Academic literature on the topic 'Rotary steady air injection'
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Journal articles on the topic "Rotary steady air injection"
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Benhegouga, Islem, and Ce Yang. "Steady Air Injection Flow Control in Centrifugal Compressor." Applied Mechanics and Materials 138-139 (November 2011): 471–77. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.471.
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In the present work steady air injection upstream of the leading edge was used in a centrifugal compressor, Whose preliminary design of compressor injection systems can be modeled by a geometrical relationship between user-specified yaw angle and resulting blade incidence angle based on simple velocity triangles, the error between the best yaw angle obtained from this relationship and that obtained from numerical simulation is less than 3%. To reveal the mechanism, steady numerical simulations were performed on high pressure ratio centrifugal compressor rotor operated with a rotor tip speed of 586 m/s. Parametric studies of the injection yaw angle was performed to determine the configuration that provide the best steady results for the compression systems studied in this work. The injectors were placed at short distance (ten percent of the inlet tip radius upstream of the compressor face) the objective of this was to achieve maximum control over the leading edge flow by varying individual injection parameters. The injection angle, α, was fifteen while the yaw angle, β, was parametrically varied. The results show that at design speed (n= 50 000 r/min) with injection flow rate equal to 3% of the main flow rate and 25 degree air injection yaw angle can lower the mass flow rate at stall for approximately 7.5%.
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Jia, Guohai, Lijun Li, and D. M. Zhang. "Effect Analysis on Combustion and Emission Characteristics of a Rotary Burner Fueled by Biomass Pellet Fuel." Journal of Chemistry 2020 (July 21, 2020): 1–12. http://dx.doi.org/10.1155/2020/3618382.
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A biomass pellet rotary burner was chosen as the research object, in order to study the influence of excess air coefficient on the combustion phenomenon of biomass rotary burner, the finite element simulation model of a biomass rotary burner was established, and simulation results of a biomass rotary burner were verified by the experiment. The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in a steady-state condition, and the effect of excess air coefficient on temperature field and component concentration field in biomass rotary burner was analyzed. The results show that the flue gas flow rate inside the burner gradually increases with the increase of air velocity, the area with large temperature is mainly concentrated in the middle region of the rotary burner, and the maximum combustion temperature also appeared in the middle region of the combustion chamber, and the formation area of CO decreases with the increase of excess air coefficient. CO2 is mainly concentrated in the middle region of the burner, and the CO2 generating region decreases with the increase of excess air coefficient. The experimental value of the combustion temperature of the biomass rotary burner is in good agreement with the simulation results.
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Zhang, Cong Peng, Mei Bo Li, and Xue Ke Luo. "Thermal Characteristics Analysis of Aerostatic Direct Drive Rotary Stage." Advanced Materials Research 655-657 (January 2013): 287–91. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.287.
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A precision air bearing rotary stage driven by direct-driven motor is proposed. The structural characteristic of the rotary system is introduced, and the mechanism of structural thermal deformation and heat dissipation of aerostatic direct drive rotary stage were analyzed. The simulation models of static and transient temperature field are built, and thermal-structure coupled filed is calculated. The internal steady thermal field diagram and key nodes temperature curve of the rotary stage are obtained. Based on the temperature analysis results, the rotary stage structural deformation is established. The cooling method is provided, and result shows that the cooling way is effective.
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Ben Noah, Ilan, and Shmulik P. Friedman. "Continuum Modeling of Steady Air Injection into Partially Saturated Soils." Vadose Zone Journal 14, no. 9 (September 2015): vzj2014.12.0170. http://dx.doi.org/10.2136/vzj2014.12.0170.
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Lu, Xingen, Wuli Chu, Junqiang Zhu, and Zhiting Tong. "Numerical and Experimental Investigations of Steady Micro-Tip Injection on a Subsonic Axial-Flow Compressor Rotor." International Journal of Rotating Machinery 2006 (2006): 1–11. http://dx.doi.org/10.1155/ijrm/2006/71034.
