scholarly journals Study on Three-Dimensional Inner Flow Field Characteristics and Performance of Scramjet

2019 ◽  
Vol 288 ◽  
pp. 02007
Author(s):  
Feng Gao ◽  
Jie Zhao ◽  
Cheng Tao Zhang
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Total Pressure ◽  
Static Pressure ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Recovery Coefficient ◽  
Inlet Flow ◽  
And Performance ◽  
Pressure Recovery Coefficient

The three-dimensional characteristics and performance of the flow field in the inlet of the scramjet engine were numerically simulated by CFD software. The flow characteristics in the width direction of the inlet and the influence of the aspect ratio on the performance of the inlet were studied. The calculation results show that the inlet flow has obvious three-dimensional characteristics, and the flow field structure is different in the width direction from the middle symmetrical section to the side wall surface, the Mach number is smaller and smaller, the static pressure is lower and lower, and the static temperature is higher, the greater the total pressure. The aspect ratio has little effect on the Mach number and static temperature of the outlet section of the inlet, but it has a great influence on the static pressure and total pressure. Within a reasonable range, the aspect ratio is doubled, the static pressure is increased by about 40%, and the total pressure is increased by about 84%. The inlet flow coefficient and the total pressure recovery coefficient increase as the aspect ratio increases. Within a reasonable range, the aspect ratio is doubled, the inlet flow coefficient is increased by approximately 53%, and the total pressure recovery coefficient is increased by approximately 83%.

Effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers

2003 ◽  
Vol 217 (1) ◽  
pp. 29-41 ◽  
Author(s):  
R B Anand ◽  
L Rai ◽  
S N Singh
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Area Ratio ◽  
Secondary Flows ◽  
Performance Characteristics ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Turning Angle ◽  
And Performance ◽  
Pressure Recovery Coefficient

The effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers (length-inlet diameter ratio, L/Di = 11:4) having an area ratio of 1.9 and centre-line length of 600 mm has been established. The experiments are carried out for three S-shaped circular diffusers having angles of turn of 15°/15°, 22.5°/22.5° and 30°/30°. Velocity, static pressure and total pressure distributions at different planes along the length of the diffusers are measured using a five-hole impact probe. The turbulence intensity distribution at the same planes is also measured using a normal hot-wire probe. The static pressure recovery coefficients for 15°/15°, 22.5°/22.5° and 30°/30° diffusers are evaluated as 0.45, 0.40 and 0.35 respectively, whereas the ideal static pressure recovery coefficient is 0.72. The low performance is attributed to the generation of secondary flows due to geometrical curvature and additional losses as a result of the high surface roughness (~0.5 mm) of the diffusers. The pressure recovery coefficient of these circular test diffusers is comparatively lower than that of an S-shaped rectangular diffuser of nearly the same area ratio, even with a larger turning angle (90°/90°), i.e. 0.53. The total pressure loss coefficient for all the diffusers is nearly the same and seems to be independent of the angle of turn. The flow distribution is more uniform at the exit for the higher angle of turn diffusers.

scholarly journals Numerical Study on Internal flow Field Dynamic Performance of Scramjet

2019 ◽  
Vol 288 ◽  
pp. 02009
Author(s):  
Feng Gao ◽  
Jie Zhao ◽  
Feng Li Chen
Keyword(s):  
Total Pressure ◽  
Pressure Pulsation ◽  
Dynamic Performance ◽  
Great Influence ◽  
Back Pressure ◽  
Flow Coefficient ◽  
Intake Port ◽  
Recovery Coefficient ◽  
And Performance ◽  
Pressure Recovery Coefficient

