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Żywica, Grzegorz, Tomasz Kaczmarczyk, Eugeniusz Ihnatowicz, Paweł Bagiński, and Artur Andrearczyk. "Design and Manufacturing of Micro-Turbomachinery Components with Application of Heat Resistant Plastics." Mechanics and Mechanical Engineering 22, no. 2 (2020): 649–60. http://dx.doi.org/10.2478/mme-2018-0051.
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AbstractThe article discusses issues associated with the use of modern plastics for the construction of high-speed fluid-flow machines. Currently available plastics exhibit high chemical resistance as well as dimensional and shape stability across a wide temperature range. This allows them to be used for manufacturing components of micro turbomachinery, thereby reducing production time and costs. This article discusses the criteria for the selection of plastics suitable for a particular machine, namely micro turbogenerator operating in the organic Rankine cycle (ORC). In addition to the initial selection of materials based on their chemical and physical properties, strength calculations of selected turbogenerator subassemblies were carried out. The obtained results confirmed that some plastics can replace traditional materials used in the manufacture of ORC turbogenerators. This concerns, in particular, the components of the microturbine blade system. After the manufacture of a trial series of such components, it became apparent that, with appropriately chosen plastics, it is possible to shorten the machining time and reduce production costs, all while maintaining the required dimensional tolerances. The results obtained so far prove that it is possible to use plastics to produce components of modern turbomachines, for instance, parts of high-speed microturbines that have to withstand high operating temperatures.
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Jadhav, Mohananand, Anindya Chakravarty, and M. D. Atrey. "Turbomachinery selection: Generating the selection charts and extending their use beyond the conventional for cryogenic plants." Indian Journal of Cryogenics 44, no. 1 (2019): 23. http://dx.doi.org/10.5958/2349-2120.2019.00003.7.
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Kupferschmied, Peter, Pascal Ko¨ppel, Christian Roduner, and Georg Gyarmathy. "On the Development and Application of the Fast-Response Aerodynamic Probe System in Turbomachines—Part 1: The Measurement System." Journal of Turbomachinery 122, no. 3 (1999): 505–16. http://dx.doi.org/10.1115/1.1303702.
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This contribution gives an overview of the current state, performance, and limitations of the fast-response aerodynamic probe measurement system developed at the Turbomachinery Lab of the ETH Zurich. In particular, the following topics are addressed: • Probe technology: Miniature probes with tip diameter ranging from 0.84 to 1.80 mm (one-sensor and three-sensor probes, respectively) have been developed. New technologies derived from microelectronics and micromechanics have been used to achieve an adequate packaging of the microsensor chips used. Both the sensor packaging and the sensor calibration (time-independent and time-dependent) are crucial issues for the DC accuracy of any measurement. • Aerodynamic probe calibration: The methods used for the sensor calibration and the aerodynamic probe calibration, the pertinent automated test facilities, and the processing of the output data are briefly presented. Since these miniature probes are also capable of measuring the mean flow temperature, aspects related to the effective recovery factor and the self-heating of the probe tip are treated and some recommendations related to sensor selection are given. • Measurement system and data evaluation: The early measurement chain described in Gossweiler et al. (1995) has evolved into the fast-response aerodynamic probe system. This automatic system incorporates dedicated measurement concepts for a higher accuracy and a more efficient operation in terms of time and failures. An overview of the data evaluation process is given. The fast-response aerodynamic probe system has been tested in real-sized turbomachines under industrial conditions within the temperature limits of 140°C imposed by the sensor technology (axial-flow turbofan compressor, axial-flow turbine, centrifugal compressor). These applications confirmed the potential of the system and encouraged its further development. Now, the system is routinely used in the facilities of the Turbomachinery Lab and in occasional measurement campaigns in other laboratories. Part 2 of this contribution (Roduner et al.) will focus on the application of the fast-response aerodynamic probe system in a transonic centrifugal compressor of the ETH Turbomachinery Laboratory, while Part 3 (Ko¨ppel et al.) treats more sophisticated data analysis methods. [S0889-504X(00)01003-5]
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Huntington, R. A. "Evaluation of Polytropic Calculation Methods for Turbomachinery Performance." Journal of Engineering for Gas Turbines and Power 107, no. 4 (1985): 872–76. http://dx.doi.org/10.1115/1.3239827.
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Performance calculations for centrifugal compressors have been based on polytropic analysis for many years. The basic polytropic equation, in which head is found from gas pressure, temperature, and compressibility factor at the end points of compression, is applied by virtually all engineers involved with turbomachinery design, selection, or operation. The problems and errors associated with this simple calculation method when applied to nonideal gases have long been recognized. Schultz [1] proposed a correction factor to the head equation to compensate for the errors. This “polytropic head factor” correction is required by the ASME Power Test Code 10 [2] for the evaluation of compressor performance. Recently, the accuracy of even the corrected head equation has been questioned for the compression of gases to high pressures and an alternative calculation method has been proposed by Mallen and Saville [3]. Although differences were found between their method and the Schultz method of up to three percent, they did not show which method was more accurate. This paper evaluates the accuracy of these previous calculation methods and shows that both have errors for some compression calculations. In addition, a new polytropic calculation method is described and is shown to be substantially more accurate than the methods of both [1] and [3], thus allowing more precise evaluations of compressor performance.
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Carolus, Thomas H., and Christoph Moisel. "Bidirectional air turbines for oscillating water column systems: Fast selection applying turbomachinery scaling laws." International Journal of Marine Energy 18 (June 2017): 65–77. http://dx.doi.org/10.1016/j.ijome.2017.03.006.
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Klocke, F., T. Bergs, M. Busch, L. Rohde, M. Witty, and G. F. Cabral. "Integrated Approach for a Knowledge-Based Process Layout for Simultaneous 5-Axis Milling of Advanced Materials." Advances in Tribology 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/742360.
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Advanced materials, like nickel-based alloys, gain importance in turbomachinery manufacturing, where creating complex surfaces constitute a major challenge. However, milling strategies that provide high material removal rates at acceptable tooling costs demand optimized tool geometry and process parameter selection. In this paper, a description of circular milling is given, focusing on resulting engagement conditions. Regarding this, a test bench was designed to investigate the chip formation process in an analogy milling process. Furthermore, the methodology for the approach in the analogy process was developed. Results of a first test run in Inconel 718 verify the presented approach.
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Karalis, A. J., E. J. Sosnowicz, and Z. S. Stys. "Air Storage Requirements for a 220 MWe CAES Plant as a Function of Turbomachinery Selection and Operation." IEEE Power Engineering Review PER-5, no. 4 (1985): 34–35. http://dx.doi.org/10.1109/mper.1985.5528812.
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Karalis, A., E. Sosnowicz, and Z. Stys. "Air Storage Requirements for a 220 Mwe CAES Plant as a Function of Turbomachinery Selection and Operation." IEEE Transactions on Power Apparatus and Systems PAS-104, no. 4 (1985): 803–8. http://dx.doi.org/10.1109/tpas.1985.319077.
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Franken, Arnoud R. C., and Paul C. Ivey. "Enhancing Flow Field Measurements Through Adaptive Multidimensional Data Sampling." Journal of Engineering for Gas Turbines and Power 128, no. 3 (2005): 518–24. http://dx.doi.org/10.1115/1.2135822.
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A way to gain insight into the flow field conditions in turbomachinery is by carrying out a series of point measurements in a cross section of the flow, for example, with a miniature multihole pressure probe. A problem commonly encountered in situations like these is the selection of a suitable measurement grid layout and density for obtaining all essential information in a cost-effective and timely manner. In order to achieve the latter, a novel adaptive multidimensional data sampling technique has been developed at Cranfield University. This paper describes the underlying principles of this technique, the algorithms utilized, and the results obtained during its successful application to data sets of two different flow fields in a high-speed research compressor.