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Steady tip injection has been demonstrated to be an effective means of extending the stable operating range of a tip-critical compressor. This study presents a state-of-the-art design for the tip injection through the casing with flush-mounted inclined holes and the effectiveness of steady micro-air injection to enhance stability in a subsonic axial-flow compressor rotor using an external-air supply. For the tested rotor, experimental results demonstrate that at 53% design speed, the stalling mass flow can be reduced by 7.69% using an injected mass flow equivalent to 0.064% of the annulus flow. Time-dependent CFD simulations were conducted to identify the physical mechanic that accounts for the beneficial effects of the steady micro-air injection on the performance and stability of the compressor. Detailed analyses of the flow visualization at the tip have exposed the different tip flow topologies between the cases without tip injection and with tip injection. It was found that the primary stall margin enhancement afforded by the steady micro-air injection is a result of the tip-clearance flow manipulation. The repositioning of the tip-clearance vortex further towards the trailing edge of the blade passage and delaying the movement of incoming/tip-clearance flow interface to the leading edge plane are the physical mechanisms responsible for extending the compressor stall margin.
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WARDENIER, K., and E. VAN DEN BULCK. "Steady-State Waste Combustion and Air Flow Optimization in a Field Scale Rotary Kiln." Environmental Engineering Science 14, no. 1 (January 1997): 43–54. http://dx.doi.org/10.1089/ees.1997.14.43.
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Benhegouga, Islem, and Yang Ce. "Steady Air Injection Flow Control Parameters in a Transonic Axial Compressor." Research Journal of Applied Sciences, Engineering and Technology 5, no. 4 (February 1, 2013): 1441–48. http://dx.doi.org/10.19026/rjaset.5.4885.
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Tian, Changqing, Chunpeng Dou, Xianting Li, and Yunfei Liao. "Experimental investigation on the steady-state performance and piston stroke length control of a variable displacement wobble plate compressor." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 2 (February 1, 2005): 271–81. http://dx.doi.org/10.1243/095440705x5911.
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The aim of this paper is to find out the steady-state performance and piston-stroke-length control behaviour of a variable displacement wobble-plate compressor for an automotive air-conditioning system by experimental investigation. First, a new method and device to measure the piston stroke length of the variable displacement compressor has been developed, with which the test bench for the variable displacement compressor has been set up. Second, the steady-state performance of the variable displacement compressor, such as the relative volumetric efficiency and the relative isentropic efficiency at partial piston stroke length, has been obtained. The influence of the work condition and compressor rotary speed on the relative volumetric efficiency can be neglected according to the test data. Finally, the critical wobble-plate case pressure is proposed in this paper to judge whether the piston stroke length will change or not. The critical wobble-plate case pressure when the piston stroke length decreases is greater than that when the piston stroke length increases, which is less influenced by the piston stroke length itself from the test data. The higher the compressor discharge pressure or rotary speed, the greater the critical wobble-plate case pressure. The piston stroke length can be adjusted automatically along with the air-conditioning load when the compressor rotary speed or air conditioning load changes.
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Nie, Chaoqun, Gang Xu, Xiaobin Cheng, and Jingyi Chen. "Micro Air Injection and Its Unsteady Response in a Low-Speed Axial Compressor." Journal of Turbomachinery 124, no. 4 (October 1, 2002): 572–79. http://dx.doi.org/10.1115/1.1508383.
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A new approach, steady micro air injection from the casing, is proposed to improve the stability of a three-stage low-speed axial compression system. Although the injection rate is designated to be only a few ten thousandth of the compressor flow rate, such an injection is able to trigger the unsteady response and thus lower the mass flow rate at stall for up to 5.83%. At the same time, it keeps the steady compressor characteristic with no injection unchanged. In order to verify that the compressor response is indeed unsteady, experiments at various injection configurations are performed, which include different injection angles, axial gaps between injector and blade leading edge, radial penetration of injector and the amount of injected air. Evidences of the unsteady response are further demonstrated through dynamic signal analysis using a wavelet-based method to show the behavior of early flow disturbances under the influence of injection. Numerical analyses performed at near stall condition show that the tip clearance vortices do response to the micro-injection, and thus delay the inception of stall.