The pressure pulsation caused by the combustion of the combustion chamber of the scramjet engine has a great influence on the flow and performance of the inlet. Although the isolation section prevents the propagation of this pressure pulsation, the pressure pulsation still flows to the inlet flow field. And performance has an adverse effect. In this paper, a method for calculating the dynamic performance parameters of the inlet is discussed. The influence of the pulsating pressure of the combustion chamber on the performance of the inlet is preliminarily studied. The influence law of different forms of back pressure pulsation on the flow coefficient and the total pressure recovery coefficient is obtained. Different back pressure pulsation forms have a great influence on the flow coefficient. The faster the response, the more obvious the change of the flow coefficient. The larger the reduction, the more likely the inlet channel will not start. Different back pressure pulsations have little effect on the total pressure recovery coefficient. In the design of the intake port, the influence of the back pressure pulsation on the performance of the intake port should be fully taken into consideration, and measures should be taken to prevent the performance of the intake port from being affected by the back pressure pulsation.

scholarly journals Influence of Propeller Slipstream on the Flow Field of S-Shaped Intake

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shuili Ren ◽  
Peiqing Liu
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Engine Performance ◽  
Pressure Recovery ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Recovery Coefficient ◽  
Distortion Coefficient ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient

For turboprop engine, the S-shaped intake affects the engine performance and the propeller is not far in front of the inlet of the S-shaped intake, so the slipstream inevitably affects the flow field in the S-shaped intake and the engine performance. Here, an S-shaped intake with/without propeller is studied by solving Reynolds-averaged Navier-Stokes equation employed SST k-ω turbulence model. The results are presented as time-averaged results and transient results. By comparing the flow field in S-shaped intake with/without propeller, the transient results show that total pressure recovery coefficient and distortion coefficient on the AIP section vary periodically with time. The time-averaged results show that the influence of propeller slipstream on the performance of S-shaped intake is mainly circumferential interference and streamwise interference. Circumferential interference mainly affects the secondary flow in the S-shaped intake and then affects the airflow uniformity; the streamwise interference mainly affects the streamwise flow separation in the S-shaped intake and then affects the total pressure recovery. The total pressure recovery coefficient on the AIP section for the S-shaped intake with propeller is 1%-2.5% higher than that for S-shaped intake without propeller, and the total pressure distortion coefficient on the AIP section for the S-shaped intake with propeller is 1%-12% higher than that for the S-shaped intake without propeller. However, compared with the free stream flow velocity ( Ma = 0.527 ), the influence of the propeller slipstream belongs to the category of small disturbance, which is acceptable for engineering applications.

Aerodynamic Optimization Design of Exhaust Hood Diffuser for Steam Turbine With Three-Dimensional Reynolds-Averaged Navier-Stokes Solutions

2014 ◽  
Author(s):  
Jiandao Yang ◽  
Taowen Chen ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Optimization Design ◽  
Static Pressure ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Exhaust Hood ◽  
Aerodynamic Optimization ◽  
Recovery Coefficient ◽  
Last Stage ◽  
Pressure Recovery Coefficient

Combined with three-dimensional parameterization method of exhaust diffuser profile, aerodynamic performance evaluation method, response surface approximation evaluation model and Hooke-Jeeves direct search approach, aerodynamic optimization design of exhaust hood diffuser for steam turbine is presented. The aerodynamic performance of exhaust hood design candidate is evaluated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solutions. Aerodynamic optimization design of exhaust hood is conducted for the maximum of the static pressure recovery coefficient of exhaust hood. The design variables are specified by the exhaust diffuser profile parameterization method. The aerodynamic performance of the optimized exhaust hood and referenced design is numerically calibrated with consideration of the full last stage and rotor tip clearance. The static pressure recovery coefficient of the optimized exhaust hood is higher than that of the referenced design with consideration of the upstream last stage influence. Furthermore, the detailed flow pattern of the optimized exhaust hood and referenced design is also analyzed and compared.