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Korakianitis, T. "Prescribed-Curvature-Distribution Airfoils for the Preliminary Geometric Design of Axial-Turbomachinery Cascades." Journal of Turbomachinery 115, no. 2 (1993): 325–33. http://dx.doi.org/10.1115/1.2929238.
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Blade surfaces with continuous curvature and continuous slope of curvature minimize the possibility of flow separation, lead to improved blade designs, and reduce the direct and inverse blade-design iterations for the selection of isolated airfoils and gas-turbine-blade cascades. A method for generating two-dimensional blade shapes is presented. The geometry near the trailing edge is specified by an analytic polynomial, the main portion of the blade surface is mapped using as input a prescribed surface-curvature distribution, and the leading edge is specified as a thickness distribution added to a construction line. This procedure is similar for the suction and pressure surfaces, and by specification it constructs continuous slope-of-curvature surfaces that result in smooth surface-Mach-number and surface-pressure distributions. The method can be used to generate subsonic or supersonic airfoils for compressors and turbines, or isolated airfoils. The resulting geometric shapes can be used as inputs to various blade-design sequences. It is shown that, with other cascade-design parameters being equal, increasing the stagger angle of turbine blades results in more front-loaded and thinner blades, and that there is an optimum stagger angle resulting in minimum wake thickness. The subsonic axial-turbine blade rows included for discussion in this paper have been designed by iterative modifications of the blade geometry to obtain a desirable velocity distribution. The blade-design method can be used to improve the aerodynamic and heat transfer performance of turbine cascades, and it can result in high-performance airfoils, even if using the direct method exclusively, in very few iterations.
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Paricharak, Hrushikesh, and S. K. Tiwari. "Structural and modal analysis of gas turbine blade using ansys." IOP Conference Series: Materials Science and Engineering 1259, no. 1 (2022): 012016. http://dx.doi.org/10.1088/1757-899x/1259/1/012016.
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Abstract Gas turbine technology has advanced significantly during the last twenty years. The advancement in materials technology, new coatings, and novel cooling techniques are driving the expansion. Material selection is critical since turbomachinery design is complicated, and material performance is directly connected to efficiency. The materials should be able to withstand high vibrations, high temperature, and pressure. In this work, the maximum stress and the deformation induced due to pressure were determined to study the vibrational response, mode shapes, and natural frequencies. Four different materials have been considered, namely Inconel 617, Titanium alloy, Rhenium alloy, and Nimonic 80A. A suitable material for a gas turbine blade was suggested after analyzing these materials. The 3D CAD model is modeled in CATIA V5 and analysis is carried out using FEM-based software ANSYS
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Korakianitis, T. "Hierarchical Development of Three Direct-Design Methods for Two-Dimensional Axial-Turbomachinery Cascades." Journal of Turbomachinery 115, no. 2 (1993): 314–24. http://dx.doi.org/10.1115/1.2929237.
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The direct and inverse blade-design iterations for the selection of isolated airfoils and gas turbine blade cascades are enormously reduced if the initial blade shape has performance characteristics near the desirable ones. This paper presents the hierarchical development of three direct blade-design methods of increasing utility for generating two-dimensional blade shapes. The methods can be used to generate inputs to the direct- or inverse-blade-design sequences for subsonic or supersonic airfoils for compressors and turbines, or isolated airfoils. The examples included for illustration are typical modern turbine cascades, and they have been designed by the direct method exclusively. The first method specifies the airfoil shapes with analytical polynomials. It shows that continuous curvature and continuous slope of curvature are necessary conditions to minimize the possibility of flow separation, and to lead to improved blade designs. The second method specifies the airfoil shapes with parametric fourth-order polynomials, which result in continuous-slope-of-curvature airfoils, with smooth Mach number and pressure distributions. This method is time consuming. The third method specifies the airfoil shapes by using a mixture of analytical polynomials and mapping the airfoil surfaces from a desirable curvature distribution. The third method provides blade surfaces with desirable performance in very few direct-design iterations. In all methods the geometry near the leading edge is specified by a thickness distribution added to a construction line, which eliminates the leading edge overspeed and laminar-separation regions. The blade-design methods presented in this paper can be used to improve the aerodynamic and heat transfer performance of turbomachinery cascades, and they can result in high-performance airfoils in very few iterations.
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Kozanecki, Zbigniew, Eliza Tkacz, Jakub Łagodziński, and Kacper Miazga. "Theoretical and Experimental Investigations of Oil-Free Bearings and their Application in Diagnostics of High-Speed Turbomachinery." Key Engineering Materials 588 (October 2013): 302–9. http://dx.doi.org/10.4028/www.scientific.net/kem.588.302.
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In order to reduce the risk of failures, the optimal design selection from the viewpoint of machine reliability must be conducted. Therefore, one should analyze thoroughly the dynamics of the rotor-bearing-casing system in the whole operating range of the machine. The rotating system presented in the paper is supported in non-conventional bearings. The actual study consists in the investigation of new coating materials in the bearing design and the improvement in rotating system dynamics to increase the total efficiency, maintain the cleanness of the working medium and ensure operation of bearings in wide temperature ranges. Despite many advantages, air-foil bearings meet problems of friction and wear in critical moments of their operation, furthermore their complete theoretical model is difficult to establish. Different modeling theories of such bearing dynamic characteristics are shortly described. The current tendency in numerical and experimental methods for diagnostics of rotor support systems of low power rotating machinery is outlined.
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Iliev, R., and Ts Tsalov. "Investigation of the efficiency of VAWTs at different wind speeds." IOP Conference Series: Earth and Environmental Science 1128, no. 1 (2023): 012011. http://dx.doi.org/10.1088/1755-1315/1128/1/012011.
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Abstract This paper presents results from an experimental and numerical study of different lift-based and drag-based vertical axis wind turbines (VAWTs). One of the main disadvantages of vertical axis wind turbines is the low efficiency and inability to self-starting at low wind speeds. The task of the study is to determine an efficient geometry of the turbine runner, which can generate higher power at the lowest wind speeds. A comparison has been made of the cut-in speed, rated speed, efficiency, and the self-starting capabilities. This work proposes an aerodynamic scheme for wind turbine runners, which can operate relatively more efficiently at low and variable winds. The presented results favour the selection of a wind turbine for operation in conditions of weak and variable wind. The experiments were conducted in the Laboratory of Hydro Power and Hydraulic Turbomachinery (HEHT Lab) at the Technical University of Sofia.
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Chu, V. Ch, M. Basati Panah, A. I. Suhanov та ін. "Мaterial Selection for Additive Manufacturing of the Shrouded Impeller of a High-Speed Centrifugal Compressor". Safety and Reliability of Power Industry 17, № 4 (2025): 272–79. https://doi.org/10.24223/1999-5555-2024-17-4-272-279.
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The traditional manufacturing process for shrouded impellers in centrifugal compressors is characterized as a multi-stage process, which involves attaching blades to the impeller and welding a cover disk to the blades. Despite the extensive experience gained with traditional manufacturing methods, including laser welding, transitioning to additive manufacturing technology offers significant advantages: it enables the production of a shrouded impeller as a single, seamless part with no joints, thereby reducing the likelihood of defects. This article examines the stress and deformation behavior of a shrouded impeller in a centrifugal compressor operating at high rotational speeds (60400 rpm). A three-dimensional model was created, and a strength analysis was conducted to evaluate the structural integrity of the impeller. The calculations were performed using the ANSYS Workbench 2019 software. The results identified the locations of maximum stress concentration, which occur at 30 – 40% of the main blade length and near the leading edges of the splitters. In these regions of stress concentration, the ductility of the impeller material was considered. The primary mechanical properties of the additive materials used for the impeller — stainless steel grade 316, aluminum alloy AlSi10Mg, titanium alloy Ti-6Al-4V, and martensitic steel 17-4PH — were specified. The analysis showed that the titanium alloy Ti-6Al-4V best satisfies both the strength and technological requirements.The conducted analysis facilitated the selection of a suitable material for the rotating components of high-speed turbomachinery.
