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A Parametric Study of the Dump Diffuser Flow
V.R. Sanal Kumar,S. Deshpande,김희동(H.D. Kim),T. Setoguchi 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
The dump diffuser produces a stable flow pattern under a wide range of operating conditions. Many experimental and numerical studies have been reported on dump diffuser flows with tremendous insight on critical flow features. Nevertheless, the design optimization of dump diffuser is still an emerging field in the modern aircraft industry. Towards meeting the design objectives, using a two-dimensional standard k-ε turbulence model, in this paper parametric studies have been carried out to examine the flow features through a straight-walled pre-diffuser with a dump.
A Study of the Flow Characteristics through a Dump Diffuser
Srikanth V. Deshpande,V.R. Sanal Kumar,H.D. Kim(김희동) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Experimental and numerical studies have been carried out to examine the internal flow features of dump diffusers with straight walled pre-diffuser at different inlet velocities. Experimental studies have been carried out in a wind tunnel facility. Numerical studies have been carried out using a two-dimensional standard kepsilon turbulence model. It was observed that at sufficiently low inlet velocities the experimental and the computational values are comparable. It was observed that a favorable pressure recovery can be obtained and the compressed air with high axial velocity can be decelerated to low values in order to facilitate efficient combustion in the flame tube zone. The observations made here lead us to execute more parametric studies in order to understand the flow conditions better and for optimized design of a dump diffuser.
정미선(Mi-Seon Jeong),V. R. Sanal Kumar,김회동(Heuy-Dong Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
In steel-making process of iron and steel industry, the purity and quality of steel can be dependent on the<br/> amount of CO contained in the molten metal. Recently, the supersonic oxygen jet is being applied to the<br/> molten metal in the electric furnace and thus reduces the CO amount through the chemical reactions between<br/> the oxygen jet and molten metal, leading to a better quality of steel. In this application, the supersonic oxygen<br/> jet is limited in the distance over which the supersonic velocity is maintained. In order to get longer<br/> supersonic jet propagation into the molten metal, a supersonic coherent jet is suggested as one of the<br/> alternatives which are applicable to the electric furnace system. It has a flame around the conventional<br/> supersonic jet and thus the entrainment effect of the surrounding gas into the supersonic jet is reduced, leading<br/> to a longer propagation of the supersonic jet. In this regard, gasdynamics mechanism about why the<br/> combustion phenomenon surrounding the supersonic jet causes the jet core length to be longer is not yet<br/> clarified. The present study investigates the major characteristics of the supersonic coherent jet, compared<br/> with the conventional supersonic jet. A computational study is carried out to solve the compressible,<br/> axisymmetric Navier-Stokes equations. The computational results of the supersonic coherent jet are compared<br/> with the conventional supersonic jets.
적외선 카메라를 이용한 초음속 충돌 동축제트의 벽면 온도 측정
곽종호(Jong-Ho Gwak),V. R. Sanal Kumar,김희동(Heuy-Dong Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
The supersonic impinging jet has been extensively applied to rocket launching system, gas jet cutting control, gas turbine blade cooling, etc. In such applications, wall temperature of an object on which supersonic jet impinges is a very important factor to determine the performance and life of the device. However, wall temperature data of supersonic impinging jets are not enough to data. The present study describes an experimental work to measure the wall temperatures of a vertical flat plate on which supersonic, dual, coaxial jet impinges. An Infrared camera is employed to measure the wall temperature distribution on the impinging plate. The pressure ratio of the jet is varied to obtain the supersonic jets in the range of over-expanded to moderately under-expanded conditions at the exit of coaxial nozzle. The distance between the coaxial nozzle and the flat plate was also varied. The coaxial jet flows are visualized using a Shadow optical method. The results show that the wall temperature distribution of the impinging plate is strongly dependent on the jet pressure ratio and the distance between the nozzle and plate.
Coflow-Counterflow개념을 이용한 추력벡터 노즐에서 발생하는 유동특성에 관한 연구
정성재(Sung-Jae Jung),V. R. Sanal Kumar,김희동(Heuy-Dong Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Thrust vector control using a coflow-counterflow concept is achieved by suction and blowing through a<br/> slot adjacent to a primary jet which is shrouded by a suction collar. In the present study, the flow<br/> characteristics of thrust vectoring is investigated using a numerical method. The nozzle has a design Mach<br/> number of 2.0, and the operation pressure ratio is varied to obtain various flow features of the nozzle flow.<br/> Test conditions are in the range of the nozzle pressure ratio from 6.0 to 10.0, and a suction pressure from<br/> 90kPa to 35kPa. Two-dimensional, compressible Navier-Stokes computations are conducted with RNG k-ε<br/> turbulence model. The computational results provide an understanding of the detailed physics of the thrust<br/> vectoring process. It is found that an increase in the nozzle pressure ratio leads to increased thrust efficiency<br/> but reduces the thrust vector angle.
Conceptual Aerodynamic Design of Pintle Nozzle for Variable-Thrust Propulsion
Vignesh Saravanan,고정우,이수갑,Nijanthan Murugan,V. R. Sanal Kumar 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.1
Comprehensive theoretical studies have been carried out for the geometry optimization of a pintle nozzle for variable-thrust propulsion. We designed the pintle such that, at the final pintle position, the integrated shape facilitates the scaled-down version of the shockless main nozzle. Numerical studies have been carried out using a validated two-dimensional transient, an implicit Reynolds-averaged Navier–Stokes equations (RANS) solver with a k–ω Menter’s shear stress transport (SST) turbulence model. At the quasi-steady and dynamic conditions, the numerical results have shown excellent agreement with the theoretical results. In the dynamic condition, the effects of shock train, shock impinging, and the shock location on the overall thrust are studied, and we observed a monotonic increase in thrust during the pintle movement toward the exit and achieved the maximum thrust at the highest area ratio (nozzle exit area to throat area) position. The diminishing of the shock–strength pattern and the movement of the shock-impinging point towards the nozzle exit are captured in the numerical simulation and reported herein. We concluded that the prudent aerodynamic shape optimization of the external surface contour of the pintle and the inner surface contour of its associated nozzle ensures improved performance for the variable-thrust propulsion of aerospace vehicles.