Numerical Study On Aerodynamic Characteristics Of Supersonic Nozzle In Presence Of Ground Effect

Abstract

Abstract The aeroengine mobile test bench is well applied as it is convenient for outfield transportation and installation, and also it is suitable for different environments. When utilizing a mobile test bench, the distance between the center of the engine and the ground is normally within a range so that it can be manually operated. However, this limited distance will lead to the ground effect, which affects the test performance of the aeroengine. This paper numerically studies the aerodynamic characteristics of a supersonic nozzle in the presence of the ground effect. The work is conducted with the software package ANSYS Fluent 21, employing the unsteady large eddy simulation. The nozzle works in a supersonic condition, and the distance between the nozzle and the ground is 2Dj. Dj is the diameter of the nozzle outlet. The models with and without ground effect are investigated. The analysis of the flow field confirms that the ground effect enhances the mixing of the jet and the air, and enriches the coherent structure. With the ground effect, the Reynolds stress on the vertical centerline on each section plane is increased, and the shear layer on each section plane is expanded radially. The results show that the ground effect increases the ground temperature after x/Dj=9, shortens the length of the core area by about 12.5%, decreases the mean axial velocity on the centerline of the jet after x/Dj=10, and increases the dimensionless velocity on the near ground side of the vertical plane. Here, x is the distance between the inlet plane and the discussed cross section. The analysis of the thrust characteristics confirms that the ground effect has no influence on the thrust. Therefore, the mobile test bench can accurately evaluate the thrust performance of an aeroengine.