Research On The Sealing Flow And Flow Heat Transfer In The Cavity Between High And Low Pressure Rotors Of A Vaneless Counter-Rotating Turbine

Obtaining flow parameters for the secondary air system of counter-rotating aero engines is meaningful for the structure design of the secondary air system and the calculation of the axial force of the engine.There are complex flow and heat transfer phenomenon in the counter-rotating turbine cavity of a counter-rotating aero engine.In order optimize the secondary air system of counter-rotating aero engines,detailed flow and heat transfer characteristics in the counter-rotating turbine cavity need to be discussed.A lot of research has been performed on the secondary air system of conventional engines to show the flow field and heat transfer in the stator-rotor cavity.However the effects of the counter rotating high pressure and low pressure rotors on the flow field of the turbine cavity have not been well analyzied.Therefore further discussion is needed for the flow and heat transfer in the counter-rotating turbine cavity.This paper presents design method and numerical simulation for the secondary air system of a vanless counter-rotating engine,for better understanding of the flow and heat transfer characteristics of the counter-rotating turbine cavity.The research work can be summarized as follows:1?One dimensional networking of the secondary air system of a vaneless counter-rotating engine is realized,And the work generated by counter-rotating walls,which influences the flow parameters,is considered.Then,by solving nonlinear equations abstracted from the secondary air system and obtain flow parameters.Last,the one-dimensional calculation results are compared with two-dimensional and three-dimensional numerical results.It is found that one-dimensional calculation results are credible.2?Three-dimensional numerical simulation of steady flow in the computing domain at the counter-rotating turbine cavity is carried out.The influence of mainstream pressure on the flow at the rim seal of the counter-rotating cavity is analyzed.It is found that if the sealing flow is not enough,the mainstream ingress into the counter-rotating turbine cavity at the high pressure zone of high pressure rotors trailing edge and low pressure rotors leading edge.3?The flow and heat transfer in the counter-rotating cavity,which velocity ratio is less than-1 and sealing flow is enough,were analyzed.It is obtained that the flow and heat transfer on the high pressure wheel surface in the source region are dominated by the cooling flow intake inertia.And other regions,including the whole range of the low pressure wheel surface and the high pressure wheel surface out of the source region,the flow and heat transfer are dominated by the disk rotation;It is found that the flow and heat transfer are seriously influenced by the circumferential non-uniform distribution of the mainstream pressure.The distribution of the mainstream circumferential pressure directly affects the flow and the radial distribution of Nur on the rim seal surface.4?When the rotating speed of the high pressure plate is kept constant and the rotating speed of the low-pressure wheel is reduced,the Nur of the low pressure wheel surface decreases gradually.In addition,the Nur of the low pressure rim seal surface increases gradually.The flow and heat transfer on the high pressure wheel surface are little affected by the change of the low pressure wheel speed.The flow on the high pressure rim seal surface is increasingly influenced by the flow in the counter-rotating cavity.