| The thrust of an aero-engine is one of the most important indicators of engine performance.In the process of engine development,production and maintenance,it needs to be measured by a large number of ground test tests,and most of these tests usually rely on the outdoor test stand,so it is important to study the flow field distribution law of the outdoor test stand under different environmental conditions.In this paper,we investigate the suitable thrust correction method for the open-air test bench and study the design optimization scheme of sand swallowing test based on the simulation of the flow field of the outdoor test stand.Firstly,the study of the numerical simulation method of the flow field of the open-air test bench was carried out,and the reliability of the numerical simulation of the flow field of the open-air bench in this paper was verified by comparing and analyzing the experimental data with the numerical simulation results.On this basis,numerical simulations were carried out to investigate the effects of environmental conditions on the flow field and engine inlet characteristics of an aero-engine under different natural wind speeds(0 to 5m/s),wind directions(0 to 90°)and ground heights(4 to 7m)in open-air test runs.It is found that the natural wind conditions significantly affect the distribution of the return area near the engine inlet of the test stand,while the side wind causes distortion of the engine inlet flow field,and the engine installation height less than 6m will significantly reduce its intake flow rate,and the lower the installation height,the greater the impact.By analyzing the flow field distribution characteristics around the engine inlet tract and the inlet tract aerodynamic intersection under different natural wind conditions,it was found that the previous indoor test stand thrust correction method based on the measurement of secondary airflow could not be used for the outdoor test stand;the formula for calculating the additional drag of the aero-engine inlet applicable to the open-air test stand was derived by the internal flow method,and on this basis,combined with the simulation results,the additional drag of the engine inlet and the windward drag of the outdoor test stand were calculated.The additional drag and the windward drag of the test stand are calculated on the basis of the simulation results,and the influence of the wind speed on the modified drag is analyzed.The research results provide theoretical research help for the actual outdoor test stand to be carried out,and give guidance for measuring the thrust correction.According to the study to obtain the influence law of natural wind conditions on the amount of thrust correction of the outdoor test stand,the environment conditions of the outdoor test stand are given.Based on the study of the pneumatic flow field of the outdoor test stand,this paper then conducts a numerical simulation study of the flow field of the sand ingestion test conducted on the open-air test bench to give the trajectory and concentration distribution law of the sand particles in the flow field.Through the simulation calculation of sand swallowing test under different sand types(national military standard specified sand,typical coarse sand,typical fine sand)and test equipment structure parameters such as sand blasting device baffle angle(30° to 45°),rectifier diameter(1700mm to 2300mm),sand blasting device and engine distance(1000mm to 1750mm),it is found that sand type affects the distribution of sand in the flow field It was found that the sand type would affect the distribution of sand in the flow field and cause the sand concentration in the inlet section of the engine to be in error with the national military standard of 0.053kg/m~3.At the same time,the influence law of the above test structure parameters on the unevenness of sand distribution in the engine inlet flow field was studied in detail,and orthogonal tests were conducted to optimize the combination of the structural parameters of the sand swallowing device by integrating three factors,and the best test solution was given with the baffle angle of 30°,the finishing diameter of 1700mm and the distance between the sand blasting device and the engine of 1000mm. |
