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 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.

Numerical analysis on the conceptual design of an air-breathing engine inlet working in mach number 3∼5.5

2021 ◽  
pp. 095441002110113
Author(s):  
Chao Huo ◽  
Zhenhua Yang ◽  
Zhengze Zhang ◽  
Peijin Liu
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Back Pressure ◽  
Pressure Recovery ◽  
Shock Train ◽  
Recovery Coefficient ◽  
Air Breathing ◽  
Supersonic Inlet ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient

Based on the equal-intensity shock theory, this article designed a supersonic inlet working in Mach number 3.0∼5.5 with the background of an air-breathing engine. The inlet applied the four-shock train mixed compression configuration and inserted a sidewall compression at the beginning of the isolator. Through developing effective 3D RANS computations validated by current experiments, the performance of the designed inlet was identified. The designed inlet self-starts at freestream Mach number Ma∞ = 3.0 under which the total pressure recovery coefficient has dramatic increment, and the aerodynamic choking at the inlet throat no longer presents; the inlet keeps working at all studied flight states with zero angle of attack (AoA) and achieves shock-on-lip at the design point Ma∞ = 5.0. Both positive and negative AoAs can disrupt the equal-intensity shock allocations, which degrade the inlet performance. The inlet obtains maximum total pressure recovery coefficient at zero AoA. The maximum back pressure at Ma∞ = 3.0∼5.5 obtained by the inlet surpasses the requirements and keeps a certain margin. The inlet performance basically meets all the goals proposed by the engine.

scholarly journals A Simple Theory and Performance Prediction for a Shrouded Wind Turbine with a Brimmed Diffuser

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3661
Author(s):  
Koichi Watanabe ◽  
Yuji Ohya
Keyword(s):  
Wind Turbine ◽  
Pressure Coefficient ◽  
Back Pressure ◽  
Simple Theory ◽  
Broad Ring ◽  
Recovery Coefficient ◽  
Wind Turbine System ◽  
And Performance ◽  
Pressure Recovery Coefficient ◽  
Good Agreement

We developed a new wind turbine system that consists of a diffuser shroud with a broad-ring brim at the exit periphery and a wind turbine inside it. The shrouded wind turbine with a brimmed diffuser, which we called a “wind lens turbine” (WLT), has demonstrated power augmentation by a factor of about 2–5 compared with a bare wind turbine for a given turbine diameter and wind speed. The increase in power output depends on the diffuser shape and length and the brim height. However, a simple theory presented in this paper argues that only two performance coefficients are needed to predict the performance of WLT. The coefficients are the back pressure coefficient of the brim and the pressure recovery coefficient of the diffuser. We theoretically showed that the back pressure coefficient was particularly important for the performance of WLT. Finally, the simple theory was evaluated with experimental results. The results showed good agreement with each other.

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.

Numerical Study on the Plasma Generated by Different Discharge Modes at the Upstream of Fuel Jet in Scramjet Combustor

2013 ◽  
Vol 444-445 ◽  
pp. 1345-1349
Author(s):  
Si Yin Zhou ◽  
Wan Sheng Nie ◽  
Bo He ◽  
Xue Ke Che ◽  
Xue Min Tian
Keyword(s):  
Total Pressure ◽  
Recirculation Zone ◽  
Pressure Recovery ◽  
Flow Conditions ◽  
Recovery Coefficient ◽  
Discharge Mode ◽  
Scramjet Combustor ◽  
Fuel Jet ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient

How to enhance the combustion and reduce the total pressure loss in scramjet combustor are very critical for the practical application of hypersonic aircraft. Based on the dominant thermal mechanism of arc plasma, the plasma generated in combustor is regarded as a promising method to improve the combustion. As a result, the combustor model with transverse fuel jet and plasma generated by two discharge modes at the upstream of flameholding cavity is established and it is used to study the mechanism of fuel mixing enhancement through numerical investigation. The results show that an oblique shock wave would be formed at the upstream of the pseudo small plasma hump, and interact with the separation shock wave induced by the transverse jet. This results in the recirculation zone at the upstream of fuel jet being enlarged obviously. Besides that, under the non-reaction flow conditions, the total pressure recovery coefficient increases due to the plasma generated. However, the total pressure recovery coefficient varies apparently and the shear layer above the cavity is fluctuant when the plasma is generated by periodical discharge mode. While under the reaction flow conditions, the shear layer develops thicker and the total pressure recovery coefficient decreases. And due to the existing of plasma, the mole fraction of product water increases. But compared with the steady discharge mode, the level of water is lower and the total pressure recovery coefficient decreases more under the periodical discharge mode. Though the plasma generated by steady discharge mode shows better performance in assisting combustion and reducing the pressure loss, considering the energy saving and the use of different parameters of the periodical discharge, the same effects of enhancing the fuel mixing through enlarging the recirculation zone located at the upstream of fuel jet and promoting the mass exchange of cavity can be reached. More numerical experiments have to be done to optimize the parameters of periodical discharge plasma to receive a best improvement on the performance of scramjet combustor.

