The Impact Of Thermocouple Arrangement On Fire Test Of Aero-engine

Aircraft engine fire test is an important means and an important part of engine airworthiness verification.Aircraft engine fire test can simulate the actual situation objectively and veritably,to avoid the one-sided results that the theoretical simplification may lead to.While the fire test also has the characteristics of repeatability,it is often selected by the major authorities to verify the fire performance Consistency with Airworthiness.However,the AC20-135 requires that the flame of the burner must be calibrated with thermocouples before conducting the fire test.There are many factors that affect the fire test.This paper mainly studies the influence of the arrangement of thermocouple on flame temperature calibration.In this paper,numerical simulation is used to model the NexGen burner and thermocouple as defined in AC20-135.By analyzing the velocity field,temperature field,heat flux field and the concentration of each component,it is determined that the position of the thermocouple will have an effect on the measure of temperature of the flame.Firstly,the simulation of free flame is carried out to determine the feasibility of the physical model and the initial conditions in the simulation process.The flame is obtained and the flame characteristics are analyzed.The flame temperature,heat flux and the concentration of each component are determined.And the grid independence and validity of the simulation results are studied.Secondly,this paper studies the situation that one thermocouple is placed at the temperature calibration position specified in the regulations.By studying the flame characteristics under one thermocouple,the influence of thermocouple calibration position on the temperature value is given,which can provide reference for the arrangement of multi-thermocouples.Finally,according to the simulation results of single thermocouple,the influence of different arrangement of double thermocouples on temperature calibration is studied,and the validity of simulation results of seven thermocouples is verified.Then,according to the simulation results under double thermocouples,two new thermocouple arrangement methods are proposed,and the effect of the new arrangements on the temperature calibration is determined by comparing with the results of the conventional arrangement.