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Literatura académica sobre el tema "Inlet distortions"

Autor: Grafiati

Publicado: 7 de diciembre de 2024

Última modificación: 5 de julio de 2025

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Artículos de revistas sobre el tema "Inlet distortions"

Ariga, I., S. Masuda, and A. Ookita. "Inducer Stall in a Centrifugal Compressor With Inlet Distortion." Journal of Turbomachinery 109, no. 1 (1987): 27–35. http://dx.doi.org/10.1115/1.3262066.

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The effects of inlet distortion on the inducer stall in a centrifugal compressor are investigated. Cases of both radial and circumferential distortion are investigated. It is shown that the rotating stall onset is amplified by radial distortions, and restrained by circumferential distortions. These results are compared with calculations based on the small disturbance theory. The authors find that the stall onset is governed by the characteristic parameters related to the lower flow rate region for radial distortions, but affected by those of the higher flow rate region for circumferential distortion. It is shown that the process of stall is different for each distortion pattern. Existence of inlet distortion reduces compressor performance characteristics and strongly influences the stability margin.

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Lowe, K. Todd. "Laser velocimetry for turbofan inlet distortion applications." Aircraft Engineering and Aerospace Technology 92, no. 1 (2020): 20–26. http://dx.doi.org/10.1108/aeat-11-2018-0285.

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Purpose The purpose of this paper is to assess state-of-the-art techniques for quantifying flow distortion in the inlets of turbofan engines, particularly with respect to the prospects for future flight applications. Design/methodology/approach To adequately characterize the flow fields of complex aircraft inlet distortions, the author has incorporated laser velocimetry techniques, namely, stereoscopic particle image velocimetry (PIV) and Doppler velocimetry based on filtered Rayleigh scattering (FRS), into inlet distortion studies. Findings Overall, the results and experience indicate that the pathway for integration of FRS technologies into flight systems is clearer and more robust than that of PIV. Practical implications While always a concern, the topic of inlet distortion has grown in importance as contemporary airframe designers seek extremely compact and highly integrated inlets. This research offers a means for gaining new understanding of the in situ aerodynamic phenomena involved with complex inlet distortion. Originality/value This paper presents unique applications of turbofan inlet velocimetry methods while providing an original assessment of technological challenges involved with progressing advanced velocimetry techniques for flight measurements.

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Pazur, W., and L. Fottner. "The Influence of Inlet Swirl Distortions on the Performance of a Jet Propulsion Two-Stage Axial Compressor." Journal of Turbomachinery 113, no. 2 (1991): 233–40. http://dx.doi.org/10.1115/1.2929091.

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Aeroengine intakes containing S-shaped diffusers produce different types of inlet swirl distortions and essentially a combination of a twin swirl and a bulk swirl. The main object of this investigation was to assess the influence of inlet swirl distortions on the performance of a transonic two-stage axial compressor installed in a turbo jet bypass engine Larzac 04. A typical inlet swirl distortion was simulated by a delta-wing in front of the engine. An experimental method was investigated to measure the performance map of the installed low-pressure compressor for different engine operating lines. The influence of an inlet swirl distortion with different strengths on the performance map of the compressor was investigated experimentally. It is shown that the performance parameters decrease and a temperature distortion is generated behind the compressor. As the basis of the theoretical investigations of the performance map, including inlet swirl distortions, a computing model considering four compressors working in parallel was established. The model is based on the idea that an inlet swirl distortion can be substituted by two fundamental types of swirl components, i.e., a bulk swirl corotating, and a bulk swirl counterrotating to the revolution of the compressor. Computed performance maps of the compressor will be discussed and compared with the experimental data.

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Pečinka, Jiří, Gabriel Thomas Bugajski, Petr Kmoch, and Adolf Jílek. "JET ENGINE INLET DISTORTION SCREEN AND DESCRIPTOR EVALUATION." Acta Polytechnica 57, no. 1 (2017): 22–31. http://dx.doi.org/10.14311/ap.2017.57.0022.

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Total pressure distortion is one of the three basic flow distortions (total pressure, total temperature and swirl distortion) that might appear at the inlet of a gas turbine engine (GTE) during operation. Different numerical parameters are used for assessing the total pressure distortion intensity and extent. These summary descriptors are based on the distribution of total pressure in the aerodynamic interface plane. There are two descriptors largely spread around the world, however, three or four others are still in use and can be found in current references. The staff at the University of Defence decided to compare the most common descriptors using basic flow distortion patterns in order to select the most appropriate descriptor for future department research. The most common descriptors were identified based on their prevalence in widely accessible publications. The construction and use of these descriptors are reviewed in the paper. Subsequently, they are applied to radial, angular, and combined distortion patterns of different intensities and with varied mass flow rates. The tests were performed on a specially designed test bench using an electrically driven standalone industrial centrifugal compressor, sucking air through the inlet of a TJ100 small turbojet engine. Distortion screens were placed into the inlet channel to create the desired total pressure distortions. Of the three basic distortions, only the total pressure distortion descriptors were evaluated. However, both total and static pressures were collected using a multi probe rotational measurement system.

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Hah, C., D. C. Rabe, T. J. Sullivan, and A. R. Wadia. "Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor." Journal of Turbomachinery 120, no. 2 (1998): 233–46. http://dx.doi.org/10.1115/1.2841398.

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The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of eight periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier–Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20 percent of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

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Fang, Yibo, Dakun Sun, Xu Dong, and Xiaofeng Sun. "Effects of Inlet Swirl Distortion on a Multi-Stage Compressor with Inlet Guide Vanes and Stall Margin Enhancement Method." Aerospace 10, no. 2 (2023): 141. http://dx.doi.org/10.3390/aerospace10020141.

