR) and Turbine Inlet Temperature (TIT) are being increased in the pursuit of increasing the engine thermal efficiency. However, this has an adverse effect on engine NOx emission. The current paper investigates a possible solution to overcome this problem for future generation Very High Bypass Ratio (VHBR)/Ultra High Bypass Ratio (UHBR) aero-engines in the form of an Inter-stage Turbine Burner (ITB). The ITB concept is investigated on a next generation baseline VHBR aero engine to evaluate its effect on the engine performance and emission characteristics for different ITB energy fractions. It is found that the ITB can reduce the bleed air required for cooling the HPT substantially (around 80%) and also reduce the NOx emission significantly (>30%) without penalising the engine specific fuel consumption.
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Thompson, G. J., C. M. Atkinson, N. N. Clark, T. W. Long, and E. Hanzevack. "Technical Note: Neural network modelling of the emissions and performance of a heavy-duty diesel engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 214, no. 2 (February 1, 2000): 111–26. http://dx.doi.org/10.1177/095440700021400201.
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Internal combustion engines are being required to comply with increasingly stringent government exhaust emissions regulations. Compression ignition (CI) piston engines will continue to be used in cost-sensitive fuel applications such as in heavy-duty buses and trucks, power generation, locomotives and off-highway applications, and will find application in hybrid electric vehicles. Close control of combustion in these engines will be essential to achieve ever-increasing efficiency improvements while meeting increasingly stringent emissions standards. The engines of the future will require significantly more complex control than existing map-based control strategies, having many more degrees of freedom than those of today. Neural network (NN)-based engine modelling offers the potential for a multidimensional, adaptive, learning control system that does not require knowledge of the governing equations for engine performance or the combustion kinetics of emissions formation that a conventional map-based engine model requires. The application of a neural network to model the output torque and exhaust emissions from a modern heavy-duty diesel engine (Navistar T444E) is shown to be able to predict the continuous torque and exhaust emissions from a heavy-duty diesel engine for the Federal heavy-duty engine transient test procedure (FTP) cycle and two random cycles to within 5 per cent of their measured values after only 100 min of transient dynamometer training. Applications of such a neural net model include emissions virtual sensing, on-board diagnostics (OBD) and engine control strategy optimization.
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Cheng, W., D. G. Wilson, and A. C. Pfahnl. "Analytical efficiency comparison between gas turbine and gas turbine hybrid engines for passenger cars." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, no. 2 (February 1, 1997): 113–19. http://dx.doi.org/10.1243/0954407971526272.
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The performance and emissions of two alternative types of gas turbine engine for a chosen family vehicle are compared. One engine is a regenerative 71 kW gas turbine; the other is a hybrid power plant composed of a 15 kW gas turbine and a 7 MJ flywheel. These engines would give generally similar vehicle performance to that produced by 71 kW spark ignition and compression ignition engines. (The turbine engines would be lighter and, with a free power turbine, would have a more favourable torque-speed curve (1), giving them some advantages.) Results predict that for long-distance trips the hybrid engine would have a considerably better fuel economy and would produce lower emissions than the piston engines, and that the ‘straight’ gas turbine would be even better. For shorter commuting trips the hybrid would be able to run entirely from energy acquired and stored from house electricity, and it could therefore be the preferred choice for automobiles used primarily for urban driving when environmental factors are taken into account. However, the degradation of remaining energy in flywheel batteries and thermal energy in the regenerator and other engine hot parts between use periods will result in more energy being used than for the straight gas turbine engine using normal liquid fuel. The higher initial cost and greater complexity of the hybrid engine will be additional disadvantages.
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Verhelst, S., S. Verstraeten, and R. Sierens. "A comprehensive overview of hydrogen engine design features." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 221, no. 8 (August 1, 2007): 911–20. http://dx.doi.org/10.1243/09544070jauto141.
