Research On Flow And Heat Transfer Characteristics Of Impinging/Film With Inducting Slab

Experimental studies are conducted for f-type and t-type of impinging/film cooling structure with inducting slab on the background of aero-engine liner cooling structure.The effects of blowing ratio(M),temperature ratio(TR),turbulence intensity of hot flow(Tu),non-dimensional jet-to-plate pitch(z_n/d),non-dimensional spanwise spacing of jet holes(y_n/d),non-dimensional streamwise spacing of jet holes(x_n/d),cross-sections of inducting slab(rectangular and triangular)and diameter of jet hole(d)on the flow structure and overall cooling effectiveness were analyzed.Moreover,by means of simulation investigation,the effects of Knudsen number(Kn),turbulence intensity of hot flow(Tu),blowing ratio(M),density ratio(DR),velocity ratio(VR)and temperature ratio(TR)were also studied.Firstly,the actual geometrical dimensions of impinging/film structure were amplified.Consequently,the PIV(particle image velocimetry)was able to be utilized for investigating the flow structure of mipinging/film structure.The results showed that the increase of M moves the entraining vortices downstream,decreasing the hot gas close to the wall,however,enhancing the mixing in the shear layer because of the reinforced vortices on the end of inducting slab.The influence of TR(0.73~0.91)on flow structure of mipinging/film is unapparent.The augment of Tu strengths the mixing in the shear layer and the entraining effects at the exit of slot.The rise of z_n/d increases the size of entraining vortices,the depth of coolant film and the separation between the wall and coolant.The increase of y_n/d degrades the uniformity of velocity on the spanwise section;Compared to inducting slab with rectangular cross-sections,the one with triangular cross-sections removes the entraining vortices on the down of slot exit and the small vortices on the end of inducting slab,which decreases the mixing in the shear layer.The inducting slab with triangular cross-sections results in that coolant is attached to the wall effectively.Compared to the t-type of mipinging/film,the mixing of shear layer in the f-type is weaker and the f-type has a better performance for coolant flowing near the wall.Based on the studies above,simulation method was chosen after comparing the experimental data with the simulation data from 5 kinds of turbulence model respectively,for investigating the influence of kinds of dimensionless parameters on flow structure of impinging/film.The results indicated that Tu,TR and M have a prominent effect on flow structure while Kn,DR and VR are not the critical parameters for flow structure of impinging/film.Finally,overall cooling effectiveness of impinging/film structure with the actual geometrical dimensions was investigated.The effects of various flow parameter and geometrical parameters were studied and compared with the experimental data from PIV.Besides,the empirical correlations of average overall cooling effectiveness of liner were summed up.