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Inlet swirl distortion is generally considered as a type of velocity distortion, and inlet guide vanes (IGVs) are widely used in the multi-stage compressor of aero-engines to eliminate the tangential velocity of the swirl flow. However, few studies have explored whether there still exists some negative influence of inlet swirl distortion on the compressor, even after the installation of IGVs. Therefore, in this study, the influence of various types of inlet swirl distortions on a multi-stage compressor with the installation of IGVs is investigated. A swirl distortion generator installed in the inlet duct was designed to produce various types of swirl flow patterns. When the distortion intensity increased to some degree, there still existed a decrease in the compressive capability and an obvious additional efficiency loss. The inlet twin swirl distortion was accompanied by total pressure distortion, so even with the installation of IGVs, there was still a significantly negative influence on the performance of the multi-stage compressor, especially the stall margin. Subsequently, to improve the stall margin under inlet swirl distortion, the stall precursor-suppressed (SPS) casing treatment was installed in the first stage of the multi-stage compressor. It could enhance the stall margin of the compressor with no obvious change in the characteristic curves and no additional efficiency loss under various types of inlet swirl distortions, and its mechanism was verified by capturing the dynamic pressure characteristics.

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Leinhos, Dirk C., Norbert R. Schmid, and Leonhard Fottner. "The Influence of Transient Inlet Distortions on the Instability Inception of a Low-Pressure Compressor in a Turbofan Engine." Journal of Turbomachinery 123, no. 1 (2000): 1–8. http://dx.doi.org/10.1115/1.1330271.

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While studies on compressor flow instabilities under the presence of inlet distortions have been carried out with steady distortions in the past, the investigation presented here focuses on the influence of transient inlet distortions as generated by variable geometry engine intakes of super- and hypersonic aircraft on the characteristic and the nature of the instability inception of a LPC. The flow patterns (total pressure distortion with a superimposed co- or counterrotating swirl) of the distortions are adopted from a hypersonic concept aircraft. A LARZAC 04 twin-spool turbofan was operated with transient inlet distortions, generated by a moving delta wing, and steady total pressure distortions starting close to the LPC’s stability limit until it stalled. High-frequency pressure signals are recorded at different engine power settings. Instabilities are investigated with regard to the inception process and the early detection of stall precursors for providing data for a future stability control device. It turned out that the transient distortion does not have an influence on the surge margin of the LPC compared to the steady distortion, but that it changes the nature of stall inception. The pressure traces are analyzed in the time and frequency domain and also with tools like Spatial FFT, Power Spectral Density, and Traveling Wave Energy. A Wavelet Transformation algorithm is applied as well. While in the case of clean inlet flow, the compressor exhibits different types of stall inception depending on the engine speed, stall is always initiated by spike-type disturbances under the presence of steady or transient distortions. Modal disturbances are present in the mid-speed range that do not grow into stall, but rather interact with the inlet flow and produce short length scale disturbances. The obtained early warning times prior to stall are adversely affected by transient distortions in some cases. The problem of appropriate thresholding becomes evident. The best warning times have been acquired using a statistical evaluation of the Wavelet coefficients, which might be promising to apply in a staged active control system. This system could include different phases of detection and actuation depending on the current precursor.

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Ng, Eddie Yin-Kwee, Ningyu Liu, Hong Ngiap Lim, and Daniel Tan. "An Improved Integral Method for Prediction of Distorted Inlet Flow Propagation in Axial Compressor." International Journal of Rotating Machinery 2005, no. 2 (2005): 117–27. http://dx.doi.org/10.1155/ijrm.2005.117.

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An improved integral method is proposed and developed for the quantitative prediction of distorted inlet flow propagation through axial compressor. The novel integral method is formulated using more appropriate and practical airfoil characteristics, with less assumptions needed for derivation. The results indicate that the original integral method (Kim et al., 1996) underestimated the propagation of inlet flow distortion. The effects of inlet flow parameters on the propagation of inlet distortions as well as on the compressor performance and characteristic are simulated and analyzed. From the viewpoint of compressor efficiency, the propagation of inlet flow distortion is further described using a compressor critical performance and its associated critical characteristic. The results present a realistic physical insight to an axial-flow compressor behavior with a propagation of inlet distortion.

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Schmid, Norbert R., Dirk C. Leinhos, and Leonhard Fottner. "Steady Performance Measurements of a Turbofan Engine With Inlet Distortions Containing Co- and Counterrotating Swirl From an Intake Diffuser for Hypersonic Flight." Journal of Turbomachinery 123, no. 2 (2000): 379–85. http://dx.doi.org/10.1115/1.1343466.

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The influence of distorted inlet flow on the steady and unsteady performance of a turbofan engine, which is a component of an air-breathing combined propulsion system for a hypersonic transport aircraft, is reported in this paper. The performance and stability of this propulsion system depend on the behavior of the turbofan engine. The complex shape of the intake duct causes inhomogeneous flow at the engine inlet plane, where total pressure and swirl distortions are present. The S-bend intakes are installed axisymmetrically left and right into the hypersonic aircraft, generating axisymmetric mirror-inverted flow patterns. Since all turbo engines of the propulsion system have the same direction of rotation, one distortion corresponds to a corotating swirl at the low pressure compressor (LPC) inlet while the mirror-inverted image counterpart represents a counterrotating swirl. Therefore the influence of the distortions on the performance and stability of the ‘CO’ and ‘COUNTER’ rotating turbo engine are different. The distortions were generated separately by an appropriate simulator at the inlet plane of a LARZAC 04 engine. The results of low-frequency measurements at different engine planes yield the relative variations of thrust and specific fuel consumption and hence the steady engine performance. High-frequency measurements were used to investigate the different influence of CO and COUNTER inlet distortions on the development of LPC instabilities.