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Guettler, Nico, Philipp Knee, Qiaoyan Ye, and Oliver Tiedje. "Initial droplet conditions in numerical spray painting by electrostatic rotary bell sprayers." Journal of Coatings Technology and Research 17, no. 5 (June 24, 2020): 1091–104. http://dx.doi.org/10.1007/s11998-020-00352-1.
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Abstract In computational fluid dynamics, the modeling of paint application processes by electrostatic rotary bell sprayer is mostly performed using an Euler–Lagrange approach. The initial conditions of the discrete phase—position, velocity, size, and charge—have an essential influence on the resulting film thickness distribution and the total charge transferred to the object. Typically, so-called injection models are used to specify these initial conditions, whereby the determination of the injection model coefficients is crucial. In this paper, a framework is proposed that combines experimental input data, an injection model, and a metamodel-based optimization. The painting tests for the generation of input and validation data were carried out in a technical center in the industrial standard. The simulations were performed using ANSYSFluent. Initial droplet conditions could efficiently be determined via the framework so that the painting-specific objectives were achieved with reasonable accuracy. In addition to the framework, a turbulence study of the strongly swirled shaping air of this atomizer was carried out, whereby a substantial underestimation of the axial air velocity was found in the turbulence models being investigated. The initial droplet conditions were also used in this study to draw conclusions about the accuracy of the airflow simulation. The proposed framework can be adapted to other solvers and efficiently finds injection model coefficients for other paint applicators.
Dissertations / Theses on the topic "Rotary steady air injection"
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Azzam, Tarik. "Aérodynamique et contrôle de l'écoulement de jeu dans un ventilateur axial obtenu par rotomoulage." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0080/document.
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Aujourd’hui, la fabrication des turbomachines est conditionnée par des normes de plus en plus restrictives. L'enjeu industriel pour les chercheurs est d'envisager des solutions optimales visant à réduire les sources de perte d'énergie, d'instabilité et du bruit, en particulier l'écoulement de jeu (débit de fuite). Des actions préliminaires ont été élaborées à Arts & Métiers ParisTech sur le rotomoulage du ventilateur axial de refroidissement d'automobile. L'idée de ce travail est d'utiliser la forme creuse induite par le rotomoulage afin de l'exploiter dans le controle de l'écoulement de jeu radial par soufflage rotatif. Pour cela, la virole comporte des trous d'injection orientés de façon à réduire simultanément le débit de fuite et le couple. Dans ce travail, trois parties ont été traité. La première concerne la réalisation du ventilateur par rotomoulage. La deuxième concerne l'étude expérimentale menée dans le banc d'essai ISO 5801. Cette étude comporte la réalisation d'un montage dédié au contrôle par soufflage rotatif, la métrologie menée pour la détermination des performances globales et la caractérisation de la vitesse axiale du sillage proche. La troisième partie traite la modélisation numérique des conditions expérimentales rentables ensuite l'extrapolation du travail vers des taux d'injection importants. Pour ce dernier, on arrive à annuler le débit de fuite avec un gain considérable du couple mettant ainsi le ventilateur en autorotationNowadays, the manufacture of turbomachinery is conditioned by more and more restrictive rules. The industrial challenge for researchers has to consider optimal solutions to reduce sources of energy loss, instability and noise, particularly the tip clearance flow (leakage flow rate). Preliminary actions have been developed at Arts & ParisTech on rotational molding process used for the automobile cooling axial fan. The idea of this work is to use the hollow shape induced by rotational molding process in order to exploit it in the control of tip clearance flow through rotary steady air injection. For this, the shroud ring is composed of injection holes oriented in such away to reduce both of leakage flow rate and the torque. In this work, the thesis focuses on three parts. The first concerns the build of the fan by rotational molding process. The second concerns the experimental study carried out in the ISO 5801 test bench. This study involves the realization of drive system dedicated to rotary steady air injection, metrology for performance determination and the characterization of the near wake axial velocity. The third part deals with the numerical modeling of efficient experimental conditions, then the extrapolation of work towards high injection rates. For this latter, it is possible to cancel leakage flow rate with a considerable gain of the torque thus putting the fan in autorotation
Books on the topic "Rotary steady air injection"
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G, Guzman A., U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Regulatory Applications., and University of Arizona. Dept. of Hydrology and Water Resources., eds. Summary of air permeability data from single-hole injection tests in unsaturated fractured tuffs at the Apache Leap research site: Results of steady-state test interpretation. Washington, DC: Division of Regulatory Applications, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1996.