Entrance Aspect Ratio Effect on S-Duct Inlet Performance at High-Subsonic Flow

2016 ◽  
Author(s):  
Asad Asghar ◽  
Robert A. Stowe ◽  
William D. E. Allan ◽  
Derrick Alexander
Keyword(s):  
Aspect Ratio ◽  
Total Pressure ◽  
Static Pressure ◽  
Three Dimensional ◽  
Area Ratio ◽  
Pressure Recovery ◽  
Exit Plane ◽  
Clear Trend ◽  
Parametric Investigation ◽  
Aspect Ratios

This paper reports the internal performance evaluation of S-duct diffusers with different entrance aspect ratios as part of an ongoing parametric investigation of a generic S-duct inlet. The generic S-duct diffusers were a rectangular-entrance (aspect ratio 1.5 and 2.0) transitioning S-duct diffuser in high subsonic (Mach number > 0.8) flow. The test section was manufactured using rapid prototyping for facilitating the parametric investigation of the geometry. Streamwise static pressure and exit-plane total pressure were measured in a test-rig using surface pressure taps and a 5-probe rotating rake, respectively and the baseline and a variant was simulated through computational fluid dynamics. The investigation indicated the presence of streamwise and circumferential pressure gradients leading to a three dimensional flow in the S-duct diffuser and distortion at the exit plane. The static pressure recovery increased for the diffuser with higher aspect ratio. Total pressure losses and circumferential and radial distortions at the exit plane were higher than that of the podded nacelle type of inlet. The increase in the total pressure recovery was observed for the increase in the aspect ratio for the baseline area ratio (1.57) S-ducts, but without a clear trend for the other area ratio (1.8) ducts. The work represents the beginning of the development of a database for the performance of a particular type of generic inlet. This database will be useful for predicting the performance of aero-engines and air vehicles in high subsonic flight.

CFD Analysis of a Centrifugal Compressor Impeller and Volute

1999 ◽  
Author(s):  
Harri Pitkänen ◽  
Hannu Esa ◽  
Petri Sallinen ◽  
Jaakko Larjola
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Prediction Method ◽  
Navier Stokes ◽  
Recovery Coefficient ◽  
Compressor Impeller ◽  
Compressor Performance ◽  
Pressure Recovery Coefficient

In this study, centrifugal compressor performance was predicted using CFD. Three-dimensional time-averaged impeller and volute simulations were performed using a Navier–Stokes code. The presented performance prediction method has been divided into three phases. Firstly, the impeller was calculated with a vaneless diffuser. That gives inlet boundary conditions for the volute analysis and the pressure ratio at the diffuser exit. Next, the volute analysis was performed and a static pressure recovery coefficient obtained. Finally, that result was combined with the pressure ratio prediction from the impeller analysis, and the overall compressor performance thus obtained.

Effects of Inlet Pressure Distortion on the Performance and Flow Field of a Centrifugal Compressor at Off-Design Conditions

2012 ◽  
Author(s):  
N. Sitaram ◽  
M. Govardhan ◽  
K. V. Murali
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Static Pressure ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Performance Measurements ◽  
Perforated Sheet ◽  
Sector Angle

The present paper presents experimental results on the effects of inlet total pressure distortion on the performance and flow field of a centrifugal compressor. The total pressure at inlet is artificially distorted by means of a perforated sheet, which is supported by a support mesh. A total of eleven configurations, including clean inlet configuration, are tested. Performance measurements and impeller inlet and exit flow studies at three flow coefficients, one near design flow coefficient, one below design flow coefficient and one above design flow coefficient, are carried out. The present paper presents and discusses results at off-design flow coefficients and the effects of stage loading on the distortion effects are presented. A new parameter, Distortion Index (DI) is introduced. As DI increases, the mass averaged total pressure at exit stations decreases. Distortion sector angle of 60° having the lowest total pressure is found to be the critical sector for circumferential distortion configurations. As the Distortion Correlation parameter, DC(60) increases, the mass averaged total pressure for circumferential distortion configuration decreases, except in the case of low flow coefficient where DC(60) is nearly constant. DC(60) also increases with sector angle. The static pressure normalized with static pressure for clean inlet decreases as the distortion sector angle is increased. Distortion attenuates the static pressure as the flow passes through the vaneless diffuser. The attenuation increases with the distortion sector angle.