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Realizing decreased CO2 emissions from the transport sector will be possible in the near future when substituting (part of) the currently used hydrocarbon-fuelled internal combustion engines (ICEs) with hydrogen-fuelled ICEs. Hydrogen-fuelled ICEs have advanced to such a stage that, from the engine point of view, there are no major obstacles to doing this. The present paper indicates the advantages of hydrogen as a fuel for spark ignition (SI) internal combustion engines. It also shows how the hydrogen engine has matured. An extensive overview is given of the literature on experimental studies of abnormal combustion phenomena, mixture formation techniques, and load control strategies for hydrogen-fuelled engines. The Transport Technology research group of the Department of Flow, Heat and Combustion Mechanics at Ghent University has been working on the development and optimization of hydrogen engines for 15 years. An overview of the most important experimental results is presented with special focus on the most recent findings. The article concludes with a list of engine design features of dedicated hydrogen SI engines.
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Thompson, B. D., and R. H. Badgley. "Application of an Advanced Hybrid Rotordynamics Model to the Complete Structure of a Marine Gas Turbine Engine." Journal of Engineering for Gas Turbines and Power 110, no. 4 (October 1, 1988): 578–84. http://dx.doi.org/10.1115/1.3240174.
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Extensive fleet experience with the LM2500 marine gas turbine engine has identified it as an engine that exhibits wear-accelerating vibration effects. The critical speeds and associated mode shapes were not well understood by U.S. Navy engineers. To help deal with vibration-related problems, an analytical model was developed to calculate engine rotordynamic and structural response. The procedure is a multilevel, multirotor hybrid extension of the classical Myklestad-Prohl method. Presented herein are some of the model’s predictions, and correlations with actual engine vibration measurements. The model predicted in excess of 20 different critical speeds in the engine’s operating range. Because of the engine’s structural flexibility, most of the critical speeds were engine casing and structural support resonances, driven by imbalance or misalignment in one or both of the engine rotors. Rotor-bending critical speeds were found to be strongly influenced by engine casing and support structure stiffness and mass. Using the model’s predicted mode shapes, new mounting locations for accelerometers could be selected to determine vibration severity at various frequencies better. This has given the U. S. Navy new insights into fleet vibration problems, and provides a useful tool for achieving reduced engine removals.
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Denning, R. M., and N. A. Mitchell. "Trends in Military Aircraft Propulsion." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 203, no. 1 (January 1989): 11–23. http://dx.doi.org/10.1243/pime_proc_1989_203_049_01.
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The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design. Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics. The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed. Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.
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Zheng, Hao, Fuwu Yan, Chihua Lu, Fengxiang Xu, Qiuyue Li, and Wei Tian. "Optimization design of the valve spring for abnormal noise control in a single-cylinder gasoline engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 2 (August 5, 2016): 204–13. http://dx.doi.org/10.1177/0954407016651180.
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To address the abnormal noise problem of single-cylinder gasoline engines in the idle condition, acoustic spectral and intensity analysis was carried out. Then the noises were identified as valve impact noises caused by the anomalous dynamic performance of the engine valve mechanism. To improve further the dynamic performance of the mechanism by optimization of the valve spring, a multi-body dynamic model of the valve mechanism was developed on the basis of the key performance and the structure parameters of the valve spring. By using the optimization strategy, the oscillation amplitude of the valve spring and the valve impact force can be reduced by about 62.5% and 27% respectively. Finally, optimized sample pieces were produced for acoustic verification tests. The obtained results showed that the engine’s overall working noise was reduced by about 2.0 dB(A), and the sound quality of the engine was determined using both objective measurements and subjective evaluation of the noise, vibration and harshness performance. It can be concluded that the valve impact noise can be reduced by optimization of the valve springs.
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Cheng, Li, Pavlos Dimitriou, William Wang, Jun Peng, and Abdel Aitouche. "A novel fuzzy logic variable geometry turbocharger and exhaust gas recirculation control scheme for optimizing the performance and emissions of a diesel engine." International Journal of Engine Research 21, no. 8 (October 31, 2018): 1298–313. http://dx.doi.org/10.1177/1468087418809261.