Find full textConference papers on the topic "Rotary steady air injection"
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Chi, John N. "Unsteady Loading of Rotor Blades by High Pressure Air Injection." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10465.
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A gas turbine engine consists of three primary components: a compressor, a combustion chamber, and a turbine. The operating range, performance, and reliability of gas turbine engines are limited by aerodynamic instabilities that occur in the compressor at low mass flow rates. Two of such compressor instabilities are rotating stall and surge. The stabilization of compression systems by means of active control has been demonstrated on several research compressors using different actuators such as inlet guide vanes, bleed valves, and air injection to manipulate the compressor flow field. This paper presents experimental and model simulated results of the steady and unsteady behaviors of air injection in high speed axial flow compressors that can be used for feasibility studies and control algorithm development. A control oriented model of the unsteady response of the transonic compressor blade rows to steady air injection is presented. This behavior was modeled by one-dimensional flow in a diffusing passage subject to a time varying inlet flow condition in the rotor relative reference frame. The one-dimensional model was then used to provide simplified input boundary conditions for a computational fluid dynamic (CFD) model that predicted aerodynamic loading on a transonic rotor blade due to steady air injection. The aerodynamic loading on a transonic rotor blade due to steady air injection were then simulated from the computational fluid dynamic (CFD) model. The simulation results for an evenly circumferentially spaced discrete number of jet actuators show that the fluctuating loading due to jet injection are non-sinusoidal and periodic. Total pressure, total temperature, and absolute flow angle survey measurements that map out the effect of high pressure air injection on a transonic compressor rotor for different levels of steady injection and different orientations are also presented.
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Choi, Dong-Chun, David L. Rhode, and Robert W. Sunshine. "Injection Coolant Isolation Curtain to Reduce Turbine Ingress Heating." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-69090.
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The advanced strategy to reduce the turbine ingress heating and thus the coolant requirement by injecting a “coolant isolation curtain” was developed numerically using a 3-D CFD model under steady state conditions. The coolant isolation curtain was applied under the nozzle guide vane platform for the forward cavity of a turbine stage of a large gas turbine engine. Specifically, the isolation curtain serves to isolate the hot mainstream gas from the turbine outer region. For comparison purposes, when the baseline design and the injection curtain design have the same total coolant mass flow, the maximum temperature T*max of the injection curtain design was reduced by 0.23, 0.12 and 0.12, respectively, for the outer cavity, outer rotor adiabatic wall and outer stator adiabatic wall compared to that of the baseline design. Upon adjusting the feed slot coolant of the baseline design to match the outer cavity T*max, for example, of the injection curtain design, the reduction of dimensionless total coolant per stage from applying the injection curtain was estimated as 0.0038. Also a more uniform adiabatic wall temperature distribution along the outer rotor and stator surfaces was observed by using the coolant isolation curtain.
