Research On Thermal Analysis Of Aero-engine Bearing Chamber In Hot Zone

With the increment of modern aero-engine whole performance, the operational environment ofbearing chamber in hot zone becomes worse. Friction heat generations of seal and bearing, and hightemperature surroundings of bearing chamber bring a big danger to the reliability of aero-engine. Inview of the present research situation home and abroad, the investigations below have been done toimprove the research technique and computational accuracy of bearing chamber thermal analysis.Firstly, main heat sources of bearing chamber are analyzed. To provide the thermal boundaryconditions of numerical simulation of bearing chamber fluid solid coupled heat transfer characteristic,the computational models of friction heat generations of seal and bearing and heat transfer from hightemperature surroundings to bearing chamber are established and solved. Curves of friction heatgenerations with the change of shaft rotate speed are obtained. It can be found that heat generationswill be greater when rotate speed increases.Secondly, numerical simulation of bearing chamber fluid solid coupled heat transfercharacteristic is carried out. A simplified geometry of the bearing chamber behind turbine is set upwith UG. Based on the reasonable grid, boundary conditions and the experimental verification ofmultiphase flow model and turbulence model, the numerical simulation is launched. Distribution ofvelocity, pressure, temperature and volume fraction of oil in bearing chamber are obtained. Therelated rules of bearing chamber oil/air two-phase flow and heat transfer under different operatingconditions are summarized. And the optimal oil supply is analyzed.Lastly, oil film flow and heat transfer at the bearing chamber internal wall are discussed.According to the assumption that oil film is only driven by gravity, wall shear stress and rotating fluidshear stress, a force balance for a liquid film element is gained to build the theoretical model of oilfilm flow and heat transfer. The difference of models between high speed and low speed is analyzedto obtain the circular distribution of film thickness, average velocity and heat transfer coefficient.Some rules of oil film flow and heat transfer with the change of rotate speed and oil supply areconcluded.The conclusions in this thesis make a contribution to expand the design database of aero-engineoil system.