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Engeda, Abraham, Yunbae Kim, Ronald Aungier, and Gregory Direnzi. "The Inlet Flow Structure of a Centrifugal Compressor Stage and Its Influence on the Compressor Performance." Journal of Fluids Engineering 125, no. 5 (2003): 779–85. http://dx.doi.org/10.1115/1.1601255.

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The performance of centrifugal compressors can be seriously degraded by inlet flow distortions that result from an unsatisfactory inlet configuration. In this present work, the flow is numerically simulated and the flow details are analyzed and discussed in order to understand the performance behavior of the compressor exposed to different inlet configurations. In a previous work, complementary to this present work, experimental tests were carried out for the comparison of a centrifugal compressor stage performance with two different inlet configurations: one of which was a straight pipe with constant cross-sectional area and the other a 90-deg curved pipe with nozzle shape. The comparative test results indicated significant compressor stage performance difference between the two different inlet configurations. Steady-state compressor stage simulation including the impeller and diffuser with three different inlets has been carried out to investigate the influence of each inlet type on the compressor performance. The three different inlet systems included a proposed and improved inlet model. The flow from the bend inlet is not axisymmetric in the circumferential and radial distortion, thus the diffuser and the impeller are modeled with fully 360-deg passages.

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Tesis sobre el tema "Inlet distortions"

Guimaraes, Bucalo Tamara. "Fluid Dynamics of Inlet Swirl Distortions for Turbofan Engine Research." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82921.

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Significant effort in the current technological development of aircraft is aimed at improving engine efficiency, while reducing fuel burn, emissions, and noise levels. One way to achieve these is to better integrate airframe and propulsion system. Tighter integration, however, may also cause adverse effects to the flow entering the engines, such as total pressure, total temperature, and swirl distortions. Swirl distortions are angular non-uniformities in the flow that may alter the functioning of specific components of the turbomachinery systems. To investigate the physics involved in the ingestion of swirl, pre-determined swirl distortion profiles were generated through the StreamVane method in a low-speed wind tunnel and in a full-scale turbofan research engine. Stereoscopic particle image velocimetry (PIV) was used to collect three-component velocity fields at discrete planes downstream of the generation of the distortions with two main objectives in mind: identifying the physics behind the axial development of the distorted flow; and describing the generation of the distortion by the StreamVane and its impact to the flow as a distortion generating device. Analyses of the mean velocity, velocity gradients, and Reynolds stress tensor components in these flows provided significant insight into the driving physics. Comparisons between small-scale and full-scale results showed that swirl distortions are Mach number independent in the subsonic regime. Reynolds number independence was also verified for the studied cases. The mean secondary flow and flow angle profiles demonstrated that the axial development of swirl distortions is highly driven by two-dimensional vortex dynamics, when the flow is isolated from fan effects. As the engine fan is approached, the vortices are axially stretched and stabilized by the acceleration of the flow. The flow is highly turbulent immediately downstream of the StreamVane due to the presence of the device, but that vane-induced turbulence mixes with axial distance, so that the device effects are attenuated for distances greater than a diameter downstream, which is further confirmed by the turbulent length scales of the flow. These results provide valuable insight into the generation and development of swirl distortion for ground-testing environments, and establishes PIV as a robust tool for engine inlet investigations. Ph. D.

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Gong, Yifang 1964. "A computational model for rotating stall and inlet distortions in multistage compressors." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9733.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1999. "February 1999." Includes bibliographical references (p. 175-182). This thesis presents the conceptualization and development of a computational model for describing three-dimensional non-linear disturbances associated with instability and inlet distortion in multistage compressors. Specifically, the model is aimed at simulating the non-linear aspects of short wavelength stall inception, part span stall cells, and compressor response to three-dimensional inlet distortions. The computed results demonstrated the first-of-a-kind capability for simulating short wavelength stall inception in multistage compressors. The adequacy of the model is demonstrated by its application to reproduce the following phenomena: (1) response of a compressor to a square-wave total pressure inlet distortion; (2) behavior of long wavelength small amplitude disturbances in compressors; (3) short wavelength stall inception in a multistage compressor and the occurrence of rotating stall inception on the negatively sloped portion of the compressor characteristic; ( 4) progressive stalling behavior in the first stage in a mismatched multistage compressor; (5) change of stall inception type (from modal to spike and vice versa) due to IGV stagger angle variation, and "unique rotor tip incidences at these points where the compressor stalls through short wavelength disturbances. The model has been applied to determine the parametric dependence of instability inception behavior in terms of amplitude and spatial distribution of initial disturbance, and intra-blade-row gaps. It is found that reducing the inter-blade row gaps suppresses the growth of short wavelength disturbances. It is also concluded from these parametric investigations that each local component group (rotor and its two adjacent stators) has its own instability point (i.e. conditions at which disturbances are sustained) for short wavelength disturbances, with the instability point for the compressor set by the most unstable component group. For completeness, the methodology has been extended to describe finite amplitude disturbances in high-speed compressors. Results are presented for the response of a transonic compressor subjected to inlet distortions. by Yifang Gong. Ph.D.

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Eisemann, Kevin Michael. "A Computational Study of Compressor Inlet Boundary Conditions with Total Temperature Distortions." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35969.