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Horn, Wolfgang, Klaus-Ju¨rgen Schmidt, and Stephan Staudacher. "Effects of Compressor Tip Injection on Aircraft Engine Performance and Stability." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27574.
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This analytical study discusses the system aspects of active stability enhancement using mass flow injection in front of the rotor blade tip of a high pressure compressor. Tip injection is modeled as a recirculating bleed in a performance simulation of a commercial turbofan engine. A map correction procedure accounts for the changes in compressor characteristics caused by injection. The correction factors are derived from stage stacking calculations which include a simple correlation for stability enhancement. The operational characteristic of the actively controlled engine is simulated in steady and transient states. The basic steady-state effect consists of a local change in mass flow and a local increase in gas temperature. This alters the component matching in the engine. The mechanism can be described by the compressor-to-turbine flow ratio and the injection temperature ratio. Both effects reduce the cycle efficiency resulting in increased turbine temperature and fuel consumption at constant thrust. The negative performance impact becomes negligible if compressor recirculation is only employed at transient part power and if valves remain closed at steady-state operation. Detailed calculations show that engine handling requirements and temperature limits will still be met. Tip injection increases the high pressure compressor stability margin substantially during critical maneuvers. The proposed concept in combination with an adequate control logic offers promising benefits at transient operation, leading to an improvement potential for overall engine performance.
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Schuepbach, P., R. S. Abhari, M. G. Rose, T. Germain, I. Raab, and J. Gier. "Effects of Suction and Injection Purge-Flow on the Secondary Flow Structures of a High-Work Turbine." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50471.
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In high-pressure turbines, a small amount of air is ejected at the hub rim seal, to cool and prevent the ingestion of hot gases into the cavity between the stator and the disk. This paper presents an experimental study of the flow mechanisms that are associated with injection through the hub rim seal at the rotor inlet. Two different injection rates are investigated: nominal sucking of −0.1% of the main massflow and nominal blowing of 0.9%. This investigation is executed on a one-and-1/2-stage axial turbine. The results shown here come from unsteady and steady measurements, which have been acquired upstream and downstream of the rotor. The paper gives a detailed analysis of the changing secondary flow field as well as unsteady interactions associated with the injection. The injection of fluid causes a very different and generally more unsteady flow field at the rotor exit near the hub. The injection causes the turbine efficiency to deteriorate by about 0.6%.
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Strazisar, Anthony J., Michelle M. Bright, Scott Thorp, Dennis E. Culley, and Kenneth L. Suder. "Compressor Stall Control Through Endwall Recirculation." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54295.
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Experiments that demonstrate the use of endwall recirculation to control the stall of transonic compressor stages are described. Endwall recirculation of a compressor stage is implemented by bleeding air from the casing downstream of a stator blade row and injecting the air as a wall jet upstream of a preceding rotor blade row. The bleed ports, injection ports, and recirculation channels are circumferentially discrete, and occupy only 20–30% of the circumference. The development of compact wall-jet injectors is described first. Next, the results of proof-of-concept steady recirculation tests on a single-stage transonic compressor are presented. Finally, the potential for using endwall recirculation to increase the stability of transonic highly-loaded multistage compressors is demonstrated through results from a rig test of simulated recirculation driving both a steady injected flow and an unsteady injected flow commanded by closed-loop active control during compressor operation at 78–100% of design speed. In this test air from an external source was injected upstream of several rotor blade rows while compressor bleed was increased by an amount equivalent to the injected massflow. During closed loop control, wall static pressure fluctuations were monitored and the injected flow rate was controlled to reduce the stalling mass flow. The use of wall jet injection to study the dynamics of transonic compressor stages is also discussed.
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Neuhaus, Lars, Olaf Wiederhold, Wolfgang Neise, Lars Enghardt, Rudibert King, and Marius Swoboda. "Active Flow Control to Improve the Aerodynamic Performance of Axial Turbomachines." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60008.
