A test rig is constructed to investigate the effects of vortex generator height on film cooling property. The thermocouples and the technology of Particle Image Velocimetry(PIV)are used to measure the wall temperature and visualize the flow distribution. The experiment is carried out in a single-jet structure with an inclination angle of 20 degrees. The scale of turbulence and the blowing ratio are set to be 0.4% and 1.5 respectively. The film cooling effectiveness and the flow structure in the vortex generators of five different heights are measured. It indicates that the film cooling performance can be significantly improved by the vortex generator
and the performance of the vortex generator is obviously affected by the height. With the increasing height of the vortex generator
the performance of the vortex generator is first enhanced and then deteriorated. At the optimal height
the average film cooling effectiveness of the plate equipped with vortex generator is increased by 81% compared with the case without vortex generator. Analyzing the PIV flow
the enhancement of film cooling is found owing to the formation of anti-kidney pair of vortices. However
in the shortest height model the anti-kidney vortices generated is too weak to effectively transport the jet toward the wall
while in the highest height model the vortex generator penetrates into the hot gas entrained into the strong anti-kidney vortices to decline the cooling effectiveness.
关键词
Keywords
references
HAN J, DUTTA S, EKKAD S. Gas turbine heat transfer and cooling technology [M]. Abingdon, UK: CRC Press, 2012: 159-160.
FRIC T F, ROSHKO A. Vortical structure in the wake of a transverse jet [J]. Journal of Fluid Mechanics, 1994, 279: 1-47.
GOLDSTEIN R J, ECKERT E, BURGGRAF F. Effects of hole geometry and density on three-dimensional film cooling [J]. International Journal of Heat and Mass Transfer, 1974, 17(5): 595-607.
HEIDMANN J D, EKKAD S. A novel antivortex turbine film-cooling hole concept [J]. ASME Journal of Turbomachinery, 2008, 130(3): 31020.
DHUNGEL S, PHILLIPS A, EKKAD S V, et al. Experimental investigation of a novel anti-vortex film cooling hole design: GT2007-27419 [R]. New York, USA: ASME, 2007.
NA S, SHIH T I. Increasing adiabatic film-cooling effectiveness by using an upstream ramp [J]. ASME Journal of Heat Transfer, 2007, 129(4): 464-471.
BARIGOZZI G, FRANCHINI G, PERDICHIZZI A. The effect of an upstream ramp on cylindrical and fan-shaped hole film cooling: part I Aerodynamic results [C]∥ASME Turbo Expo 2007. New York, USA: ASME, 2007: 105-113.
SAKAI E, TAKAHASHI T, AGATA Y. Experimental Study on effects of internal ribs and rear bumps on film cooling effectiveness [J]. ASME Journal of Turbomachinery, 2013, 135(3): 031025.
KFYS H K. Improvement of turbine vane film cooling performance by double flow control devices [J]. ASME Journal of Turbomachinery, 2016, 138(11): 111005.
RIGBY D L, HEIDMANN J D. Improved film cooling effectiveness by placing a vortex generator downstream of each hole [C]∥ASME Turbo Expo 2008: Power for Land, Sea, and Air. New York, USA: ASME, 2008: 1161-1174.
ZAMAN K B M Q, RIGBY D L, HEIDMANN J D. Experimental study of an inclined jet-in-cross-flow interacting with a vortex generator [C]∥48th AIAA Aerospace Sciences Meeting. Reston, VA, USA: AIAA, 2010: 4-7.
SHINN A F, VANKA S P. Large eddy simulations of film-cooling flows with a micro-ramp vortex generator [J]. ASME Journal of Turbomachinery, 2013, 135: 0110041.