Low-speed Wind Tunnel Optimization Design And Its Application In The Flow Field Analysis Of Aero-engine Deformed Gears

As is known to all,aerodynamic research is closely related to the development of wind tunnel experiments.With the rapid development of various fields,the common low-speed wind tunnels in domestic colleges and universities are gradually difficult to meet the needs of all walks of life.However,the construction of new high-speed wind tunnels is time-consuming and labor-intensive,and the cost is high.Therefore,how to optimize the design of existing low-speed wind tunnels is of great significance for the future wind tunnel experimental research.In this thesis,the structure improvement and 3D full flow field numerical simulation are carried out for the open-close dual-purpose backflow low-speed wind tunnel with the size of400 mm × 300 mm in the experimental section.The optimization design is focused on the contraction section influence on the flow characteristics of the wind tunnel.The flow field quality is ensured while the flow velocity is increased.The numerical simulation is carried out for the models with different structural parameters.The calculation results are analyzed and compared,and the structure with the best performance is selected and verified by experiments.The main research contents are as follows :1.The research work of scholars in China and abroad on low-speed wind tunnel is summarized and discussed.Based on the three equations of fluid mechanics,the principle of convergence structure is analyzed and summarized.The three-dimensional drawing software Solidworks was used to establish three binary shrinkage curve models of Vickers,bicubic and quintic respectively.Through the Fluent fluid mechanics analysis software,the flow characteristics parameters such as velocity,pressure,turbulence intensity and flow field trace were compared and analyzed.It was found that the bicubic and quintic curves were more suitable for the size structure.2.The obtained curve model was further optimized,and the flow field characteristics under different inlet angles of contraction section and the length of stable section were compared in the simulation software.The final size was determined as the inlet angle of contraction section of 70°,the length of stable section of 0.6 m,and the model of detachable experimental section of 0.3 m was added to meet the experimental needs under different conditions.3.The whole flow field simulation was carried out for the two wind tunnel models before and after the optimization and improvement of the wind tunnel test section,and the flow field quality and the overall operation of the wind tunnel equipment before and after the improvement were investigated.The results show that the wind tunnel with the structural parameters has stable internal flow field,high wind speed and small turbulence,which can be used for experimental research.4.The experimental field is arranged by setting up the convergence model designed above,and the flow field data before and after the wind tunnel optimization are recorded by using the measurement equipment.The comparison shows that the overall flow field distribution is not significantly different from the simulation results,and the deformation tooth damage experiment of aeroengine can be carried out.The experiment shows that the stress of the deformation tooth satisfies the rotational symmetry.the tooth tip stress is greater than the middle of the tooth;under the same experimental conditions,the flow velocity increases slightly and the strain increases when the internal bending angle is small,and the flow velocity decreases and the strain decreases when the internal bending angle is large.The purpose of this thesis is to obtain the wind tunnel experimental platform that the flow field quality meets the experimental requirements through the optimization design of the existing wind tunnel,and on this basis to carry out the related research of aero-engine deformation teeth.The design can not only meet the basic needs of aviation engineering research work,but also can be used for general teaching experiments and aerodynamic simulation experiments,which has practical significance for the popularization and application of wind tunnel improvement and optimization.