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Ni, Ming, Zuojun Wei, Weimin Deng, Haibo Tao, Guangming Ren, and Xiaohua Gan. "Enhancing Multi-Hole Pressure Probe Data Processing in Turbine Cascade Experiments Using Structural Risk Minimization Principle." Aerospace 11, no. 12 (2024): 973. http://dx.doi.org/10.3390/aerospace11120973.
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Multi-hole pressure probes are crucial for turbomachinery flow measurements, yet conventional data processing methods often lack generalization for complex flows. This study introduces an innovative approach by integrating machine learning techniques with the structural risk minimization (SRM) principle, significantly enhancing the generalization capability of regression models. A comprehensive framework has been developed, combining SRM-based machine learning regression methods, such as ridge regression and kernel ridge regression, with hyperparameter optimization and S-fold cross-validation, to ensure robust model selection and accuracy. Validated using the McCormick function and applied to VKI-RG transonic turbine cascade measurements, the SRM-based methods demonstrated superior performance over traditional empirical risk minimization approaches, with lower error ratios and higher R2 values. Novel insights from SHAP analysis revealed subtle but significant differences in aerodynamic parameters, including a 0.63122° discrepancy in exit flow angle predictions, guiding the probe design and calibration strategies. This study presents a holistic workflow for improving multi-hole pressure probe measurements under high-subsonic conditions, representing a meaningful enhancement over traditional empirical methods and providing valuable references for practical applications.
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Siddiqui, Muhammad Ehtisham, Eydhah Almatrafi, Usman Saeed, and Aqeel Ahmad Taimoor. "Selection of Organic Fluid Based on Exergetic Performance of Subcritical Organic Rankine Cycle (ORC) for Warm Regions." Energies 16, no. 13 (2023): 5149. http://dx.doi.org/10.3390/en16135149.
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The organic Rankine cycle (ORC) exhibits considerable promise in efficiently utilizing low-to-medium-grade heat. Currently, there is a range of organic fluids available in the market, and selecting the appropriate one for a specific application involves considering factors such as the cycle’s thermodynamic performance, plant size, and compatibility with turbomachinery. The objective of our study is to examine the exergetic performance of the ORC with internal heat regeneration. We analyze 12 different organic fluids to evaluate their suitability based on parameters like exergy efficiency and heat exchange area requirements. Additionally, we investigate the need for internal heat regeneration by comparing the overall exergy performance with a simpler ORC configuration. To ensure broad applicability, we consider source temperatures ranging from 150 to 300 °C, which are relevant to industrial waste heat, geothermal sources, and solar energy. For each case, we calculate specific net power output and the UA value (heat exchanger conductance) to gain insights into selecting the appropriate organic fluid for specific source temperatures. Cyclohexane, benzene, isopropyl alcohol, and hexafluorobenzene show poor exergy efficiency due to their high boiling points. Pentane and cyclopentane provides the highest exergy efficiency of 62.2% at source temperature of 300 °C, whereas pentane is found to be the most suitable at source temperatures of 200 and 150 °C with exergy efficiency of 67.7% and 61.7%, respectively. At 200 °C source temperature, RE347mcc achieves 65.9% exergy efficiency. The choice of organic fluid for a given heat source is highly influenced by its critical properties. Moreover, the normal boiling temperature of the organic fluid significantly impacts exergy destruction during the condensation process within the cycle.
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Morabito, Alessandro, Jan Spriet, Elena Vagnoni, and Patrick Hendrick. "Underground Pumped Storage Hydropower Case Studies in Belgium: Perspectives and Challenges." Energies 13, no. 15 (2020): 4000. http://dx.doi.org/10.3390/en13154000.
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To avoid the geographical and topographical prerequisites of the conventional pumped hydro energy storage, the use of underground cavities as water reservoirs allows countries without steep topography, such as Belgium, to increase the potential of the energy storage capacity. Belgium abounds in disused mines and quarries convertible into water basins. In this article, two Belgian case studies are presented and discussed for their singularity. A slate quarry in Martelange is discussed in technical aspects proposing three operating scenarios. Moreover, a preliminary economic analysis of the underground pumped storage system and a greenhouse gas emission evaluation for the storage system’s lifetime are presented. The analysis for a 100 MW power plant estimates a total initial investment of over 12 million euros and two million of CO2 avoided over its lifetime. This article also proposes the use of the coal mine 500 m deep of Pérronnes-lez-Binche. The mine representation discussed here offers a high energy capacity, but the substantial head drop (from about 500 to 200 m) challenges the selection of the hydraulic turbomachinery. A 1D simulation computed in SIMSEN draws out the behaviour of the unusual hydraulic configuration of turbines in series.
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Khalak, A. "A Framework for Flutter Clearance of Aeroengine Blades." Journal of Engineering for Gas Turbines and Power 124, no. 4 (2002): 1003–10. http://dx.doi.org/10.1115/1.1492832.
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A framework for flutter operability assessment, based upon a new set of similarity parameters, has been developed. This set consists of four parameters which embrace both the performance characteristics in terms of corrected mass flow and corrected speed, and the flight condition in terms of inlet temperature and density (or, equivalently, inlet pressure). It is shown that a combined mass-damping parameter, g/ρ*, novel in the field of turbomachinery aeroelasticity, can summarize the individual effects of mechanical damping, g, and blade mass ratio, μ. A particular selection of four nondimensional parameters, including g/ρ* and a compressible reduced frequency parameter, K*, allows for a decoupling of corrected performance effects from purely aeroelastic effects, for a given machine and a specific modeshape. This view of flutter operability is applied to the analysis of full-scale engine data. The data exhibits the trend that increasing K* and increasing g/ρ* have stabilizing effects, which is consistent with previous work in flutter stability. We propose that these trends hold generally, and apply the trends towards constructing a flutter clearance methodology, a test procedure which satisfies the requirements for comprehensive flutter stability testing.
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Iliev, R. "Experimental analysis of cross-flow wind turbine with omni-directional multi-nozzle." IOP Conference Series: Earth and Environmental Science 1128, no. 1 (2023): 012012. http://dx.doi.org/10.1088/1755-1315/1128/1/012012.
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Abstract Using guiding devices is a method for increasing the efficiency of vertical wind turbines. The main problem of these devices is the hydraulic losses that occur from shading the turbine runner. Тhe geometry of the guide apparatus must ensure independence from the wind direction and allow free passage of the airflow through the blade cascade of the runner. This paper presents the results of a physical and numerical study of a cross-flow vertical wind turbine with an omni-directional guiding multi-nozzle. The task of the study is to determine the influence of the multi-nozzle on the efficiency of the turbine when the airflow changes its direction. The idea is inspired by the kinematics of the flow through the guide nozzle and runner of the cross-flow water turbine. The experiments were conducted in the Laboratory of Hydro Power and Hydraulic Turbomachinery (HEHT Lab) at the Technical University of Sofia. The obtained results are showing the influence of the multi-nozzle on the performance of the cross-flow wind turbine. They favour the selection of a suitable omni-directinoal guiding device for vertical axis wind turbines.
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He, Meng, Jianing Qi, Zhentai Zheng, Fen Shi, and Yunfeng Lei. "Numerical simulation of nickel-based alloys’ welding transient stress using various cooling techniques." High Temperature Materials and Processes 39, no. 1 (2020): 633–44. http://dx.doi.org/10.1515/htmp-2020-0067.