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A three-dimensional CFD program was used to predict the flow field that would enter a downstream fan or compressor rotor under the influence of an upstream thermal distortion. Two distortion generation techniques were implemented in the model; (1) a thermal source and (2) a heated flow injection method. Results from the investigation indicate that both total pressure and velocity boundary conditions at the compressor face are made non-uniform by the upstream thermal distortion, while static pressure remains nearly constant. Total pressure at the compressor face was found to vary on the order of 10%, while velocity varies from 50-65%. Therefore, in modeling such flows, neither of these latter two boundary conditions can be assumed constant under these conditions. The computational model results for the two distortion generation techniques were compared to one another and evaluations of the physical practicality of the thermal distortion generation methods are presented. Both thermal distortion methods create total temperature distortion magnitudes at the compressor face that may affect rotor blade vibration. Both analyses show that holding static pressure constant is an appropriate boundary condition for flow modeling at the compressor inlet. The analyses indicate that in addition to the introduction of a thermal distortion, there is a potential to generate distortion in total pressure, Mach number, and velocity. Depending on the method of thermally distorting the inlet flow, the flow entering the compressor face may be significantly non-uniform. The compressor face boundary condition results are compared to the assumptions of a previous analysis (Kenyon et al., 2004) in which a 25 R total temperature distortion was applied to a computational fluid dynamics (CFD) model of a fan geometry to obtain unsteady blade pressure loading. Results from the present CFD analyses predict similar total temperature distortion magnitudes corresponding to the total temperature variation used in the Kenyon analyses. However, the results indicate that the total pressure and circumferential velocity boundary conditions assumed uniform in the Kenyon analyses could vary by the order of 2% in total pressure and approximately 8% in velocity distortion. This supports the previously stated finding that assuming a uniform total pressure profile at the compressor inlet may be an appropriate approximation with the presence of a weak thermal distortion, while assuming a constant circumferential velocity boundary condition is likely not sufficiently accurate for any thermal distortion. In this work, the referenced Kenyon investigation and others related to the investigation of distortion-induced aeromechanical effects in this compressor rotor have assumed no aerodynamic coupling between the duct flow and the rotor. A full computational model incorporating the interaction between the duct flow and the fan rotor would serve to alleviate the need for assuming boundary conditions at the compressor inlet. Master of Science

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Giuliani, James Edward. "Jet Engine Fan Response to Inlet Distortions Generated by Ingesting Boundary Layer Flow." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468564279.

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Lambie, David. "Inlet distortion and turbofan engines." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305300.

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Longley, John Peter. "Inlet distortion and compressor stability." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304354.

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Hoopes, Kevin M. "A New Method for Generating Swirl Inlet Distortion for Jet Engine Research." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49545.

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Jet engines operate by ingesting incoming air, adding momentum to it, and exhausting it through a nozzle to produce thrust. Because of their reliance on an inlet stream, jet engines are very sensitive to inlet flow nonuniformities. This makes the study of the effects of inlet nonuniformities essential to improving jet engine performance. Swirl distortion is the presence of flow angle nonuniformity in the inlet stream of a jet engine. Although several attempts have been made to accurately reproduce swirl distortion profiles in a testing environment, there has yet to be a proven method to do so. A new method capable of recreating any arbitrary swirl distortion profile is needed in order to expand the capabilities of inlet distortion testing. This will allow designers to explore how an engine would react to a particular engine airframe combination as well as methods for creating swirl distortion tolerant engines. The following material will present such a method as well as experimental validation of its effectiveness. Master of Science

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Dosne, Cyril. "Development and implementation of adjoint formulation of explicit body-force models for aero-propulsive optimizations." Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAX026.

