Numerical Simulation Study On The Internal Flow Field And Aeroelastic Response Of The Impeller With Additional Tubular Vortex Reducer

As far as the tubular vortex reducer is concerned,its cooling effect is better.Experimental research also found that its own structure will produce vibration,which brings instability to the internal structure of the engine.Therefore,the main work of this paper has two points: one is to study the flow field of the high-pressure gas flowing out of the blade channel and the cooling air from the rotating disk cavity to the main shaft;the second is to study the aeroelastic response of the structure in the above process.In order to study the above two problems in depth,the specific form of the N-S equation flowing inside the impeller machine is derived,the vibration control equation of the structure under the action of aerodynamic force is given,and the two equations are coupled into the aeroelastic control equation.For the flow field equations,the finite volume discrete method is used to solve;for the structural dynamics equations,the finite element discrete method is used to solve;for the aeroelastic control equations,the separation solution method is used for single/bidirectional fluid-solid coupling analysis.The above analysis is based on three different geometric models,namely the empty rotating disc cavity,the attached tube rotating disc cavity and the tube hole integrated rotating disc cavity.A total of two sets of working conditions are set,one set is set at a constant speed of 2000 rpm,and the inlet and outlet static pressure ratio is increasing;the other is set with a constant inlet and outlet static pressure ratio of 2,which is an increasing speed.The specific analysis results obtained are as follows:For the empty rotating disc cavity,the flow capacity of the blade channel will decrease as the inlet and outlet static pressure ratio increases.The air flow in the rotor channel gradually changes from laminar flow to turbulent flow,and is on the pressure and suction sides of the rotor.A detached shock wave is generated;the cross shock wave first appears in the stator channel,and its intensity decreases with the increase of the outlet back pressure,until the shock wave converges on the side of the stator suction surface and finally disappears,and the flow field transitions to turbulence.On the side of the rotating disc cavity,it will be more and more difficult for gas to flow into the collection chamber,mainly because as the static pressure ratio increases,a backflow vortex will appear at the trailing edge of the rotor,causing some gas to flow out of the collection chamber to the blade channel.The gas entering the empty rotating disk cavity will form an asymmetric and unsteady vortex core area on both sides of the rear end of the inlet hole.The internal flow of the Ekman boundary layer is not laminar.Separation bubbles will appear.In general,it has almost no air-entraining ability.Regarding the tube-attached disk cavity,the flow of the blade channel is similar to that of the empty rotating disk cavity.The difference is that this model can achieve a higher inlet and outlet static pressure ratio.The outlet mass flow of the blade channel is significantly higher than that of the cavity model,although it is infinite The gas flow is lower and requires a higher total inlet pressure.Regarding the rotating disc cavity,the introduction of the vortex reducing tube can effectively guide the cooling air flow from the collecting chamber into the rotating main shaft section,and the gas mass flow out of the flange ring orifice is significantly increased,but it will also be on both sides of the rear end of the air inlet A large vortex core is formed,and part of the airflow rubs against the edge of the pipe inlet when it flows into the vortex reducer,and even forms a separation bubble on the inside of the pipe wall.Although the mass flow rate of the outflow of cold air is increasing,the energy loss of the gas is also increasing,and the energy of the outflow airflow will not change much.On the other hand,the vortex at both ends of the outer wall of the tube is the main cause of the vibration of the vortex reducing tube.For the tube-hole integrated disc cavity,the mass flow rate of the gas flowing out of the blade channel will be further reduced compared to the tube-attached disc cavity,and the mass flow rate of the gas ejected from the flange ring orifice will be further increased,and the total pressure loss of the gas flowing through the blade channel will gradually increase as the shock wave in the rotor channel increases and the turbulence pulsation in the whole channel increases.On the side of the rotating disc cavity,the total pressure loss of the gas is significantly reduced.The gas directly enters the vortex reducing tube after passing through the air inlet and generates a mixing vortex inside the joint structure.Small separation bubbles will form on the inside of the tube wall,but the flow pattern is relatively more.Smooth,less energy loss.Compared with the attached tube disc cavity,its air-entraining capacity is further enhanced;the disadvantage is that the isentropic efficiency of the blade work is reduced,and the airflow quality in the high-pressure section will be lost.On the other hand,the new configuration can reduce the maximum deformation of the structure,making the internal disc cavity of the compressor more stable.In terms of the analysis of aeroelastic results,the prestressed modal analysis can obtain the7 modes with the highest effective participation quality.Almost every mode includes the vibration of the rotating spindle in various directions,predicting the most likely vibration form of the overall structure.From the one-way fluid-solid coupling analysis,the vibration amplitude of the blade and the rotating main shaft under aerodynamic force is much smaller than that of the rotating disc cavity,and the integrated pipe-hole model can effectively reduce the maximum deformation and slightly increase the average deformation.The two-way fluid-solid coupling analysis shows that the vibration deformation of the disc cavity structure is more smooth,and the maximum deformation amplitude of the integrated model of management and control shows a gradual attenuation trend.The paper has 84 pictures,13 tables,and 51 references.