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AbstractNickel-based alloys play an important role in the field of high-temperature alloys, which are widely used in nuclear reactors, aerospace and components of turbomachinery. However, the high susceptibility of welding hot crack is a main shortcoming to nickel-based alloys. One of the methods that reduce hot cracking susceptibility is by adjusting element constitution of weld metal and another method is by reducing transient stress. This article used finite element method to study the effect of cooling source on transient stress of the nickel-based alloy weld joint. The selection of appropriate cooling technique can decrease the peak of the transient von Mises stress and make the tensile stress turn into compressive stress, which is beneficial to reduce hot cracking susceptibility. The peak of the transient von Mises stress decreases as the cooling intensity increases from 0 to 15,000 W/m2 K, but increases if the cooling intensity is ineffective. When the distance between cooling source and heat source reaches 35 mm, the weld can get larger region of compressive stress. The peak of the transient von Mises stress decreases with increasing radius of cooling source and reaches minimum value at 12 mm. Combined cooling is more effective in reducing the peak of this stress than the conventional single trailing cooling source.
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Manservigi, Lucrezia, Mauro Venturini, and Enzo Losi. "Optimal selection of pumps as turbines for maximizing electrical energy production." E3S Web of Conferences 238 (2021): 01005. http://dx.doi.org/10.1051/e3sconf/202123801005.
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A Pump as Turbine (PAT) is a renewable energy technology that can be a cost-effective and reliable alternative to hydraulic turbines in micro and small hydropower plants. In order to further favour PAT exploitation, a general procedure that allows the identification of the most suitable turbomachine to install is required. To this purpose, this paper develops a novel methodology aimed at selecting the best PAT that, among several alternatives, maximizes energy production. The methodology comprises two steps, which only require the knowledge of the best efficiency point of the considered pump and the hydraulic parameters of the site. The novel methodology is validated in this paper by calculating the electrical energy production of a simulated water distribution network coupled with several PATs, whose performance curves, both in direct and reverse modes, are taken from the literature. For the sake of generality, the considered turbomachines account for different geometrical characteristics, rotational speeds and operating ranges.
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de Zordo-Banliat, Maximilien, Xavier Merle, Gregory Dergham, and Paola Cinnella. "Estimates of turbulence modeling uncertainties in NACA65 cascade flow predictions by Bayesian model-scenario averaging." International Journal of Numerical Methods for Heat & Fluid Flow 32, no. 4 (2022): 1398–414. http://dx.doi.org/10.1108/hff-08-2021-0524.
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Purpose The Reynolds-averaged Navier–Stokes (RANS) equations represent the computational workhorse for engineering design, despite their numerous flaws. Improving and quantifying the uncertainties associated with RANS models is particularly critical in view of the analysis and optimization of complex turbomachinery flows. Design/methodology/approach First, an efficient strategy is introduced for calibrating turbulence model coefficients from high-fidelity data. The results are highly sensitive to the flow configuration (called a calibration scenario) used to inform the coefficients. Second, the bias introduced by the choice of a specific turbulence model is reduced by constructing a mixture model by means of Bayesian model-scenario averaging (BMSA). The BMSA model makes predictions of flows not included in the calibration scenarios as a probability-weighted average of a set of competing turbulence models, each supplemented with multiple sets of closure coefficients inferred from alternative calibration scenarios. Findings Different choices for the scenario probabilities are assessed for the prediction of the NACA65 V103 cascade at off-design conditions. In all cases, BMSA improves the solution accuracy with respect to the baseline turbulence models, and the estimated uncertainty intervals encompass reasonably well the reference data. The BMSA results were found to be little sensitive to the user-defined scenario-weighting criterion, both in terms of average prediction and of estimated confidence intervals. Originality/value A delicate step in the BMSA is the selection of suitable scenario-weighting criteria, i.e. suitable prior probability mass functions (PMFs) for the calibration scenarios. The role of such PMFs is to assign higher probability to calibration scenarios more likely to provide an accurate estimate of model coefficients for the new flow. In this paper, three mixture models are constructed, based on alternative choices of the scenario probabilities. The authors then compare the capabilities of three different criteria.
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Abdelrhman, Ahmed M., Lim Meng Hee, M. S. Leong, and Salah Al-Obaidi. "Condition Monitoring of Blade in Turbomachinery: A Review." Advances in Mechanical Engineering 6 (January 1, 2014): 210717. http://dx.doi.org/10.1155/2014/210717.
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Blade faults and blade failures are ranked among the most frequent causes of failures in turbomachinery. This paper provides a review on the condition monitoring techniques and the most suitable signal analysis methods to detect and diagnose the health condition of blades in turbomachinery. In this paper, blade faults are categorised into five types in accordance with their nature and characteristics, namely, blade rubbing, blade fatigue failure, blade deformations (twisting, creeping, corrosion, and erosion), blade fouling, and loose blade. Reviews on characteristics and the specific diagnostic methods to detect each type of blade faults are also presented. This paper also aims to provide a reference in selecting the most suitable approaches to monitor the health condition of blades in turbomachinery.
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Manservigi, Lucrezia, Mauro Venturini, Enzo Losi, and Giulia Anna Maria Castorino. "Optimal Selection and Operation of Pumps as Turbines for Maximizing Energy Recovery." Water 15, no. 23 (2023): 4123. http://dx.doi.org/10.3390/w15234123.
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A pump as turbine (PAT) can be a cost-effective and versatile solution to recover energy in several fields of application. However, its optimal exploitation requires a reliable and general methodology for selecting the optimal turbomachine. To this purpose, this paper presents and validates a comprehensive methodology that identifies the best turbomachine (i.e., the one that maximizes the recovered energy) by considering two hydraulic sites and forty-five PATs. In both sites, the methodology correctly identifies the best PAT, which allows for the recovery of up to 45% of the available hydraulic energy. To further investigate PAT potential, an additional layout of installation, which comprises two PATs installed in parallel, is also considered. The operation of both PATs is optimally scheduled to maximize energy recovery. As a result, the energy recovered by the best pair of PATs is almost 50% of the available hydraulic energy. An in-depth analysis about PAT operation (i.e., operating range, causes of wasted energy, timeframe of operation and PAT efficiency) reveals that the installation of two PATs is actually recommended in just one of the two considered sites.
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Murugan, Muthuvel, Michael Walock, Anindya Ghoshal, Robert Knapp, and Roger Caesley. "Embedded Temperature Sensor Evaluations for Turbomachinery Component Health Monitoring." Energies 14, no. 4 (2021): 852. http://dx.doi.org/10.3390/en14040852.
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Current rotorcraft gas turbine engines typically use titanium alloys and steel for the compressor section and single-crystal nickel superalloys for the hot-section turbine stator vanes and rotor blades. However, these material selections are rapidly changing due to increased requirements of power-density and efficiency. Future U.S. Army gas turbine engines will be using ceramic matrix composites for many high temperature engine components due to their low density and improved durability in high temperature environments. The gas turbine industry is also actively developing adaptive concept technologies for production and assembly of modular gas turbine engine components with integrated sensing. In order to actively monitor engine components for extended seamless operation and improved reliability, it is essential to have intelligent embedded sensing to monitor the health of critical components in engines. Under this U.S. Army Foreign Technology Assessment Support (FTAS) program funded research project, embedded fiber-optic temperature sensors from U.K.-based company, Epsilon Optics Ltd (Fordingbridge, UK)., were experimentally evaluated to measure temperature responses on typical turbomachinery component material coupons. The temperature responses from this foreign technology sensor were assessed using a thermomechanical fatigue tester with a built-in furnace to conduct thermal cycling durability experiments. The experimental results obtained from the durability performance of this embedded fiber Bragg sensor are reported in this paper. This sensor technology, upon maturation to higher TRL (technology readiness level), can greatly reduce the lifecycle cost of future U.S. Army gas turbine engines.