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Dans le domaine de l’aéronautique civile, les études de plus en plus nombreuses portant sur les nouveaux systèmes moteurs, tels que les turbofans à très haut taux de dilution et les open-rotors, ainsi que sur les architectures d'intégration motrice innovantes, telles que la propulsion distribuée ou les systèmes à ingestion de couche limite, nécessitent une modélisation couplée de l’aérodynamique externe et du système propulsif, et ce dès les premiers stades de la conception. Les modèles body-force se sont avérés capables de reproduire fidèlement la majeure partie des phénomènes de couplage aéro-propulsif, comme la réponse aérodynamique du moteur aux distorsions d’entrée d’air, et ce à un coût de calcul réduit. Cependant, ils manquent d'une formulation adjointe pour être employés efficacement dans des optimisations par gradient. Cette thèse de doctorat se concentre sur le développement d'une approche adjointe pour les modèles body-force explicites. Tout d'abord, plusieurs optimisations aéro-propulsives sont menées sur une configuration académique de propulsion distribuée, à l'aide d'un modèle body-force réduit. Malgré la simplicité de ce modèle (d’intérêt pour les études de conception amont), une réduction de 10,5 % de la consommation de puissance est obtenue. Le potentiel de cette nouvelle méthodologie est ensuite évalué pour l'optimisation préliminaire de compresseurs, d'abord sans distorsion d’entrée d’air. Le modèle body-force de Hall est considéré pour cette étude. Les gradients de forme des aubes calculés à l’aide de l’adjoint body-force sont comparés à ceux obtenus via des simulations de haute-fidélité. Les résultats obtenus révèlent une très bonne capacité de prédiction des gradients du rotor par l’adjoint body-force, pour une grande partie de la caractéristique du compresseur, et particulièrement pour les points de fonctionnement situés entre le pompage et la zone de fonctionnement nominal du compresseur. En revanche, la précision de ces gradients est réduite à proximité du blocage. Pour le stator, seuls les effets liés à la désadaptation de l’aube au flux incident peuvent être captés. L’optimisation conduite avec l’adjoint body-force au point de fonctionnement nominal a permis d’améliorer le rendement du compresseur, ce qui a été confirmé par des simulations de haute-fidélité. Sous distorsion radiale, la méthode adjointe du body-force s’est à nouveau révélée capable d’améliorer les performances du compresseur en adaptant la géométrie des aubages aux perturbations d’entrée d’air. Les analyses haute-fidélité conduites sur les géométries obtenues par optimisations utilisant l’adjoint body-force montrent une augmentation du rendement isentropique comprise entre 1,16 et 1,47%, selon la formulation du problème d’optimisation retenue. Enfin, une optimisation du compresseur a été conduite à l’aide de l’adjoint body-force dans le cas d’une distorsion s’étendant sur la totalité de la circonférence de l’entrée d’air. Ces résultats sont très prometteurs et les observations effectuées sont cohérentes avec celles disponibles dans la communauté scientifique et obtenue à l’aide de calcul de haute-fidélité In civil aviation, the increasing exploration of innovative engine systems – such as ultra-high bypass ratio turbofan or open-rotor – and breakthrough engine-integration architectures – such as distributed propulsion or boundary-layer ingestion – require a coupled modeling of the aerodynamic and propulsion subsystems from the earliest design stages. Body-force models have proven capable of faithfully reproducing most of the coupling phenomena, such as the engine response to inlet flow distortions, at reduced computational cost. However, they lack an adjoint formulation to be efficiently used in gradient-based optimizations. The present PhD thesis focuses on the development of an adjoint approach for explicit body-force models. First, aero-propulsive optimizations of an academic distributed propulsion configuration are conducted using a lumped body-force model. Despite the simplicity of this model (of interest for conceptual design studies), 10.5% decrease in power consumption is achieved. Then the potential of this new methodology is investigated for the preliminary optimization of compressor stages, at first under clean inflow conditions. The Hall body-force model is considered for such purpose. The comparison of the blade shape gradients computed by the adjoint body-force with high-fidelity ones, obtained from blade-resolved computations, shows very good prediction for the rotor. This is observed over a large portion of the compressor characteristic, especially between near-design and surge operating conditions, while accuracy is reduced near the blockage. On the contrary, for stator shape gradients, only flow misalignment effects can be captured. At design conditions, the improvement of the compressor efficiency obtained by the adjoint body-force optimization has been confirmed through high-fidelity simulations. Optimization under radial inlet distortion are then investigated. Once again, the adjoint body-force approach is found capable of enhancing the compressor performances, by adapting its geometry to the off-design inflow conditions. According to high-fidelity analysis of the body-force optimized blade geometry, an increase in compressor isentropic efficiency between 1.16 and 1.47% is achieved, given the formulation of the optimization problem. Finally, an optimization of the compressor under full-annulus inlet distortion is conducted leading to very promising results, which are consistent with those found in the literature using advanced simulations

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Van, Schalkwyk Christiaan Mauritz. "Active control rotating stall with inlet distortion." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10827.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1996. Includes bibliographical references (p. 179-182). by Christiaan Mauritz Van Schalkwyk. Ph.D.

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Papamarkos, Ioannis. "Inlet distortion generation for a transonic compressor." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FPapamarkos.pdf.

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Más fuentes

Libros sobre el tema "Inlet distortions"

A, Ladd J., Yuhas A. J, and United States. National Aeronautics and Space Administration., eds. Dynamic inlet distortion prediction with a combined computational fluid dynamics and distortion synthesis approach. National Aeronautics and Space Administration, 1996.

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M, Greitzer Edward, and Lewis Research Center, eds. Final technical report on grant NAG3-1567 entitled Inlet distortion in engines on VSTOL aircraft. The Center, 1994.

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Yuhas, Andrew J. Design and development of an F/A-18 inlet distortion rake: a cost and time saving solution. Dryden Flight Research Center, 1995.

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United States. Army Aviation Research and Technology Activity. and United States. National Aeronautics and Space Administration., eds. Effects of inlet distortion on the development of secondary flows in a subsonic axial inlet compressor rotor. National Aeronautics and Space Administration, 1991.

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H, Anderson Bernhard, Shaw Robert J. 1946-, and United States. National Aeronautics and Space Administration., eds. A full Navier-Stokes analysis of subsonic diffuser of a a bifurcated 70/30 supersonic inlet for high speed civil transport application. National Aeronautics and Space Administration, 1994.

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D, Baust Henry, Agrell Johan, and NASA Glenn Research Center, eds. Management of total pressure recovery, distortion and high cycle fatigue in compact air vehicle inlets. National Aeronautics and Space Administration, Glenn Research Center, 2002.

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H, Anderson Bernhard, and United States. National Aeronautics and Space Administration., eds. A study on vortex flow control on inlet distortion in the re-engined 727-100 center inlet duct using computational fluid dynamics. National Aeronautics and Space Administration, 1992.

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1945-, Levy R., and United States. National Aeronautics and Space Administration., eds. A design strategy for the use of vortex generators to manage inlet-engine distortion using computational fluid dynamics. National Aeronautics and Space Administration, 1991.

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Center, Ames Research, ed. Sea level static calibration of a compact multimission aircraft propulsion simulator with inlet flow distortion. National Aeronautics and Space Administration, Ames Research Center, 1991.