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Variable geometry turbocharger and exhaust gas recirculation valves are widely installed on diesel engines to allow optimized control of intake air mass flow and exhaust gas recirculation ratio. The positions of variable geometry turbocharger vanes and exhaust gas recirculation valve are predominantly regulated by dual-loop proportional–integral–derivative controllers to achieve predefined set-points of intake air pressure and exhaust gas recirculation mass flow. The set-points are determined by extensive mapping of the intake air pressure and exhaust gas recirculation mass flow against various engine speeds and loads concerning engine performance and emissions. However, due to the inherent nonlinearities of diesel engines and the strong interferences between variable geometry turbocharger and exhaust gas recirculation, an extensive map of gains for the P, I, and D terms of the proportional–integral–derivative controllers is required to achieve desired control performance. The present simulation study proposes a novel fuzzy logic control scheme to determine appropriate positions of variable geometry turbocharger vanes and exhaust gas recirculation valve in real-time. Once determined, the actual positions of the vanes and valve are regulated by two local proportional–integral–derivative controllers. The fuzzy logic control rules are derived based on an understanding of the interactions among the variable geometry turbocharger, exhaust gas recirculation, and diesel engine. The results obtained from an experimentally validated one-dimensional transient diesel engine model showed that the proposed fuzzy logic control scheme is capable of efficiently optimizing variable geometry turbocharger and exhaust gas recirculation positions under transient engine operating conditions in real-time. Compared to the baseline proportional–integral–derivative controllers approach, both engine’s efficiency and total turbo efficiency have been improved by the proposed fuzzy logic control scheme while NOx and soot emissions have been significantly reduced by 34% and 82%, respectively.
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Kenny, R. G. "Developments in Two-Stroke Cycle Engine Exhaust Emissions." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 206, no. 2 (April 1992): 93–106. http://dx.doi.org/10.1243/pime_proc_1992_206_165_02.
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This paper is concerned with the exhaust emissions from two-stroke cycle spark ignition engines and the means being investigated to reduce them. The simple two-stroke engine has inherently low levels of NOx emissions and high levels of hydrocarbon emissions. The reasons for these emissions characteristics are explained by reference to the open literature. The two-stroke engine is used in a wide range of applications including low-cost, low-output mopeds and high-performance motorcycles. More recently there has been a resurgence of interest in the two-stroke as an alternative to the four-stroke engine for automotive use. A number of the recently reported approaches to emissions control are reviewed, including the use of exhaust oxidation catalysts in simple low-cost engines and direct fuel injection on more costly, multi-cylinder engines.
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Andoga, Rudolf, Ladislav Főző, Jozef Judičák, Róbert Bréda, Stanislav Szabo, Róbert Rozenberg, and Milan Džunda. "Intelligent Situational Control of Small Turbojet Engines." International Journal of Aerospace Engineering 2018 (June 26, 2018): 1–16. http://dx.doi.org/10.1155/2018/8328792.
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Improvements in reliability, safety, and operational efficiency of aeroengines can be brought in a cost-effective way using advanced control concepts, thus requiring only software updates of their digital control systems. The article presents a comprehensive approach in modular control system design suitable for small gas turbine engines. The control system is based on the methodology of situational control; this means control of the engine under all operational situations including atypical ones, also integrating a diagnostic system, which is usually a separate module. The resulting concept has been evaluated in real-world laboratory conditions using a unique design of small turbojet engine iSTC-21v as well as a state-of-the-art small turbojet engine TJ-100. Our results show that such advanced control system can bring operational quality of an engine with old turbocompressor core iSTC-21v on par with state-of-the-art engines.
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Vankan, Wilhelmus J., Robert Maas, and Vincent Peyron. "Optimisation methodology for integrated equipment installation in new engine architecture nacelles." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 10 (December 21, 2019): 1706–20. http://dx.doi.org/10.1177/0954410019895883.
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The development of new higher efficiency turbofan aero engines requires several design enhancements that typically result in shorter and slimmer nacelles. Consequently these engines provide less space for the engine systems installation and for maintenance accessibility. In the Novel Integration of Powerplant System Equipment project, optimisation methodologies are being investigated and developed for the integrated installation of equipment into the restricted volume of new architecture engines’ nacelles. The underlying optimisation methodology is built on a graph based approach involving efficient routing algorithms. Besides the methodology, also the software implementation and its application to engine equipment installation design cases are presented in this paper.