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Najjar, Yousef S. H. "Review of Aerothermally Induced Vibrations in Gas Turbine Engines." Energy & Environment 6, no. 2 (1995): 143–57. http://dx.doi.org/10.1177/0958305x9500600205.
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High or changing vibration amplitude patterns in turbomachines are signs of impending failure or a machines deterioration. If properly diagnosed, this information can help improve performance, reliability; reduce maintenance cost; and avoid serious outages. Vibrations could be caused by structural or aerodynamic excitations, in addition to combustion pulsations. Methods of decreasing vibrations are mentioned, where selection of proper materials plays an important role. These areas are reviewed briefly in this work.
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Terziev, Angel, Andrey Potashev, Elena Potasheva, et al. "Quasi-three-dimensional modeling as an effective tool for studying flows in turbomachines." IOP Conference Series: Earth and Environmental Science 1380, no. 1 (2024): 012020. http://dx.doi.org/10.1088/1755-1315/1380/1/012020.
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Abstract The development of software tools for calculating the flow of liquid and gas (the so-called computational fluid dynamics (CFD)) makes it possible to calculate the characteristics of the gas flow in areas with an increasingly complex configuration. In particular, the use of CFD tools is increasingly used to determine the flow parameters in the flow parts of turbomachines, such as fans, pumps, turbines, axial and centrifugal compressors. Despite the wide possibilities of these methods, they have the disadvantage of being very time consuming when creating a new flow path of turbomachines and selecting the blade geometry due to the need for numerous intermediate calculations. From this point of view, the use of faster programs based on approximate flow models in the flow parts of turbomachines is quite justified. It is their use that allows you to choose the geometry of the flow path and blades, as close as possible to the desired aerodynamic requirements. In this paper, using the example of calculating the gas flow through the flow path of a Ts4-70 centrifugal fan, the possibilities of such a model are demonstrated.
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Milewski, Jarosław, Arkadiusz Szczęśniak, Piotr Lis, et al. "Selecting Cycle and Design Parameters of a Super Critical CO2 Cycle for a 180 kW Biogas Engine." Energies 17, no. 12 (2024): 2982. http://dx.doi.org/10.3390/en17122982.
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The objective of this paper was to study the sCO2 cycle as a waste heat recovery system for a 180 kW biogas engine. The research methodology adopted was numerical simulations through two models built in different programs: Aspen HYSYS and GT Suite. The models were used to optimize the design and thermodynamic parameters of a CO2 cycle in terms of system power, system efficiency, expander, and compressor efficiency. Depending on the objective function, the sCO2 cycle could provide additional power ranging from 27.9 to 11.3 kW. Based on the calculation performed, “Recuperated cycle at maximum power” was selected for further investigation. The off-design analysis of the system revealed the optimum operating point. The authors designed the preliminary dimensions of the turbomachinery, i.e., the rotor dimension is 16 mm, which will rotate at 100,000 rpm.
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Picard, Benoit, Mathieu Picard, Jean-Sébastien Plante, and David Rancourt. "Optimum sub-megawatt electric-hybrid power source selection." Aircraft Engineering and Aerospace Technology 92, no. 5 (2020): 717–26. http://dx.doi.org/10.1108/aeat-06-2019-0119.
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Purpose The limited energy density of batteries generates the need for high-performance power sources for emerging eVTOL applications with radical operational improvement potential over traditional aircraft. This paper aims to evaluate on-design and off-design recuperated turbogenerator performances based on newly developed compression loaded ceramic turbines, the Inside-out Ceramic Turbine (ICT), in order to select the optimum engine configuration for sub-megawatt systems. Design/methodology/approach System-level thermal engine modeling is combined with electric generators and power electronics performance predictions to obtain the Pareto front between efficiency and power density for a variety of engine designs, both for recuperated and simple cycle turbines. Part load efficiency for those engines are evaluated, and the results are used for an engine selection based on a simplified eVTOL mission capability. Findings By operating with high turbine inlet temperature, variable output speed and adequately sized recuperator, a turbogenerator provides exceptional efficiency at both nominal power and part load operation for a turbomachine, while maintaining the high power density required for aircraft. In application with a high peak-to-cruise power ratio, such power source would provide eight times the range of battery-electric power pack and an 80% improvement over the state-of-the-art simple cycle turbogenerator. Practical implications The implementation of a recuperator would provide additional gains especially important for military and on-demand mobility applications, notably reducing the heat signature and noise of the system. The engine low-pressure ratio reduces its complexity and combined with the fuel savings, the system could significantly reduce operational cost. Originality/value Implementation of radically new ICT architecture provides the key element to make a sub-megawatt recuperated turbogenerator viable in terms of power density. The synergetic combination of a recuperator, high temperature turbine and variable speed electric generator provides drastic improvement over simple-cycle turbines, making such a system highly relevant as the power source for future eVTOL applications.
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Bobek, Szymon, Sławomir K. Tadeja, Łukasz Struski, et al. "Virtual Reality-Based Parallel Coordinates Plots Enhanced with Explainable AI and Data-Science Analytics for Decision-Making Processes." Applied Sciences 12, no. 1 (2021): 331. http://dx.doi.org/10.3390/app12010331.
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We present a refinement of the Immersive Parallel Coordinates Plots (IPCP) system for Virtual Reality (VR). The evolved system provides data-science analytics built around a well-known method for visualization of multidimensional datasets in VR. The data-science analytics enhancements consist of importance analysis and a number of clustering algorithms including a novel SuMC (Subspace Memory Clustering) solution. These analytical methods were applied to both the main visualizations and supporting cross-dimensional scatter plots. They automate part of the analytical work that in the previous version of IPCP had to be done by an expert. We test the refined system with two sample datasets that represent the optimum solutions of two different multi-objective optimization studies in turbomachinery. The first one describes 54 data items with 29 dimensions (DS1), and the second 166 data items with 39 dimensions (DS2). We include the details of these methods as well as the reasoning behind selecting some methods over others.
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Vásquez, Diego Penagos, Jonathan Graciano Uribe, Sebastián Vélez García, and Jorge Sierra del Rio. "Characteristic Curve Prediction of a Commercial Centrifugal Pump Operating as a Turbine Through Numerical Simulations." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, no. 1 (2021): 153–69. http://dx.doi.org/10.37934/arfmts.83.1.153169.
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In this work, we seek to predict the characteristic curve of a commercial centrifugal radial flow pump operating as a turbine, applying a novel methodology based on the state of the art. Initially, the characteristic curve in pump mode is validated through numerical simulations. The results obtained are approximate to the points awarded by the manufacturer, with an error of less than 7% at the best efficiency point. Subsequently, the characteristic curve is generated in turbine mode, obtaining an error of less than 10% respect to mathematical model. Then, velocity and pressure contours are evaluated to validate the fluid dynamic behavior. Finally, the site operating conditions for electricity generation are obtained. With this, it is proposing a methodology for the selection of these turbomachines, applying an economic technology for zones that do not have access to the electrical energy, since it was not found a method that is being applied for its correct election in the hydroelectric generation at low scale.
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Wang, Dingxi, Sen Zhang, and Xiuquan Huang. "Efficient analysis of unsteady flows within multi-stage turbomachines using the coupled time and passage spectral method." Journal of the Global Power and Propulsion Society 6 (August 18, 2022): 213–26. http://dx.doi.org/10.33737/jgpps/151117.