Entrance Aspect Ratio Effect on S-Duct Inlet Performance at High-Subsonic Flow

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Asad Asghar ◽  
Robert A. Stowe ◽  
William D. E. Allan ◽  
Derrick Alexander
Keyword(s):  
Aspect Ratio ◽  
Total Pressure ◽  
Static Pressure ◽  
Three Dimensional ◽  
Area Ratio ◽  
Pressure Recovery ◽  
Exit Plane ◽  
Clear Trend ◽  
Parametric Investigation ◽  
Aspect Ratios

This paper reports the internal performance evaluation of S-duct diffusers with different entrance aspect ratios as part of a parametric investigation of a generic S-duct inlet. The generic S-duct diffusers studied had a rectangular entrance (aspect ratios of 1.5 and 2.0) transitioning S-duct diffuser in high-subsonic (Mach number > 0.8) flow. The test section was manufactured using rapid prototyping to facilitate the parametric investigation of the geometry. Streamwise static pressure and exit-plane total pressure were measured in a test-rig using surface pressure taps and a five-probe rotating rake, respectively. The baseline and a variant were simulated through computational fluid dynamics (CFD). The investigation indicated the presence of streamwise and circumferential pressure gradients leading to a three-dimensional flow in the S-duct diffuser and to distortion at the exit plane. The static pressure recovery increased for the diffuser with the higher aspect ratio. Total pressure losses and circumferential and radial distortions at the exit plane were higher than that of the podded nacelle type of inlet. An increase in the total pressure recovery was observed for the increase in the aspect ratio for the baseline area ratio (1.57) S-ducts, but without a clear trend for the other area ratio (1.8) ducts. The work represents the development of a database on the performance of a particular type of generic inlet. This database will be useful for predicting the performance of aero-engines and air vehicles in high-subsonic flight.

Transonic Axial Compressors With Total Pressure Inlet Flow Field Distortions

2014 ◽  
Author(s):  
Andreas Lesser ◽  
Reinhard Niehuis
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Static Pressure ◽  
Phenomenological Approach ◽  
Numerical Results ◽  
Tip Clearance ◽  
Compressor Stage ◽  
Inlet Flow ◽  
Inflow Velocity ◽  
Upstream Flow

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.

Experimental Study of Flow in a High Aspect Ratio 90 Deg Curved Diffuser

1998 ◽  
Vol 120 (1) ◽  
pp. 83-89 ◽  
Author(s):  
B. Majumdar ◽  
Ratan Mohan ◽  
S. N. Singh ◽  
D. P. Agrawal
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Static Pressure ◽  
Pressure Probe ◽  
Hot Wire ◽  
Recovery Coefficient ◽  
Wire Probe ◽  
Concave Wall ◽  
Vortical Motion ◽  
Pressure Recovery Coefficient

Measurements for developing turbulent flow in a high aspect ratio (AS = 6), small area ratio (AR = 2), 90 deg curved diffuser have been made. Mean velocities, static and total pressures, and turbulence intensities were measured using a three-hole pressure probe and a hot-wire probe. Flow visualization studies were also made using a tuft probe. Experiments show that, except for a very small zone near the exit, there is no flow reversal in any part of the diffuser. Streamwise bulk flow is seen to shift toward the concave wall side in the downstream half of the diffuser, under the influence of centrifugal force. One pair of counter-rotating vortical motion was identified at 30 deg turn, which break into more pairs (at least two) of counter-rotating vortices in the downstream. The z-plane velocity profiles show a nearly 2-D flow in the initial part of the diffuser but subsequently the flow becomes increasingly 3-D. A static pressure recovery coefficient of 51 percent was achieved.

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