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Más fuentes

Capítulos de libros sobre el tema "Inlet distortions"

Iseler, Jens, Andreas Lesser, and Reinhard Niehuis. "Numerical Investigation of a Transonic Axial Compressor Stage with Inlet Distortions." In High Performance Computing in Science and Engineering, Garching/Munich 2009. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-13872-0_16.

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Kurzke, Joachim, and Ian Halliwell. "Inlet Flow Distortion." In Propulsion and Power. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75979-1_6.

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Wartzek, Fabian, Felix Holzinger, Christoph Brandstetter, and Heinz-Peter Schiffer. "Realistic Inlet Distortion Patterns Interacting with a Transonic Compressor Stage." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-21127-5_17.

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Qu, Yaoyao, and Xiaoqing Qiang. "Design and Test of an Aero-Engine Inlet Distortion Screen Facility." In Lecture Notes in Electrical Engineering. Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-0651-2_12.

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Theune, Marius, Dirk Schönweitz, and Rainer Schnell. "Sensitivity of a Low Pressure Ratio Jet Engine Fan to Inlet Distortion." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-27279-5_6.

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Zhang, Bohan, Qiang Wang, Haiyang Hu, and Yahua Zhang. "The Simulation of Compressor Performance of Inlet Distortion Using Split Actuator Disk Model." In Lecture Notes in Electrical Engineering. Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3305-7_23.

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Lesser, Andreas, Sonja Schulze, Reinhard Niehuis, Christian Kähler, and Jan Lieser. "Analytical Design of an Inlet Distortion Generator and Its Experimental and Numerical Validation." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design. Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-35680-3_5.

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Li, Jun, Youtian Zhou, and Guoxing Song. "Experimental and Numerical Studies on Compressor Nonlinear Behaviors with Inlet Distortion and Their Interaction." In Nonlinear Systems and Complexity. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94301-1_6.

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Huang, J., H. Wu, and W. H. Du. "Experimental Investigation and Analysis of an Axial Compressor Stage with 45° Circumferential Inlet Flow Pressure Distortion." In New Trends in Fluid Mechanics Research. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75995-9_166.

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Actas de conferencias sobre el tema "Inlet distortions"

Defoe, J. J., and D. K. Hall. "Fan Performance Scaling With Inlet Distortions." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-58009.

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Applications such as boundary-layer-ingesting fans, and compressors in turboprop engines require continuous operation with distorted inflow. A low-speed axial fan with incompressible flow is studied in this paper. Previous work in the literature has shown that the same flow mechanisms contributing to the response of a fan to distortion are at play in incompressible and transonic flows. The objective is to determine how fan performance scales as the type and severity of inlet distortion varies at the design flow coefficient. A distributed source term approach to modeling the rotor and stator blade rows is used in numerical simulations in this paper. The approach has been shown to capture overall stage performance and flow field behavior with distortions having length scales much longer than the blade pitch. The approach requires only knowledge of the blade geometry, but the model does not include viscous losses. As a result, efficiency is not assessed but instead a metric based on changes in diffusion factor is defined which is conjectured to be related to efficiency changes. Distortions in stagnation pressure, swirl, and stagnation temperature are considered. By studying the distortions individually, it is found that the diffusion metric scales linearly with the intensity of the distortions (i.e. the ratio of minimum to maximum values) but that changes in distortion location relative to the fan axis produce nonlinear changes in the diffusion metric. Combinations of distortions are also studied and it is found that the diffusion metric associated with the combined distortion can be predicted using a summation procedure for the metrics associated with the individual constituent distortions. The mechanism found to govern the effectiveness of this summation procedure is the incidence distortions at rotor and stator inlet.

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Lesser, Andreas, and Reinhard Niehuis. "Transonic Axial Compressors With Total Pressure Inlet Flow Field Distortions." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26627.

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Non-uniform inlet flow has come back into focus of research during the last years due to the need of increasing the operational range of airborne engines. Higher climbing rates for lower noise pollution at airports as well as boundary layer ingesting inlet designs lead to the demand of inlet distortion resistant engines and compressors, in particular. To fulfill this design task, a deep understanding of the dominant flow physics of the distortion transport through the compressor as well as the influence of the compressor on the upstream flow field is needed. This paper starts with the transport of a circumferential total pressure distortion through a compressor stage. Using numerical results, previously validated by experimental data, a phenomenological approach for the transport is presented. The most important finding is the essential role of the different propagation speeds of the static pressure distortion and the inflow velocity distortion and its decoupling. A static pressure and an inflow velocity distortion are present for all kinds of total pressure distortions caused by the upstream flow field redistribution of the compressor. This decoupling causes not only a significant circumferential increase of the distorted sector but also a strong variation of the distortion magnitude downstream of the compressor stage. All relevant phenomena are present in the phenomenological approach as well as in the numerical and the referred experimental results. Inlet distortions result in a decrease of stability margin [1],[2]. The crucial area for the stability of most modern transonic compressors is the tip region; therefore, the tip region was under particular investigation. The numerical results show that the flow field in the distorted area is shifted toward the stall line. The shock system and the tip clearance vortex behave similar to the results near stall with uniform inflow. No local stall can be observed, although the local operating points within the distorted sector travel beyond the stall line of the compressor map with uniform inflow. Finally, a new analytical approach for the critical distortion angle is presented. The main finding is the circumferential extent has to be big enough to separate the zones of decoupled distortion quantities.

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Toracchio, Riccardo, Sina Stapelfeldt, Koen Hillewaert, and Fabrizio Fontaneto. "Forced Response Analysis of a Highly-Loaded Low-Pressure Compressor Stage With Inlet Distortions." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103881.