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A coupled time and passage spectral method has been proposed very recently for tracking blade wakes penetrating the immediate downstream blade row and reaching far downstream blade rows. To achieve an efficient numerical analysis, the number of time and space modes to be retained has to be limited, as the computational cost of such an analysis is at least proportional to the number of modes. In this study, time and space modes related to downstream propagation of blade wakes reaching beyond their immediate downstream blade row are ranked according to their amplitudes of flow quantities through a time domain harmonic balance analysis using a domain consisting of multiple blade passages for the third row to capture the wakes of the first row of a two-stage fan. Modes with significant amplitudes are identified and they are really sparse. This sparsity of significant modes provides the premise for an efficient analysis using the coupled time and passage spectral method. A guideline for <italic>a priori</italic> selection of time and space modes has been developed by analyzing the frequencies and nodal diameters of those significant modes. The guideline is subsequently verified through four different coupled time and passage spectral analyses with different levels of accuracy by including different time and space modes.
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Jahn, Ingo HJ. "Design approach for maximising contacting filament seal performance retention." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 5 (2014): 926–42. http://dx.doi.org/10.1177/0954406214541433.
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Good sealing is a key requirement for modern efficient turbomachinery such as steam and gas turbines. A class of seals that promise better performance, compared to conventional labyrinth seals, are contacting filament seals such as brush, leaf, or finger seal. When new, these filament seals offer better performance; however, if poorly designed they wear excessively, resulting in leakages higher than a comparable labyrinth seal. This paper outlines a design methodology for selecting ideal contacting filament seal properties for a given operating cycle or set of operating cycles. Following this approach ensures the seal performs well, the seal retains its performance, and performance is retained if the operating cycle is altered. In the approach, the seals are described by four generic properties (stiffness, blow-down, cross-coupling, and build clearance), which are then used for a performance evaluation based on a number of test cycles. Once the ideal seal properties for a given operating cycle have been identified, a seal to match these can be designed. The approach is evaluated with a generic gas turbine cycle and recommendations for ideal contacting filament seal properties for this cycle are made.
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Li, Pengfei, Yaping Hu, and Honghu Ji. "Numerical simulation of deformation hysteresis effect of the bristles of brush seals." Journal of Physics: Conference Series 2746, no. 1 (2024): 012019. http://dx.doi.org/10.1088/1742-6596/2746/1/012019.
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Abstract Because of their good sealing performance, brush seals are used widely in turbomachinery as alternatives to traditional labyrinth seals. However, obstructed by friction, the flexible bristles cannot recover fully after deformation, resulting in a hysteresis effect and decreased sealing performance. In the present study, a three-dimensional multi-row bristle model is established that considers the friction between the neighbouring bristles and back plate. Then the deformation and recovery of the bristles during the radial reciprocating offset of the rotor in the presence of a pressure difference are studied. To evaluate the hysteresis effect, analysis is directed at the unrecovered bristle deformation in the radial direction affected by bristle diameter, bristle lay angle, fence height and width of pressure relief chamber. The results show that the larger the bristle diameter and fence height, the weaker the hysteresis effect and the larger the bristle lay angle, the stronger the hysteresis effect. With increasing width of the pressure relief chamber, the hysteresis effect weakens and then strengthens, meaning that the pressure relief chamber has an optimal axial width that departure from enhances the hysteresis effect. The present results offer a reference for selecting the structural parameters of brush seals in engineering design.
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Lu, P. J., and S. K. Chen. "Evaluation of Acoustic Flutter Suppression for Cascade in Transonic Flow." Journal of Engineering for Gas Turbines and Power 124, no. 1 (2000): 209–19. http://dx.doi.org/10.1115/1.1365933.
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Flutter suppression via actively excited acoustic waves is a new idea proposed recently. The high flutter frequency (typically 50–500 Hz for a fan blade) and stringent space constraint make conventional mechanical type flutter suppression devices difficult to implement for turbomachines. Acoustic means arises as a new alternative which avoids the difficulties associated with the mechanical methods. The objective of this work is to evaluate numerically the transonic flutter suppression concept based on the application of sound waves to two-dimensional cascade configuration. This is performed using a high-resolution Euler code based on a dynamic mesh system. The concept has been tested to determine the effectiveness and limitations of this acoustic method. In a generic bending-torsion flutter study, trailing edge is found to be the optimal forcing location and the control gain phase is crucial for an effective suppression. The P&W fan rig cascade was used as the model to evaluate the acoustic flutter suppression technique. With an appropriate selection of the control logic the flutter margin can be enlarged. Analogous to what were concluded in the isolated airfoil study, for internal excitation, trailing-edge forcing was shown to be optimal since the trailing-edge receptivity still works as the dominant mechanism for generating the acoustically induced airloads.
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Guha, Abhijit, and Sayantan Sengupta. "A non-dimensional study of the flow through co-rotating discs and performance optimization of a Tesla disc turbine." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 8 (2017): 721–38. http://dx.doi.org/10.1177/0957650917715148.
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This article presents a systematic and comprehensive computational fluid dynamic study for co-rotating discs and, Tesla turbines, in which the full benefit of similitude and scaling is extracted by expressing the results and analyses in terms of carefully formulated non-dimensional numbers—five input parameters and three output parameters. The work formulates a systematic design methodology for the optimum selection of input parameters for the rotor of a Tesla disc turbine that would satisfy practical constraints and deliver high values of power and efficiency. Many subtle flow physics (e.g. the identification of dynamic similarity number, inlet tangential speed ratio and inlet flow angle as the three most important non-dimensional input parameters, the secondary role of aspect ratio as a separate quantity independent of dynamic similarity number, and, the variation in the four fundamental components of the radial pressure difference) are critically explained. The present study establishes, for the first time, that unlike the flow in a conventional turbomachine in which fluid friction plays only a detrimental role, fluid friction plays a dual role in a Tesla disc turbine—a detrimental role in increasing the radial pressure drop (thus tending to decrease the efficiency) and a beneficial role by providing the sole mechanism for power production. This dual role is comprehensively analyzed and quantified in this work. The balance between this dual role of fluid friction gives rise to the optimum values of dynamic similarity number and inlet tangential speed ratio that maximize efficiency.
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Ko¨ppel, Pascal, Christian Roduner, Peter Kupferschmied, and Georg Gyarmathy. "On the Development and Application of the Fast-Response Aerodynamic Probe System in Turbomachines—Part 3: Comparison of Averaging Methods Applied to Centrifugal Compressor Measurements." Journal of Turbomachinery 122, no. 3 (1999): 527–35. http://dx.doi.org/10.1115/1.1303820.
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Typically several hundred million data points arise from a comprehensive measurement campaign carried out in a centrifugal compressor test rig with the fast-response aerodynamic probe system (see Part 1). In order to obtain a maximum of information about the unsteady flow at any position in this turbomachine, the time-resolved data processing method has to be optimized. In contrast to the standard time-averaged flow measurements with pneumatic probes, the objective of fast-response aerodynamic probe measurements and of data processing is to extract novel information about crucial unsteady phenomena like turbulence, row-to-row interaction, modal or rotating stall, leakage flow effects, etc. In such cases, the simultaneous measurement of static and total pressures and flow vectors is of particular interest. Novel information means the analysis of averaged and time-resolved (wavelet) spectra, autocorrelations or time averages properly conserving physical fluxes, etc. Different averaging methods are applied to compress the time-dependent data measured by a one-sensor-probe (see Part 2) in a centrifugal compressor. Such results could be used for comparison with pneumatic sensor measurements and CFD calculations. The comparison of averaging methods includes the averaging theories by Traupel and by Dzung, which are compared to simple arithmetic time averaging. From there the specific stage work is calculated. In analyzing the time dependency, several ensemble-averaging procedures for flow pressure and velocity are utilized for separating deterministic from stochastic fluctuations, extracting blade row finger prints or investigating low-frequency surge type fluctuations. With respect to the selection and overall optimization of data processing methods, an overview of generic tools is given and the modularity of the processing procedures is discussed. [S0889-504X(00)01203-4]
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Drozdov, Aleksandr, and Alexey Rekstin. "Analysis of the velocity diagrams of impellers of centrifugal compressor stages after the preliminary design." MATEC Web of Conferences 245 (2018): 04004. http://dx.doi.org/10.1051/matecconf/201824504004.
