Numerical Study on the Performance of Scramjet Isolator

Ruoyu Deng,Heuy Dong Kim 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

As one of the most promising propulsive systems in the future, the scramjet engine has drawn the attention of many researches. Detailed flow features concerned with the isolator play an important role in the scramjet system. The 2D numerical method has been used for the inlet-isolator with wind tunnel. In order to validate the ability of the numerical model, numerical results are compared with the experimental results. Overall pressure distributions show quite good match with the experimental results. Different back pressures have been researched for maximum pressure rising. According to the results, pressure profiles of inlet section are exactly the same in different back pressures, and the shock train is pushed toward the isolator entrance as the back pressure increases. The maximum back pressure without inlet unstart goes up rapidly and then keep constant when the isolator length increases. The optimal isolator length (L/Hth) is 8.7 in this model.

A Computational Study on the Supersonic Flow Characteristics in a Pintle Nozzle

Ruoyu Deng,Heuy-Dong Kim(김희동) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

Typical solid rocket motors (SRM) have advantage of their inherent simplicity and reliability, but they do not have the capability to change thrust profile like other propulsion system. Pintle technology is one of the means to achieve variable and programmable thrust. Dynamic characteristics of a pintle nozzle were studied numerically based on dynamic characteristics of pintle nozzle. A two-dimensional axisymmetric numerical simulation has been carried for thrust performance during the pintle moving process. To validate the ability of the numerical model, numerical results were compared with the experiment results. The chamber pressure distribution shows quite good match with the experimental result. Aiming to optimum dynamic performance, different pintle speeds should be researched. The period of chamber pressure and thrust variation becomes longer when the pintle speed decreases. There is a delay between of thrust variation and pintle movement. The result will provide the reference to the further development of shock vector control.

A Study on the Thrust Vector Control Using a By-Pass Flow Passage

Ruoyu Deng,National University 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5

Transverse gas injection into the supersonic stream has long been applied to many aerospace engineering applications such as combustion in scramjet engines and thrust control of supersonic vehicle jets. Detailed flow features concerned with the secondary gas injection play an important role in the fluidic thrust vectoring system. The 2D grid is built on the rocket nozzle with chamber bleed gas injection. In order to validate the ability of the numerical model, numerical results are compared with the experimental results. Overall pressure distributions show quite good match with the experimental results. For optimum vectoring effect, different expanded ratios should be researched. Significant change of system thrust ratio and specific impulse takes place in the overexpanded condition. It is indicated the secondary flow produces great effects for overexpanded conditions. The separation point of boundary layer moves upstream with increasing of secondary mass flow rate. System thrust ratio and specific impulse go down with increasing secondary mass flow. The result will provide the reference to the further development of shock vector control.

Numerical simulation of fluidic thrust vectoring in an axisymmetric supersonic nozzle

Ruoyu Deng,Fanshi Kong,김희동 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

Transverse secondary gas injection into an axisymmetric supersonic nozzle under standard atmosphere pressure is investigated to getthe performance of thrust vectoring control. An analytical model was established based on the transverse injection flow. ThreedimensionalCFD methods were performed with different transverse secondary injection models. To validate the ability of the numericalmodel, numerical results were compared with the analytical and experimental results. Overall pressure distributions show quite goodmatch with the analytical and experimental results. The Mach number contours in different injection positions were obtained. Reflectionof the bow shock occurred for xj/L = 0.6, not for xj/L = 0.9. Nozzle pressure ratio is also the key factor for shock vector control. Based onthis data, thrust vectoring efficiency and system thrust ratio have been considered. Finally, the pressure distributions in different momentumflux ratios were studied in CFD and analytical models. The separating point of boundary layer is moving upstream with the increasingof momentum flux ratio. The result will provide the reference to the further development of shock vector control.