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Axial turbomachines have a radial gap between the casing and the rotor blades. The static pressure difference between the suction and the pressure side of the impeller blades produces a secondary flow over the tip of the rotor blades. This tip clearance flow is important for the aerodynamic performance of the fan. Fan pressure and efficiency drop, and the usable range of the performance characteristics is diminished as the rotor flow is stalled at low flow rates. Previous investigations have shown that one method for increasing the aerodynamic performance is to control the flow in the tip clearance gap via air injection into the gap. The goal of this paper is to compare the different effects of steady and unsteady air injection on the aerodynamic performance curves and to implement various closed-loop extremum-seeking control algorithms. The main purpose of these active flow control methods is to stabilize the flow at operating points, where it is stalled otherwise. To compare the effect of steady and unsteady air injection, the aerodynamic performance curves (fan pressure rise and efficiency) were measured for different sets of frequencies with the air injection rate held constant. To control the air injection rate automatically and to find optimal actuation parameters, a SISO-extremum-seeking control algorithm was applied. For the improvement of the control performance, the controller was extended by a slope-seeker. Moreover, an extended Kalman filter was used to speed up the control via a faster slope detection to accelerate the estimation of the local gradient of the static input-output map of the process. This new approach led to an almost fivefold increase in closed-loop control speed.
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Vilmin, S., E. Lorrain, Ch Hirsch, and M. Swoboda. "Unsteady Flow Modeling Across the Rotor/Stator Interface Using the Nonlinear Harmonic Method." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90210.
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The paper presents results of the incorporation of the harmonic nonlinear method into an existing turbomachinery Navier-Stokes code. This approach, introduced by He and Ning in 1998, can be considered as a bridge between classical steady state and full unsteady calculations, providing an approximate unsteady solution at affordable calculation costs. The unsteady flow perturbation is Fourier decomposed in time, and by a casting in the frequency domain transport equations are obtained for each time frequency. The user controls the accuracy of the unsteady solution through the order of the Fourier series. Alongside the solving of the time-averaged flow steady-state equations, each frequency requires the solving of two additional sets of conservation equations (for the real and imaginary parts of each harmonic). The method is made nonlinear by the injection of the so-called deterministic stresses, resulting from all the solved frequencies, into the time-averaged flow solver. Because of the transposition to the frequency domain, only one blade channel is required like a steady flow simulation. The presented method also features a new improved treatment that enhances the flow continuity across the rotor/stator interface by a reconstruction of the harmonics and the time-averaged flow on both sides of the interface. A non-reflective treatment is applied as well at each interface. Validation for analytical and turbomachinery test cases are presented. In particular, results are compared between the harmonic method, steady-state mixing plane and full unsteady calculations. The comparison with the reference full unsteady calculation provides a quantitative indication of the accuracy of the approach, as well as the significant gain in CPU time, whereas the comparison with classical quasi-steady state solutions indicates the gain of accuracy. A multistage compressor flow is also presented to show the capabilities of the method.
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Boncinelli, P., N. Maceli, A. Arnone, and E. Rossi. "Geometrical Effects and Coolant Injection Impact on the Performance of an HP Transonic Heavy-Duty Turbine Stage." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54178.
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A numerical study of a high pressure transonic axial turbine stage for heavy-duty applications was performed. Attention was focused on assessing the aerodynamic impact of coolant injection and geometrical features, such as slots, fillets and clearances, on stage performance. First, stator and rotor blade rows were separately studied to single out the main modeling factors. Results showed the way each factor affects the performance of the blade. Influence coefficient evaluation was performed with screening techniques, such as DOE (Design Of Experiments) methods. Physical mechanisms responsible for performance decay were investigated by analyzing the secondary flow structure. After the main modeling factors had been selected and included, a 3D steady analysis of the full-stage configuration was carried out at both design and off-design conditions. Results were also compared with experimental data available from GE-Oil & Gas Nuovo Pignone. The performed analysis showed endwall fillets and coolant injection at the trailing edge slot as the most significant factors for efficiency for both stator and rotor blades. Coolant injection at the showerhead and at the suction and pressure side holes, and the geometrical slot turned out to affect blade-row performance to a smaller extent. Comparison with experimental data showed that a substantial improvement in both stage efficiency and loading factor prediction capability was obtained.