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Preliminary design is an important stape in the development of centrifugal compressors and compressor stages. Basically for this purpose, various recommendations on the choice of the flow path dimensions are applied. Researchers of the Research and Development Laboratory “Gas dynamics of turbomachines” prof. Yu.B. Galerkin and A.F. Rekstin analyzed and summarized the dimensions of flow paths of 124 impellers. On the basis of this analysis, formulas were proposed for choosing the flow path dimensions of the centrifugal compressor stages, which were included in the preliminary design program. The formulas used are designed for relative Mach number of 0.7 and isentropic coefficient of 1.4. The correct application of these formulas for other Mach numbers and isentropic coefficient required development of an appropriate approach and algorithm for adjusting the height of the impeller blades at the outlet. Calculations of gas-dynamic characteristics using the Universal Modeling Method showed the need for selecting a coefficient that takes into account the influence of viscosity to obtain the required pressure characteristics of the compressor stage. This problem was also solved in the program of preliminary design. To check the quality of preliminary design, the results were verified using a non-viscous quasi-three-dimensional calculation program. Three stages were designed for parameters different to those used for development of preliminary design formulas. Analysis of the velocity diagrams of the impeller blades and distribution of meridional velocities showed good results of the preliminary design.
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Martynenko, Volodymir. "Comprehensive assessment of the strength of the composite fan blade of the main ventilation of the mine." Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines, no. 1 (December 31, 2021): 10–14. http://dx.doi.org/10.20998/2078-9130.2021.1.232865.
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The work is devoted to the development and calculation of the strength of a new composite fan blade of the main ventilation of the mine, including the static and modal analyzes, as well as the stability analysis. The studies took into account the pre-determined aerodynamic loads on the lateral surface of the blade airfoil. The research was carried out by means of the finite element analysis of the thin-walled airfoil structure using the theory of thick multilayer shells. Estimation of the static strength was performed using the Hashin strength criterion. Analysis of the airfoil shell buckling resistance under the action of bending aerodynamic loads was performed using the methods of the linear stability theory. The modal analysis was performed taking into account the prestressed state from the action of static loads. The analysis of the research results testifies to the sufficient static and dynamic strength of the composite airfoil and the possibility of its implementation in a real rotary machine with the correct design of the fastening between the metal part of the blade root and the composite airfoil. The method of designing and analyzing the strength of the fan blade composite airfoil can be used to create new composite elements of turbomachines: the correct selection of thicknesses of different parts of the airfoil allows obtaining a uniform design with rational use of material; the optimal location of the stiffeners inside the airfoil shell avoids its excessive displacement and stress and the buckling effects, as well as achieving the maximal detuning level from the bending natural frequencies of vibrations; the proposed integrated approach to the strength assessment, which takes into account the effect of aerodynamic loads on the blade airfoil in the static analysis and the prestressed state during the modal analysis can significantly improve the accuracy and correctness of calculations. The approach described in the paper is new for low-speed rotary machines, as at present there are no comprehensive methods for designing composite blades of fans and compressors, and there is no mention of specific examples of their implementation in the projects implemented by manufacturers.
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S., B. Alavi, Cerri G., Chennaoui L., Giovannelli A., and Mazzoni S. "Optimum Turbomachine Selection for Power Regeneration in Vapor Compression Cool Production Plants." March 1, 2015. https://doi.org/10.5281/zenodo.1100234.
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Power Regeneration in Refrigeration Plant concept has been analyzed and has been shown to be capable of saving about 25% power in Cryogenic Plants with the Power Regeneration System (PRS) running under nominal conditions. The innovative component Compressor Expander Group (CEG) based on turbomachinery has been designed and built modifying CETT compressor and expander, both selected for optimum plant performance. Experiments have shown the good response of the turbomachines to run with R404a as working fluid. Power saving up to 12% under PRS derated conditions (50% loading) has been demonstrated. Such experiments allowed predicting a power saving up to 25% under CEG full load.
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Chiapperi, Joseph, Edward Greitzer, and Choon S. Tan. "ATTRIBUTES OF BI-DIRECTIONAL TURBOMACHINERY FOR PUMPED THERMAL ENERGY STORAGE." Journal of Turbomachinery, September 16, 2022, 1–21. http://dx.doi.org/10.1115/1.4055647.
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Abstract In this paper we (i) present a methodology for determining the aerodynamic performance of bi-directional turbomachines for pumped thermal energy storage, i.e., turbomachines designed to operate as a compressor in one direction, and as a turbine in the opposite direction, (ii) carry out performance computations for such turbomachines, and (iii) propose principles for conceptual design of these devices. Focus is placed on using the energy storage cycle not only to identify the novel requirements placed on bi-directional turbomachines, but also to estimate the effect of these requirements on the efficiency of the energy storage process. In particular, the difference between aerodynamic loading in forward and backward operation causes the blading to work at incidences leading to performance below maximum efficiency, resulting in a lower round-trip efficiency. The description of the design principles includes determination of the number of stages, definition of non-dimensional parameters for blading selection, and optimization of two-dimensional blading for bi-directional operation. The assessment of stage count shows the relationship between relative Mach number, pressure ratio, and round-trip efficiency. The non-dimensional parameters are assessed through a bi-directional analogue to existing “Smith charts”, for the efficiency of single direction turbomachines, as a function of camber and stagger. The blade shape evaluation and optimization shows how the blade profile can be modified to address the requirements of a bi-directional turbomachine, enabling an increase in round-trip efficiency of 2 percentage points compared to a baseline double circular arc configuration.
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Tkacz, Eliza, Dorota Kozanecka, Zbigniew Kozanecki, and Jakub Łagodziński. "Oil-free bearing development for high-speed turbomachinery in distributed energy systems – dynamic and environmental evaluation." Open Engineering 5, no. 1 (2015). http://dx.doi.org/10.1515/eng-2015-0044.
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AbstractModern distributed energy systems, which are used to provide an alternative to or an enhancement of traditional electric power systems, require small size highspeed rotor turbomachinery to be developed. The existing conventional oil-lubricated bearings reveal performance limits at high revolutions as far as stability and power loss of the bearing are concerned. Non-conventional, oil-free bearings lubricated with the machine working medium could be a remedy to this issue. This approach includes a correct design of the machine flow structure and an accurate selection of the bearing type. Chosen aspects of the theoretical and experimental investigations of oil-free bearings and supports; including magnetic, tilting pad, pressurized aerostatic and hydrostatic bearings as well as some applications of oil-free bearing technology for highspeed turbomachinery; are described in the paper.
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Ciappi, A., A. Giorgetti, F. Ceccanti, and G. Canegallo. "Technological and economical consideration for turbine blade tip restoration through metal deposition technologies." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, November 13, 2019, 095440621988824. http://dx.doi.org/10.1177/0954406219888245.
