Analysis Of Various Cooling Schemes On A Combustion Chamber

Numerical studies are conducted for inclined-multi-hole cooling-, compound-angle cooling- and impingement/film cooing-structure respectively based on the liner cooling design parameters of a three-stage-swirl combustor in the present paper. The variation regularities of flow coefficient and cooling effectiveness are analyzed and compared among them with the same amount of the cooling air per area. The numerical results show that the cooling film of the inclined-multi-hole cooling structure is well developed at the location of about 7th or 8th row cooling hole downstream the first row for all the parameters studied. Besides, the decrease in the hole diameter will make an evidently increase in cooling effectiveness and a drop of the flow coefficient. The cooling effectiveness will decline a little as well as the little variation of the flow coefficient as the spanwise incline angle of the compound-angle cooing structure increases. With the larger diameter of the impinging hole, the wall temperature of the inducting slab decreases. It meanwhile improves the flow coefficient. The wall temperature of the liner downstream the cooling structure, however, does not make much change. For all the three cooling structures, the difference of the pressure between the two sides of the liner tends to decline when raising the ratio of the hole-area to the whole wall area. However, the changes of the cooling effectiveness give different results for the three different cooling structure due to an increase of that ratio. The inclined-multi-hole cooling- and compound-angle cooling-structure obtain higher cooling effectiveness while the impingement/film cooing-structure has lower one.According to the results of the numerical investigation, 7 different specific cooling schemes, which would be investigated experimentally, are designed on the basis of the three cooling structures mentioned above. The observations of the experiments show that the temperature of the liner increases with an improvement in the temperature of the inlet air or the fuel-air ratio. As the velocity of inlet air increases, the wall temperature drops slightly. For a cooling scheme which contains impingement/film cooling- and inclined-multi-hole cooling-structure, the increasing of the impingement-hole diameter makes the wall temperature decrease dramatically. However, it changes a little when increasing the diameter of the inclined-multi-hole. The wall temperature will decreases when using smaller diameter hole in the cooling scheme only consisting of the inclined-multi-hole cooling structure. And the flow of the primary holes plays an important role in the surrounding and downstream film development. The compound-angle cooling scheme does not show any advantages as compared to the inclined-multi-hole cooling scheme. The flow of the third stage swirl can cool the liner upstream the primary holes with no considerations on the inducting slab cooling.