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Spakovsky, Z. S. "Backward Traveling Rotating Stall Waves in Centrifugal Compressors." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30379.
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Rotating stall waves that travel against the direction of rotor rotation are reported for the first time and a new, low-order analytical approach to model centrifugal compressor stability is introduced. The model is capable of dealing with unsteady radially swirling flows and the dynamic effects of impeller-diffuser component interaction as it occurs in centrifugal compression systems. A simple coupling criterion is developed from first principles to explain the interaction mechanism important for system stability. The model findings together with experimental data explain the mechanism for first-ever observed backward traveling rotating stall in centrifugal compressors with vaned diffusers. Based on the low-order model predictions, an air injection scheme between the impeller and the vaned diffuser is designed for the NASA Glenn CC3 high-speed centrifugal compressor. The steady air injection experiments show an increase of 25% in surge-margin with an injection mass flow of 0.5% of the compressor mass flow. In addition, it is experimentally demonstrated that this injection scheme is robust to impeller tip-clearance effects and that a reduced number of injectors can be applied for similar gains in surge-margin. The results presented in this paper firmly establish the connection between the experimentally observed dynamic phenomena in the NASA CC3 centrifugal compressor and a first principles based coupling criterion. In addition, guidelines are given for the design of centrifugal compressors with enhanced stability.
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Tong, Zhiting, Feng Lin, Jingyi Chen, and Chaoqun Nie. "The Self-Induced Unsteadiness of Tip Leakage Vortex and Its Effect on Compressor Stall Inception." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27010.
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The self-induced unsteadiness of tip leakage vortex (TLV), which appears in a compressor rotor working in a range of operating points on its characteristics, from wide-open throttle all the way to the stall limit, is investigated experimentally. The research aims are twofold, to clarify the three modes in TLV development process through experimental evidences and to explore the effect of this in-blade TLV unsteadiness on stall inception. In the first half of the paper, in order to detect the unsteadiness and ensure its existence in the experimental environment (not just in computational results), phase-locked Mean and Root-Mean-Square (RMS) contours are used to track the time-averaged trajectories of the TLV, while a power spectral density (PSD) analysis provides a means to identify the magnitude and the frequency of the oscillation. With all of the above, the three modes of the TLV development, which are steady, in-blade unsteady and cross-blade unsteady TLV, can be clearly demonstrated. In the second half of this paper, various tip jet injections are applied to test the effects of the unsteady TLV on stall inception. It is found that a spike stall precursor is originated from circumferential locations where the strongest unsteady TLV are. At those locations, tip jet injections that are designated to directly alter the characteristics of TLV improve the stall margin effectively. Further, the injections are arranged over the rotor tip in difference axial locations and switched on at different points of compressor characteristic, demonstrating that if the injection misses the tip vortices or interferes with TLV too late, little or even no improvement in stall margin can be gained. These results show that the unsteady TLV are closely related to spike stall inception in this single rotor, which implies that the initiation of compressor stall could be manipulated by properly altering the characteristics of TLV unsteadiness.
Reports on the topic "Rotary steady air injection"
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Guzman, A. G., A. M. Geddis, M. J. Henrich, C. F. Lohrstorfer, and S. P. Neuman. Summary of air permeability data from single-hole injection tests in unsaturated fractured tuffs at the Apache Leap Research Site: Results of steady-state test interpretation. Office of Scientific and Technical Information (OSTI), March 1996. http://dx.doi.org/10.2172/219309.
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