Effects of boundary-layers bleeding on unstart/restart characteristics of hypersonic inlets

2009 ◽  
Vol 113 (1143) ◽  
pp. 319-327 ◽  
Author(s):  
J. Chang ◽  
D. Yu ◽  
W. Bao ◽  
Y. Fan ◽  
Y. Shen
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Boundary Layers ◽  
Total Pressure ◽  
Performance Parameter ◽  
Recovery Coefficient ◽  
Hypersonic Inlet ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient ◽  
Hypersonic Inlets

Abstract A series of mixed-compression hypersonic inlets at different bleeding rates were simulated at different freestream conditions in this paper. The unstart/restart characteristics of hypersonic inlets were analysed and the reasons why the unstart/restart phenomenon is in existence is presented. The unstart/restart characteristics of hypersonic inlets at different bleeding rates were given. The effects of boundary-layer bleeding on the performance parameter (mass-captured coefficient, total-pressure recovery coefficient), starting and restarting Mach number of hypersonic inlets were discussed. In conclusion, boundary-layer bleeding can improve the performance parameter of hypersonic inlets, and can reduce the starting and restarting Mach number, and can broad the operation range of the hypersonic inlet.

Influence of Area Distribution With Fixed Trajectory on Serpentine Intake Duct Performance

2012 ◽  
Author(s):  
Ritesh Gaur ◽  
Vimala Narayanan ◽  
S. Kishore Kumar
Keyword(s):  
Total Pressure ◽  
Pressure Recovery ◽  
Maximum Pressure ◽  
Recovery Coefficient ◽  
Cross Sectional ◽  
Fixed Boundary ◽  
Area Distribution ◽  
Pressure Recovery Factor ◽  
Minimum Distortion ◽  
Pressure Recovery Coefficient

Performance of intake duct with fixed inlet trajectory and different area distributions have been analyzed using a commercial CFD (Computational Fluid Dynamics) software. The performance have been evaluated for fixed boundary conditions. The area distributions studied are defined by varying cross sectional area at different locations of intake duct by keeping the inlet and exit area same. The performance of the intake ducts are studied in terms of the pressure recovery coefficient, total pressure loss, pressure recovery factor and distortion coefficient in the present work. The motion caused by the change in centerline curvature is analyzed. The objective of the work is to derive a shape of the duct with minimum distortion of the flow and maximum pressure recovery.

Experimental and numerical investigation of a supersonic inlet with double S-bend diffuser

2021 ◽  
pp. 095441002098398
Author(s):  
Jinsheng Zhang ◽  
Huacheng Yuan ◽  
Yunfei Wang ◽  
Guoping Huang
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Aerodynamic Performance ◽  
Shock Train ◽  
Recovery Coefficient ◽  
Low Mach Number ◽  
Supersonic Inlet ◽  
Total Pressure Recovery ◽  
High Mach ◽  
Pressure Recovery Coefficient

Design of a supersonic inlet with double S-bend diffuser was developed. Numerical simulation and wind tunnel experiment were carried out to investigate the aerodynamic performance and variable geometric rules of the inlet. The result indicates that the variable geometry scheme adopted solves the contradiction between starting performance at low Mach number and aerodynamic performance at high Mach number. The inlet works normally and stably over a wide speed range. At design point, the total pressure recovery coefficient reaches 0.47. In addition, two different kinds of inlets with double S-bend diffuser and single S-bend diffuser were studied. Compared with the double S-bend diffuser, the total pressure recovery coefficient of the single S-bend diffuser is higher at low Mach number (Ma0 < 3) and lower at high Mach number (Ma0 > 3). With the increase of backpressure, shock train mainly moves upstream along the low-energy flow region in the diffuser. For the double S-bend diffuser, shock train will first move along the lower corner and then along the upper corner. For the single S-bend diffuser, it will only move along the upper corner. The strong secondary flow of the double S-bend is the main reason for the above phenomenon.

Aerodynamic Design Investigation on Inlet-Exhaust System Using Super-Ellipse Method

2012 ◽  
Vol 246-247 ◽  
pp. 446-450
Author(s):  
Yue Feng Li ◽  
Qing Zhen Yang ◽  
Xue Jiao Deng
Keyword(s):  
Cross Section ◽  
Total Pressure ◽  
Exhaust System ◽  
Shape Index ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Thrust Coefficient ◽  
Ellipse Method ◽  
Total Pressure Recovery ◽  
Pressure Recovery Coefficient

Generally, the shape index n is selected in a form when design the inlet-exhaust system using traditional super-ellipse method. Unfortunately, this selection process is time-consuming and not precise enough, so the cross-section designed by super-ellipse method may get distortions easily, which influences the inner flow and the total pressure of the inlet-exhaust system greatly. Associating the shape index n with the variation pattern of the inlet-exhaust cross-section, an improved super-ellipse method is developed to design the inlet-exhaust system. This method ensures the precision and uniqueness of shape index n for any cross-section in an adaptive way. The numerical simulation results show that the S-shape inlet designed using this method has high total pressure recovery coefficient and lower distortion coefficient, the S-shaped nozzle has high total pressure recovery coefficient and thrust coefficient.

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