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Abstract Due to modern evolutions in propulsion, in view of obtaining higher propulsive efficiency, turbofan engines are subjected to ever higher inlet flow distortions. In these systems, structural damage can be induced by distortion patterns with excitation close to the blade natural frequency. To fill the gap currently present in literature about the impact of inlet distortions on the aeroelastic behaviour of engine components, this paper presents an aerodynamic damping and forced-response analysis on a highly-loaded axial compressor subjected to intake total pressure distortions. First, a stability analysis for the vibrational mode with natural frequency close to the resonance condition at the nominal speed of the machine is performed. Blade deformations are then computed through a distortion induced forced-response analysis at different distortion amplitudes. This work aims at studying the aeromechanical behaviour of a modern compressor, highlighting that the amplitude of the blade vibration does not increase linearly with the distortion amplitude.

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Fortin, J., and W. C. Moffatt. "Inlet Flow Distortion Effects on Rotating Stall." In ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-215.

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For many years there has been a significant effort to better understand rotating stall/surge phenomena in axial compressors, as well as the effects of inlet flow distortions. Most experimental investigations to date, whether on laboratory compressors or on full scale jet engines, have tended to focus separately on the effects of these two flow disturbances on compressor performance. The purpose of the present study was to experimentally assess the influence of inlet flow distortions on the inception and nature of rotating stall in a full scale engine compressor. This paper reports results obtained for the first stage rotor of a 10-stage compressor subjected to screen-induced inlet pressure distortions. Previous investigations had shown that during part-speed operation, the front stages operated in rotating stall, and hot-film probe measurements made during the present study showed that the presence of the distortion screens did not affect the speed of the rotating stall pattern, but in some instances changed the number of cells present. However, low frequency flow fluctuations characteristic of surge were much more prevalent when the screens were in place. Also, the further the sensing probe was displaced tangentially in the rotor rotation direction from the screens, the more intense the fluctuations, leading one to conclude that the screens had a localized damping effect on the surge cycle.

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Longley, J. P., H. W. Shin, R. E. Plumley, et al. "Effects of Rotating Inlet Distortion on Multisage Compressor Stability." In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-220.

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In multi-spool engines, rotating stall in an upstream compressor will impose a rotating distortion on the downstream compressor, thereby affecting its stability margin. In this paper experiments are described in which this effect was simulated by a rotating screen upstream of several multistage low-speed compressors. The measurements are complemented by, and compared with, a theoretical model of multistage compressor response to speed and direction of rotation of an inlet distortion. For co-rotating distortions (i.e., distortions rotating in the same direction as rotor rotation), experiments show that the compressors exhibited significant loss in stability margin and that they could be divided into two groups according to their response. The first group exhibited a single peak in stall margin degradation when the distortion speed corresponded to roughly 50% of rotor speed. The second group showed two peaks in stall margin degradation corresponding to distortion speeds of approximately 25–35% and 70–75% of rotor speed. These new results demonstrate that multistage compressors can have more than a single resonant response. Detailed measurements suggest that the two types of behavior are linked to differences between the stall inception processes observed for the two groups of compressors and that a direct connection thus exists between the observed forced response and the unsteady flow phenomena at stall onset. For counter-rotational distortions, all the compressors tested showed minimal loss of stability margin. The results imply that counter-rotation of the fan and core compressor, or LP and HP compressors, could be a worthwhile design choice. Calculations based on the two-dimensional theoretical model show excellent agreement for the compressors which had a single peak for stall margin degradation. We take this first-of-a-kind comparison as showing that the model, though simplified, captures the essential fluid dynamic features of the phenomena. Agreement is not good for compressors which had two peaks in the curve of stall margin shift versus distortion rotation speed. The discrepancy is attributed to the three-dimensional and short length scale nature of the stall inception process in these machines; this includes phenomena that have not yet been addressed in any model.

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Han, Fenghui, Jiajian Tan, Yijun Mao, Datong Qi, and Yiyun Zhang. "Effects of Flow Loss and Inlet Distortions Caused by Radial Inlet on the Performance of Centrifugal Compressor Stage." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-09693.

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Radial inlet is a typical upstream component in centrifugal compressors. Compared to axial inlet, radial inlet generates additional flow loss and introduces inlet distortions to the impeller inlet, which negatively impacts the performance of the whole centrifugal compressor. In this paper, two centrifugal compressor stages with different radial inlets were investigated with numerical simulations. Three computational models, (i) with radial inlet (ii) without flow loss and inlet distortions (iii) with flow loss but no inlet distortions, were built for each compressor stage, and calculations were carried out to analyze the respective effects of flow loss and inlet distortions caused by radial inlet on the performances of the compressor stage and the downstream components. The present study validates that flow loss and inlet distortions caused by radial inlet are the main factors by means of which the radial inlet affects the performance of the centrifugal compressor. What’s more, the results indicate that flow loss in radial inlet only affects the performance of the whole radial inlet stage, but has little effect on the downstream components such as the impeller; while inlet distortions caused by radial inlet not only negatively influence the performance of the whole radial inlet stage, but also have significant effects on the downstream components. This research, as a preliminary work of the improvement study, provides references for the structure modifications of radial inlet in the next stage.

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Sureshkumar, Prathiban, Kuen-Bae Lee, Ricardo Puente, and Sina Stapelfeldt. "Impact of the Spatial Arrangement of Inlet Distortions on Resonant Fan Response." In GPPS Chania22. GPPS, 2022. http://dx.doi.org/10.33737/gpps22-tc-132.