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In the oil and gas industry, repair activities are critical to keep the maintenance costs of turbomachinery equipment down. Several repair technologies can be applied to various components of turbomachines. When dealing with gas turbines, the repair of turbine rotor blades has always been a very sensitive topic, given their critical application and their impact in terms of cost on the whole turbine lifecycle. Specifically, cracking and wearing of blade tips are some of the most common failure modes. Thus, the repair of these failure modes is of paramount importance, both for the original manufacturer as well as its aftermarket competitors. The present paper describes blade tip repair technologies from an original equipment manufacturer standpoint. Three different approaches are introduced and described for tip restoration. Laser cladding is presented first, since it is one of the most common technologies for this application, and then original equipment manufacturer which is currently being applied is presented. Then, cold metal transfer and direct metal laser melting technologies are investigated. A technologic and financial assessment is made to drive the technology selection for the turbine blades restoration.
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Visser, W. P. J., S. A. Shakariyants, and M. Oostveen. "Development of a 3 kW Microturbine for CHP Applications." Journal of Engineering for Gas Turbines and Power 133, no. 4 (2010). http://dx.doi.org/10.1115/1.4002156.
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Combined heat and power (CHP) concepts for small-scale distributed power generation offer significant potential for saving energy and reducing CO2 emissions. Microturbines are an interesting candidate for small CHP systems with advantages in terms of performance, size, noise, and costs. MTT is developing a 3 kW recuperated microturbine for micro CHP applications for large households and for truck combined APU-heating systems. To minimize costs, off-the-shelf automotive turbocharger technology has been used for the turbomachinery. During recent years, turbocharger turbomachinery performance and efficiencies have significantly increased, even for very small sizes. At the same time, efficient high-speed motor-generators have become available at relatively low prices. The development of a concept demonstrator started in May 2008. This program phase included a cycle analysis and component selection study around off-the-shelf turbomachinery, design of a custom combustor, recuperator and generator, and a test program. In this paper, results of the cycle definition, conceptual design and component matching study are presented. Next, the development of a detailed performance model is described and performance prediction results are given. Also, results of the test program and test analysis work are presented. Finally, from the conclusion of the demonstrator phase an outlook is given on the prototype design and performance, which will be the next phase of the development program.
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Frey, Christian, Benedict Geihe, and Laura Junge. "Analyzing Unsteady Turbomachinery Flow Simulations with Mixing Entropy." Journal of Turbomachinery, February 23, 2024, 1–34. http://dx.doi.org/10.1115/1.4064839.
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Abstract The prediction of unsteady aerodynamic loads is a central problem during the design of turbomachinery. A CPU-cost optimal setup of a harmonic balance simulation, however, requires the knowledge about relevant harmonics. For multi-stage configurations, the choice of harmonics is complicated by the fact that the interactions of disturbances with blade rows may give rise to a vast spectrum of harmonics that possibly have important modal content, e.g. Tyler-Sofrin modes. The aim of this paper is to show that the mixing entropy attributed to circumferential modes of a given harmonic can serve as a disturbance metric on the basis of which a criterion could be derived whether a certain harmonic should be included or not. The idea is based on the observation that the entropy due to the temporal and circumferential mixing of the flow at a blade row interface may be decomposed, up to third-order terms, into independent contributions from different frequencies and mode orders. For a given harmonic balance (and steady) flow result, the mixing entropy attributed to modes which are simply mixed out, rather than resolved in the neighboring row, is shown to be a natural indicator of a potential inaccuracy. We present important features of the mixing entropy for unsteady disturbances, in particular a close relationship to sound power for acoustic modes. The problem of mode selection in a 1.5-stage compressor configuration serves as a practical example to illustrate our findings.
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Mayorca, María A., Damian M. Vogt, Hans Mårtensson, and Torsten H. Fransson. "Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes." Journal of Turbomachinery 135, no. 1 (2012). http://dx.doi.org/10.1115/1.4006536.
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A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes which are different from the tuned in vacuo ones, due to mistuning, mode family interaction, or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses least square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application of this method on a transonic compressor blade shows that the method captures the aeroelastic properties well in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.
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Karaefe, Renan Emre, Pascal Post, Francesca di Mare, et al. "On Integrated Fluid Screening and Turbomachinery Design for Optimized Industrial Heat Pumps." Journal of Engineering for Gas Turbines and Power, September 27, 2022. http://dx.doi.org/10.1115/1.4055795.
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Abstract This work presents an approach to the contextual integration of fluid selection and compressor design for the cycle design of efficient industrial heat pumps. The vapor-compression cycle of an air-water heat pump operated at 42 °C source and 82 °C target temperature is investigated as a theoretical case study. An optimization study is performed, which includes the assessment of suitable refrigerants. Besides well-known single-component refrigerants, various binary mixtures are considered. The cycle optimization aims at simultaneously providing high cycle coefficient of performance and volumetric heating capacity. Cycle operation with the mixtures R-41/Trans-2-Butene (10, 90) mol % and CO2/R-161 (40, 60) mol % yields the highest values of these parameters, respectively. For further evaluation, centrifugal compressors operated with each of the two promising mixtures are designed with an in-house meanline program. In addition, the compressor design for the hydrofluoro-olefin refrigerant R-1234ze(Z) is considered as a reference. All designs are reviewed with respect to cycle as well as compressor design criteria and the applied methodology will assist designers in identifying key decision variables. The comprehensive design assessment suggests that CO2/R-161 (40, 60) mol % provides the best overall solution for an efficient cycle with a compact compressor design.
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San Andres, Luis, Jing Yang, and Rimpei Kawashita. "On the Effect of Clearance On the Leakage and Cavity Pressures in an Interlocking Labyrinth Seal Operating with and Without Swirl Brakes: Experiments and Predictions." Journal of Engineering for Gas Turbines and Power, October 14, 2020. http://dx.doi.org/10.1115/1.4048777.
Full textAbstract:
Abstract Gas labyrinth seals (LSs) improve turbomachinery operational efficiency and mechanical reliability by reducing secondary leakage. As interlocking labyrinth seals (ILSs) restrict more leakage than see-through LSs, attention is due to their performance.The paper reports measurements of the leakage and cavity pressures for a five teeth ILS configured with two clearances Cr = 0.3 mm and 0.13 mm. For the ILS with Cr = 0.3 mm, a first configuration is without a swirl brake, the second is with a swirl brake with 0° teeth pitch, and the third is with a swirl brake with teeth angled at 40° in the rotation direction. As to the ILS with Cr = 0.13 mm, it operates with a swirl brake with 0° teeth pitch and w/o rotor speed. The measurements and predictions show that the seal leakage is proportional to the inlet pressure, and is not affected by either shaft speed or the swirl brake configuration. Processing of the test data to consolidate the numerous leakage measurements delivers a nearly invariant flow factor for each clearance, and from this follows a unique orifice-like loss coefficient cd = 0.36 for Cr = 0.3 mm, and cd = 0.33 for Cr = 0.13 mm. This finding is remarkable as the earlier measurements obtained for the ILS with Cr = 0.2 mm also deliver a similar loss coefficient (cd = 0.36). The test data and predictions are of significant value to better the selection and design of gas labyrinth seals in turbomachinery.
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Morris, Nicholas, Ramin Rahmani, Homer Rahnejat, and Bharat Bhushan. "Air foil thrust and journal bearing coatings: A review." Journal of Tribology, July 16, 2024, 1–32. http://dx.doi.org/10.1115/1.4065986.
Full textAbstract:
Abstract Surfaces of air foil thrust and journal bearings in high-speed turbomachinery are coated to improve their operational integrity, particularly when the aerodynamic load carrying capacity is reduced during instances of startup and shutdown. Surface coatings, as protective barriers in air foil bearings, can mitigate the adverse effects of direct surface interactions on such occasions. This paper provides an in-depth review of the body of important research conducted for study of coated air foil thrust and journal bearings, highlighting the state of the art in coating technology. The review features the role of composite coatings, designed to provide favourable thermal, mechanical, and frictional characteristics. The paper also highlights the trends in selection of coatings for air foil bearings pertinent to desired thermomechanical performance.