An Analysis of Jet Noise Characteristics in the Compressible Turbulent Mixing Layer of a Standard Nozzle

Abstract

In this paper, we seek to understand the influence of TPS standard nozzle shape on jet noise and improve the accuracy of flow and pressure ratio of aeronautical simulation. Through the structural design of an equal-diameter nozzle and a standard nozzle, a concentric dichotomy monitoring point arrangement scheme is proposed for its flow field and sound field, and the free flow of the jet is used to realize k − ε. The model is solved by hydrodynamics to analyze the flow characteristics of the turbulent boundary layer, and the near-field and far-field characteristics of jet noise are analyzed by using the Lighthill equation excited by a quadrupole under fluid input, revealing the turbulent velocity and turbulent kinetic energy and other relevant fluid characteristics of the two nozzles under a single variable, and analyzing the near-field and far-field noise pressure levels and directivity of the two nozzles at a specific frequency. When the boundary conditions are consistent, the change trends and laws of the two kinds of nozzles in the turbulent jet flow field are almost the same, and the eddy viscosity extreme value of the standard nozzle is 0.02 higher than that of the equal-diameter nozzle, while the static temperature extreme value is 8 K, but they have a great impact in the noise field, mainly reflected in the noise decreasing law, noise directivity and low-frequency noise distribution. The mean value of noise extremes of standard nozzles at four frequencies is 2 dB higher than that of equal-diameter nozzles. The relative characteristics of the two nozzles can be used to design through the actual demand conditions of the flow field and the sound field by providing a reference for the customized parameter design of the standard nozzle.