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Nuszkowski, J., R. R. Tincher, and G. J. Thompson. "Evaluation of the NOx emissions from heavy-duty diesel engines with the addition of cetane improvers." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 223, no. 8 (August 1, 2009): 1049–60. http://dx.doi.org/10.1243/09544070jauto1114.
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The exhaust emissions from heavy-duty diesel engines (HDDEs) contribute to the degradation of ambient air quality; therefore, environmental agencies have created stringent emissions standards. Since the implementation of these standards, overall engine and fuel technology improvements have created a significant reduction in emissions. This study was completed in order to evaluate oxides of nitrogen (NO x) emissions from fuels with and without cetane-improving additives in recent and early production electronically controlled HDDEs. Five engines spanning the model years from 1991 to 2004 were tested using the Federal Test Procedure (FTP) dynamometer cycle with both petroleum-based diesel and B20 as the neat fuel. It was found that the additives had the most impact on reducing emissions at low engine powers, but the engine power range with an NO x benefit varied between engines. The cetane improvers were found only to reduce NO x below a cylinder gas density of 35kg/m3 at top dead centre. The lower compression ratio of the 1992 DDC S60 engines reduced the cylinder gas density and provided a larger optimal operating range for the cetane improvers. The cetane improvers reduced NO x at low engine powers and cylinder gas density for the B20 fuel but were less effective than for the neat petroleum fuels.
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Przybyła, Bartosz Stanisław, Radoslaw Przysowa, and Zbigniew Zapałowicz. "Implementation of a new inlet protection system into HEMS fleet." Aircraft Engineering and Aerospace Technology 92, no. 1 (January 6, 2020): 67–79. http://dx.doi.org/10.1108/aeat-11-2018-0289.
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Purpose EC-135P2+ helicopters operated by Polish Medical Air Rescue are highly exposed to environmental particles entering engines when performing helicopter emergency medical services. This paper aims to assess the effectiveness of inlet barrier filters installed to protect the engines, including their impact on maintenance. Design/methodology/approach The organisation adopted a comprehensive set of measures to predict and limit the impact of dust ingestion including visual inspections, health management and engine trend monitoring based on ground power checks’ (GPC) results. Three alternative particle separation solutions were considered. Finally, helicopter inlets were modified to allow the selected filter system to be installed, which reduced the number of particles ingested by the engine and prevented from premature overhauls. Findings The analyses carried out enabled not only the selection of the optimal filtration solution and its seamless implementation into the fleet but also confirmed its efficiency. After installing the filters, engines’ lifetime is extended from 500 to 4,500 flight hours while operating costs and the number of maintenance tasks was reduced significantly. Originality/value Lessons learned from operational experience show that a well-matched particle separation system can mitigate accelerated engine deterioration even if the platform is continuously exposed to environmental particles. The remaining useful life of engines can be predicted using performance models and data from GPC.
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Lin Tay, Kun, Wenbin Yu, Feiyang Zhao, and Wenming Yang. "From fundamental study to practical application of kerosene in compression ignition engines: An experimental and modeling review." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 2-3 (April 8, 2019): 303–33. http://dx.doi.org/10.1177/0954407019841218.