Numerical Visualization of the Pseudo-Shock Waves using LES

Ruoyu Deng,Yingzi Jin,Heuy Dong Kim(김희동) 한국가시화정보학회 2015 한국가시화정보학회지 Vol.13 No.3

The interaction between a normal shock wave and a boundary layer along a wall surface in internal compressible flows causes a very complicated flow. This interaction region containing shock train and mixing region is called as pseudo-shock waves. Pseudo-shock waves in the divergent part of a rectangular nozzle have been investigated by using large-eddy simulation (LES). LES studies have been done for the complex flow phenomena of three-dimensional pseudo-shock waves. The LES results have been validated against experimental wall-pressure measurements. The LES results are in good agreement with experimental results. Pseudo-shock length and corner separation have been studied in three-dimensional LES model. Comparison of centerline pressure measurement and 3D visualization measurement has been discussed for the corner separation position. It has been concluded that the pseudo-shock length should be measured by using 3D visualization measurement.

Effects of isolator length on pseudoshock wave in a rectangular duct

Ruoyu Deng,Ke Xin Wu,Heuy Dong Kim,Qijun Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

The scramjet isolator length is a very important influence factor on the stability of scramjet engines. The effects of the isolator length on the pseudo-shock wave (PSW) were studied through a numerical method. The steady and unsteady PSW characteristics were analyzed to explore the influence mechanism of the isolator length. The numerical model was validated with the existing experimental results, and the validation results show that the numerical model has high accuracy. The effects of the structural variation of the PSW on self-excited oscillation were explored at different isolator lengths. Result shows that increasing the isolator length increases the length of the PSW. The leading shock becomes stable with the increasing of PSW length, and the following shocks become unstable. This phenomenon indicates that the unsteady characteristics of self-excited oscillation are closely related to the PSW structure. The influence mechanism of isolator length is represented by the amplitude difference of the leading and following shocks caused by the PSW structure variation.

Numerical Visualization of the Pseudo-Shock Waves using LES

Ruoyu Deng,Heuy Dong Kim 한국가시화정보학회 2015 한국가시화정보학회 학술발표대회 논문집 Vol.2015 No.12

Pseudo-shock waves in the divergent part of a Laval nozzle with rectangular cross section have been investigated through numerical methods using large-eddy simulation (LES). LES studies have been done for the complex flow phenomena of three-dimensional pseudo-shock waves. The LES results have been validated against experimental wall-pressure measurements. It shows good agreement with experimental results. Pseudo-shock length and corner separation have been studied in three-dimensional LES model. Comparison of centerline pressure measurement and 3D visualization measurement has been discussed for the corner separation position. It has been concluded that the pseudo-shock length should be measured by using 3D visualization measurement.

A CFD study on the Counterflow Thrust Vector Control

Ruoyu Deng,Heuy Dong Kim 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

Counterflow thrust vector control (TVC) has been preferably employed to control the thrust direction of propulsive systems due to the simple design and low cost. The main objective of this study has been to produce a detailed understanding on the TVC performance of the circular type counterflow concepts by CFD method. Numerical results have been compared with the previous experimental results in circular models. The CFD results using k-ε realizable turbulence model have showed quite good match with the experimental results. A portion of the flow in the circular type is split from primary jet and go through the suction passage. TVC performance is adversely affected because of the space utilization rate. For a given NPRp, the jet attachment point moves upstream as secondary suction pressure goes down.

Numerical Study on the Characteristics of Dual-Mode Scramjet Isolator

Ruoyu Deng,Heuy Dong Kim(김희동),Yingzi Jin 한국추진공학회 2015 한국추진공학회지 Vol.19 No.5

Control of Pseudo-Shock Wave Using Grooved Wall

Ruoyu Deng,Heuy Dong Kim 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12

The interaction between a normal shock wave and a boundary layer in the internal compressible flow is a very complicated flow. The interaction region containing shock train and mixing region is called as pseudo-shock wave. Nowadays, pseudo-shock wave becomes the key focus in many application fields. The objective of the present work is to investigate the effect of grooved walls on pseudo-shock wave. A computational fluid dynamics (CFD)-based study has been conducted for studying the flow field of pseudo-shock wave. The numerical results are in good agreement with the existing experimental results. The structure of pseudo-shock wave in the duct has been controlled by grooved walls. The counter-rotating vortices are produced by grooved control. The shocks become weaker in the core flow with grooved walls. It produces a beneficial reduction in total pressure loss.