Temperature Distortion Characteristics In S-Duct Inlet And Its Influence On Micro Jet Engine

IDDES numerical simulation and ground suction experiments are used to study the ingestion characteristics of typical S duct inlet with high-temperature heat source under conditions of free stream and ground running.The characteristics of high-temperature flow in serpentine inlet,the characteristics of boundary layer development and the temperature distortion at inlet outlet are obtained.A temperature distortion simulator based on the injection of high-temperature jet is designed to simulate the spatial distribution characteristics of the temperature distortion flowfield at the outlet.The temperature distortion simulator is combined with a small-flow turbojet engine,and an experimental platform is built to test the effect of temperature distortion on the performance of the centrifugal compressor and the engine.(1)The structure of turbulent boundary layer in serpentine inlet has an important influence on the spatial distribution and fluctuation characteristics of the external high-temperature heat source.When the high-temperature heat source enters the inlet through the core region of the inlet,the temperature distortion flowfield with the characteristic of the whole temperature reduction forms through the convection heat transfer at the outlet.The phenomenon is caused by the temperature gradient between the high-temperature region of mainstream and the low-temperature region of the boundary layer.When the high-temperature heat source enters the inlet through boundary layer of the inlet,the accumulation of boundary layer from upper wall to lower wall after first corner leads to the uneven distribution of circumferential temperature at the inlet outlet.The transport from the boundary layer to the high-temperature heat source is the main factor leading to the circumferential temperature distortion.The fluctuation characteristics of the exit temperature distortion were determined by the fluctuation of the turbulent boundary layer in the inlet.(2)As for the transient inhalation of high-temperature heat source,the turbulent boundary layer of the inlet has a blocking effect on the temperature rise rate at the outlet.(3)The temperature distortion pattern is obtained by the superposition of the basic temperature distortion flowfield generated by high-temperature jet.Then the feasibility and the effectiveness of the simulator is verified by experiments.(4)Owing to the inlet temperature distortion,the compressor pressure ratio decreases whereas the compressor pressure fluctuation frequency increases.What's more,the thrust declines and the fuel consumption rises.This study will provide a reference for the development of temperature distortion simulator,and a technical support for the test of temperature distortion of the engine inlet.