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The use of kerosene in direct injection compression ignition engines is fundamentally due to the introduction of the Single Fuel Concept. As conventional direct injection compression ignition diesel engines are made specifically to use diesel fuel, the usage of kerosene will affect engine emissions and performance due to differences between the fuel properties of kerosene and diesel. As a result, in order for kerosene to be properly and efficiently used in diesel engines, it is needful for the scientific community to know the properties of kerosene, its autoignition and combustion characteristics, as well as its emissions formation behavior under diesel engine operating conditions. Moreover, it is desirable to know the progress made in the development of suitable kerosene surrogates for engine applications as it is a crucial step toward the development of reliable chemical reaction mechanisms for numerical simulations. Therefore, in this work, a comprehensive review is carried out systematically to better understand the characteristics and behavior of kerosene under direct injection compression ignition engine relevant conditions. In this review work, the fuel properties of kerosene are summarized and discussed. In addition, fundamental autoignition studies of kerosene in shock tube, rapid compression machine, fuel ignition tester, ignition quality tester, constant volume combustion chamber, and engine are compiled and evaluated. Furthermore, experimental studies of kerosene spray and combustion in constant volume combustion chambers are examined. Also, the experimental investigations of kerosene combustion and emissions in direct injection compression ignition engines are discussed. Moreover, the development of kerosene surrogates, their chemical reaction mechanisms, and the modeling of kerosene combustion in direct injection compression ignition engines are summarized and talked about. Finally, recommendations are also given to help researchers focus on the areas which are still severely lacking.
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Ekinci, Sinan, and İlkay Yavrucuk. "Fast engine model for FMU-less small turbojet engines." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (August 5, 2019): 416–27. http://dx.doi.org/10.1177/0954410019867013.
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The focus of this paper is on small low-cost turbojet engines equipped with a gear-type fuel pump rather than a more traditional fuel metering unit. The incorporation of such type of fuel flow actuation devices introduce additional nonlinearities into the system and therefore make traditional modeling and system identification methods difficult to apply. In this paper, we propose a nonlinear fast engine model structure that can be used for various applications, including identification, modeling and simulation, and controller design of such sub-class turbojet engines. A high-fidelity turbojet engine model including its nonlinear gear-type fuel pump is developed, which is later used to generate the fast engine model. The parameters of the fast engine model are estimated using regression analysis. The identification procedure is also applied to real engine test data to verify the proposed approach.
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Mashayekh, Alireza, Timothy Jacobs, Mark Patterson, and John Etcheverry. "Prediction of air–fuel ratio control of a large-bore natural gas engine using computational fluid dynamic modeling of reed valve dynamics." International Journal of Engine Research 18, no. 9 (January 6, 2017): 900–908. http://dx.doi.org/10.1177/1468087416686224.
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Air–fuel ratio control of large-bore, two-stroke, natural gas engines, typically used in the oil and gas field, is critically important to maintain stable operation and emission compliance. Many two-stroke applications rely on reed valves to control air and gas induction, which can involve complicated gas flow behavior; standard gas dynamic relationships are typically insufficient to characterize such behavior. Computational fluid dynamic simulations offer the needed complexity, but even so the computational fluid dynamic models, as shown in this work, must also capture the dynamic behavior of the valves themselves. The current work reports on a computational fluid dynamics–based model representing this type of large-bore, two-stroke, natural gas engine using commercially available computational fluid dynamic software. The engine under study is an AJAX E-565 with rated power of 30 kW (40 HP), a bore of 216 mm (8½″), and a stroke of 254 mm (10″). The large engine geometry makes a relatively large solution domain, hence requiring an intense, time-consuming numerical investigation. This large-bore engine works at a rated speed of 525 RPM with a compression ratio of 6 to 1. Two approaches to modeling the reed valve are investigated: (1) a pressure difference–based user-defined function and (2) a fluid–structure interaction user-defined function. The pressure difference–based user-defined function captures reed valve behavior in a simple, binary fashion (i.e. valves are either open or closed based on the pressure difference between the intake pipe and the engine’s stuffing box). The fluid–structure interaction user-defined function, however, predicts the motion of the reed valve strips based on fluid and body motions; although a more complex solution, the fluid–structure interaction user-defined function accurately predicts the engine’s gas exchange process. In this article, the results of each method are presented and validated to show that the added complexity is necessary to properly predict (and thus eventually improve) the engine’s air–fuel ratio control.
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Lytviak, Oleksandr, Vasyl Loginov, Sergii Komar, and Yevhen Martseniuk. "Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer." Aerospace 8, no. 4 (April 17, 2021): 114. http://dx.doi.org/10.3390/aerospace8040114.
