Fundamentally Studies On The Double-ducker Cooling Structures Of Impingment With Film Outflow In Rotating State

Impinging cooling with film outflow is a typical cooling technique in gas turbine engine. In this thesis, fundamental investigations were carried out to study the flow and heat transfer of impingement with film outflow in the double-ducker structure of cast cool turbine blade.Firstly, in static state, experiments were carried out to investigate the characteristics of heat transfer on jet plate in the double-ducker structure affected by the vortex, which is induced by the impinging in limited and small space. The parameters including Reynolds number and the ratio of the jet impingement distance to the diameter of the jet hole H/D were changed to study the local heat transfer coefficient and the characteristic of heat transfer inside the double-ducker structure. The experimental results show that the rate of heat flux on jet plate to total heat flux q 2 /q1 becomes smaller with Re increasing, while q 2 /q1 varying with H/D is not monotonously. All the results show that the coolant can transport more heat to the jet plate under the effect of vortex enhancement. It was shown in experiments that the influenced region of vortex on jet plate was limited in the range of 4.5 ~ 8D around the jet hole and 10%~20% of heat was transported to the jet plate in different experimental parameters.Furthermore, in rotating state, numerical simulations were applied to study the flow and heat transfer of the impingement with film outflow in the double-ducker. To show the applicability of turbulent model in rotating situation, additional numerical tests were carried out and the SST k -ωtwo-equation turbulent model was chosen to understand the characteristic of flow and heat transfer in the double-ducker structure.It was observed in numerical simulations that the effects of rotation centrifugal force and Coriolis force on impinging jet and film outflow were different. Impinging jet can be deflexed and film outflow can be accelerated. In vertical impinging the cooling effectiveness decreases with H/D increasing, while the cooling effectiveness varying with H/D is not monotonously in incline impinging(30 deg). In simulation, the blowing ratio (M) was varied from 0.5 to 1.5, the cooling effectiveness increases with M increasing when jet angle equals 90 deg, while the cooling effectiveness is not monotonously when jet angle equals 30 deg,.All the research results show that the parameters of rotation,geometrical and the blowing ratio (M) affect the impinging jet and film outflow at the same time, and the rules of heat transfer and cooling coefficient varying with these parameters are quite complicated.