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Predicting the resonant forced response of aero-engine fans from inlet distortions in crosswind conditions is challenging, primarily due to the difficulty in correctly characterising and modelling the inlet distortion. To overcome this difficulty, an understanding of the distortion parameters which influence fan response is necessary. It is generally accepted that the amplitude of the total pressure distortion is an important factor. However, little is known about the importance of spatial arrangement of flow features in the intake. This paper hence presents a systematic study into the range of response levels resulting from different spatial arrangements of the distortion, using unsteady Reynolds-averaged Navier-Stokes simulations of a civil turbofan under crosswind conditions. The results show that the spatial arrangement of flow features in the intake, and thus inlet distortion, can lead to the generation of a large range of fan modal responses; co-location of nodal lines in the inlet distortion and mode shape appear to generate the worst responses. The results also suggest that the order in which intake flow features (i.e. the ground vortex and windward lip separation) interact with the fan can significantly alter the modal response, where this order of interaction could hypothetically be flipped by considering crosswinds in opposing directions, or when considering opposite handed fans. v

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Pazur, Wolfram, and Leonhard Fottner. "The Influence of Inlet Swirl Distortions on the Performance of a Jet Propulsion Two-Stage Axial Compressor." In ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-147.

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Aeroengine intakes containing S-shaped diffusers produce different types of inlet swirl distortions and essentially a combination of a twin swirl and a bulk swirl. The main object of this investigation was to assess the influence of inlet swirl distortions on the performance of a transonic two-stage axial compressor installed in a turbo jet bypass engine Larzac 04. A typical inlet swirl distortion was simulated by a delta-wing in front of the engine. An experimental method was investigated to measure the performance map of the installed low pressure compressor for different engine operating lines. The influence of an inlet swirl distortion with different strengths on the performance map of the compressor was investigated experimentally. It is shown that the performance parameters decrease and a temperature distortion is generated behind the compressor. As the basis of the theoretical investigations of the performance map including inlet swirl distortions a computing model considering four compressors working in parallel was established. The model is based on the idea that an inlet swirl distortion can be substituted by two fundamental types of swirl components, i.e. a bulk swirl co-rotating, and a bulk swirl counter-rotating to the revolution of the compressor. Computed performance maps of the compressor will be discussed and compared with the experimental data.

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Hah, Chunill, Douglas C. Rabe, Thomas J. Sullivan, and Aspi R. Wadia. "Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-547.

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The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

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Charalambous, Nikolaos, Tiziano Ghisu, Giuseppe Iurisci, Vassilios Pachidis, and Pericles Pilidis. "Axial Compressor Response to Inlet Flow Distortions by a CFD Analysis." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53846.

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The usual approach to compressor design considers uniform inlet flow characteristics. Especially in aircraft applications, the inlet flow is quite often non uniform, and this can result in severe performance degradation. The magnitude of this phenomenon is amplified in military engines due to the complexity of inlet duct configurations and the extreme flight conditions. CFD simulation is an innovative and powerful tool for studying inlet distortions and can bring this inside the very early phases of the design process. This project attempts to study the effects of inlet flow distortions in an axial flow compressor trying to minimize the use computer resources and computational time. The first stage of a low bypass ratio compressor has been analyzed and its clean and distorted performance compared outlining the principal changes due to uneven flow distribution: drop in mass flow, increase in pressure and temperature ratios, decrease in surge margin. Three different studies have then been conducted to better understand the effects of the level, the type and the frequency of the distortion.

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Informes sobre el tema "Inlet distortions"

Sedlock, Dennis. Improved Statistical Analysis Method for Prediction of Maximum Inlet Distortion. Defense Technical Information Center, 1985. http://dx.doi.org/10.21236/ada153767.

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Martinez, Melissa. Visual Patching and Imaging Chambers. ConductScience, 2022. http://dx.doi.org/10.55157/cs20220507.

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Specimens obtained from brain slicing experiments, cell research, and skin studies are sensitive to temperature variations, humidity, and air quality. Proper temperature control is crucial to prevent cell distortion and necrosis, ensuring accurate observations and data collection. A visual patching and imaging chamber is introduced as a vital tool for maintaining optimal specimen temperature in behavioral, neuroimaging, and electrophysiological studies. The chamber features an aluminum heat exchanger plate with precise temperature control, gas inlet, and perfusate tubes. It's used in rodent research for preserving tissue viability and collecting accurate data in various experiments.

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Davoudzadeh, F., N. S. Liu, S. J. Shamroth, and S. J. Thoren. A Navier-Stokes Study of Cascade Flow Fields Including Inlet Distortion and Rotating Stall. Defense Technical Information Center, 1987. http://dx.doi.org/10.21236/ada193109.

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Bidier, S., U. Khristenko, A. Kodakkal, C. Soriano, and R. Rossi. D7.4 Final report on Stochastic Optimization results. Scipedia, 2022. http://dx.doi.org/10.23967/exaqute.2022.3.02.

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This deliverable report focuses on the final stochastic optimization results obtained within the EXAscale Quantification of Uncertainties for Technology and Science Simulation (ExaQUte) project. Details on a novel wind inlet generator that is able to incorporate local wind-field data through a deep-learned rapid distortion model and generates the turbulent wind data during run-time is presented in section 2. Section 3 presents the results of the overall stochastic optimization procedure applied to a twisted tapered tower with multiple design parameters within an uncertain synthetic wind field. Thereby, the significance of the developed methods and the obtained results are discussed and their integration in industrial wind-engineering workflows is outlined in section 4.

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