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Self-oscillations are one of the common problems in the complex automatic system, that can occur due to the features of the workflow and the design of the governor. The development of digital control systems has made it possible to damp self-oscillations by applying complex control laws. However, for hydromechanical systems, such way is unacceptable due to the design complexity and the governor cost. The objective of this work is to determine the parameters of the hydromechanical free turbine speed controller, ensuring the absence of self-oscillations during ground tests of the turboshaft engine with a hydraulic dynamometer. The TV3-117VM engine (Ukraine) with the NR-3VM regulator pump (Ukraine) was selected as the object of the study. However, self-oscillations can also occur in any modifications of the TV3-117 engine with any NR-3 regulator pump. The results of the research may be of interest to engineers and scientists who investigate the dynamics of automatic control systems for similar engines. The paper analyses the nonlinear features of the empirical characteristics of the FTSC leading to self-oscillations of the engine speed. The authors propose the mathematical model of the automatic control system dynamics, which takes into account all the features of the engine and regulator pump. It is shown that the load characteristics of the water brake and the helicopter main rotor can differ significantly. Research of the dynamic characteristics of the TV3-117VM engine was carried out. The analysis showed a good agreement between the calculation results and the field test results, and made it possible to determine the parameters of the controller, which lead to self-oscillations during test. Two cases are considered. The first case includes ground tests of the engine with a water brake; the second case—flight tests of the engine as part of the helicopter’s power plant. The data obtained make it possible to develop recommendations for adjusting the hydromechanical governor without testing it on the engine.
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Kowalewicz, A. "Methanol as a Fuel for Spark Ignition Engines: A Review and Analysis." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 207, no. 1 (January 1993): 43–52. http://dx.doi.org/10.1243/pime_proc_1993_207_158_02.
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A review and analysis of recent literature data on the use of methanol as an alternative fuel for internal combustion engines have been performed. The properties of methanol have been analysed from the point of view of its application to spark ignition (SI) and compression ignition (CI) engines. From this analysis it may be concluded that fewer modifications to the engine are expected when methanol is used in SI engines than in CI engines. Neat methanol is the most suitable, because all the positive properties of methanol as a fuel can be utilized. In the case of SI engines, only minor modifications of the fuel system and/or addition of ignition improver to the fuel are required. Use of methanol-gasoline blends of up to 15 per cent methanol (by volume) and diesel oil-methanol blends of up to 20 per cent methanol require only minor engine modifications. However, miscibility of methanol and conventional fuels is poor; in order to avoid fuel separation, mixtures of these fuels require fuel additives. Methanol engines burn cleaner and more efficiently, but have higher emissions of aldehydes, which increase with increasing mileage of the vehicle. In the presence of an oxidation catalyst unburned methanol can be converted to formaldehyde and simultaneously nitrous oxide to nitrogen dioxide. The advantage of engine fuelling with reformed methanol (CO + H2) is shown. The reasons for better efficiency, performance and less emissions (except of aldehydes) of methanol-fuelled SI engines in comparison with gasoline- and diesel oil-fuelled engines respectively have been analysed. Technical aspects of using methanol as an automotive fuel that have not yet been satisfactorily solved are pointed out. The feasibility of the widespread use of methanol as a transportation fuel for SI engines is discussed from technical, economic and ecological points of view. The need for further research and development work on problems related to methanol as a fuel for SI engines is also discussed.
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Alexiou, Alexios, Nikolaos Aretakis, Ioannis Kolias, and Konstantinos Mathioudakis. "Novel Aero-Engine Multi-Disciplinary Preliminary Design Optimization Framework Accounting for Dynamic System Operation and Aircraft Mission Performance." Aerospace 8, no. 2 (February 12, 2021): 49. http://dx.doi.org/10.3390/aerospace8020049.
Full textAbstract:
This paper presents a modular, flexible, extendable and fast-computational framework that implements a multidisciplinary, varying fidelity, multi-system approach for the conceptual and preliminary design of novel aero-engines. In its current status, the framework includes modules for multi-point steady-state engine design, aerodynamic design, engine geometry and weight, aircraft mission analysis, Nitrogen Oxide (NOx) emissions, control system design and integrated controller-engine transient-performance analysis. All the modules have been developed in the same software environment, ensuring consistent and transparent modeling while facilitating code maintainability, extendibility and integration at modeling and simulation levels. Any simulation workflow can be defined by appropriately combining the relevant modules. Different types of analysis can be specified such as sensitivity, design of experiment and optimization. Any combination of engine parameters can be selected as design variables, and multi-disciplinary requirements and constraints at different operating points in the flight envelope can be specified. The framework implementation is exemplified through the optimization of an ultra-high bypass ratio geared turbofan engine with a variable area fan nozzle, for which specific aircraft requirements and technology limits apply. Although the optimum design resulted in double-digit fuel-burn benefits compared to current technology engines, it did not meet engine-response requirements, highlighting the need to include transient-performance assessments as early as possible in the preliminary engine design phase.
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Messineo, Jérôme, and Toru Shimada. "Theoretical Investigation on Feedback Control of Hybrid Rocket Engines." Aerospace 6, no. 6 (June 3, 2019): 65. http://dx.doi.org/10.3390/aerospace6060065.
Full textAbstract:
Despite the fact that hybrid propulsion offers significant benefits, it still suffers from some limitations such as the natural oxidizer to fuel ratio shift which induces variations of the engines’ performances while operating. To overcome that issue, Japan Aerospace Exploration Agency (JAXA) has been studying an innovative concept for several years based on the combination of controlled axial and radial oxidizer injections, called altering-intensity swirling-oxidizer-flow-type engine. This type of motor is theoretically capable of managing both the thrust and the oxidizer to fuel ratio independently and instantaneously by using a feedback control loop. To be effective, such engines would require in-flight instantaneous and precise thrust and an oxidizer to fuel ratio measurements as well as an adapted feedback control law. The purpose of this study is to investigate the effect of measurement errors on the engine control and to propose a regulation law suitable for these motors. Error propagation analysis and regulation law are developed from fundamental equations of hybrid motors and applied in a case where resistor-based sensors are used for fuel regression rate measurement. This study proves the theoretical feasibility of hybrid engines feedback control while providing some methods to design the engine and regression rate sensors depending on the mission requirements.
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Simons, Emerald, and Valentin Soloiu. "Reduction of Aircraft Gas Turbine Noise with New Synthetic Fuels and Sound Insulation Materials." Transportation Research Record: Journal of the Transportation Research Board 2603, no. 1 (January 2017): 50–64. http://dx.doi.org/10.3141/2603-06.
Full textAbstract:
The need to reduce the sound and vibration characteristics in the aerospace industry is continuously increasing because of the need to meet FAA regulations, to reduce noise pollution, and to improve customer satisfaction. To improve customer satisfaction, aircraft and engine manufacturers must work to control sound and vibration levels so that passengers do not experience discomfort during a flight. Sound and vibration characteristics of a fixed-wing aircraft with jet engines are composed of complex-frequency contents that challenge engineers in the development of quiet engine designs, aerodynamic bodies, and advanced sound- and vibration-attenuating materials. One of the noisiest parts of an aircraft, the gas turbine, was analyzed in this research. In Part 1 of this project, the use of alternative fuels in a gas turbine engine was investigated to determine whether those fuels have negative effects on sound and vibration levels. Three types of fuels were used: Jet A as the reference fuel, natural gas–derived S-8, and coal-derived isoparaffinic kerosene (IPK). The alternative fuels, S-8 and IPK, are Fischer–Tropsch process fuels. Overall sound and vibration characteristics of the alternative fuels presented a similar pattern across the frequency spectrum to those of the reference fuel, with the alternative fuels being slightly quieter. In Part 2, the sound path was treated by introducing sound-absorbing materials and investigating their acoustic performance. A melamine-based foam and soy-based foam were used in this research. Melamine is very lightweight, has excellent thermal endurance, and is hydrophobic. The soy-based foam was selected for its potential application in the aerospace industry to work toward a greener aircraft, in an effort to promote environmental sustainability. The soy-based material reduced the sound level by more than 20 dB(A) and presented better performance than the melamine at high frequencies.