Research On Measurement Method Of Aero-Engine Tail Injection Temperature Field Based On Schlieren Method

As the core power unit of the aircraft,if we can monitor the running state of the engine,we can improve the safety and economy of the aircraft.The temperature field of aero-engine tail injection contains effective information such as the degree of fuel combustion inside the combustion chamber and the degree of aging of the gas path.The monitoring of aero-engines is an effective means to evaluate the operating conditions of the engines.This subject intends to research a non-contact temperature field measurement method based on the schlieren method to satisfied the measurement requirements of the aero-engine exhaust temperature field.The principle of the schlieren method is studied in this paper,the measurement model,the calibration of the schlieren method and the specific application of the Abel inverse transform algorithm in the reconstruction of the axisymmetric temperature field.In the process of simulation and verification of the reconstruction of the temperature field,a temperature field conforming to the Gaussian distribution needs to be given.First of all,it is necessary to obtain the deviation of the light after the light passes through the temperature field,and determine the deflection angle of the light according to the geometric relationship.Then the Abel inverse transform algorithm is used to obtain the refractive index gradient distribution of the temperature field.Finally,according to the Gladstone-Dale theorem and the ideal gas state equation,the temperature distribution is solved and the true value is compared to obtain the error.Based on the above,the feasibility of the axisymmetric temperature field reconstruction algorithm of the transmission schlieren method can be verified.The principle of rotating tomography schlieren method,and projection reconstruction algorithm,and the design of rotating tomography mechanism of three-dimensional measurement system are researched.In the process of simulation and verification for the reconstruction of the temperature field,a transverse section of a non-axial symmetry distributed three-dimensional temperature field needs to be given.First of all,the projection of the tangent surface of the temperature field is obtained.Then,the inverse Radon transform is used to obtain the refractive index gradient distribution of the transverse section of the temperature field.Finally,according to the Gladstone-Dale theorem and the ideal gas state equation,the temperature distribution is obtained,and the error is obtained by comparing the true value.The feasibility of the non-axisymmetric temperature field reconstruction algorithm of the rotating tomographic schlieren method has been verified.In order to realize the multi-angle measurement of the measured temperature field by the rotating tomographic schlieren method,the rotating tomographic mechanism is designed and manufactured.This device can be effectively applied to the three-dimensional creation of the temperature field.Research on the simulation measurement experiment of aero-engine on the proposed aero-engine tail injection temperature field measurement method.The experiment was carried out with a built-up transmission schlieren measurement system.First,Bunsen burner is selected to simulate the temperature field of engine tail injection.The transmission schlieren reconstruction method is applied to the temperature field measurement,and the proposed method is verified through experiments.Then the non-axisymmetric temperature field reconstruction of the rotating tomography method is applied to the temperature field measurement.In addition,the results measurement accuracy of this method is verified based on the thermocouple.Finally,the boundary conditions of the temperature field of the micro turbojet engine are measured,and the temperature field of this type of engine is modeled,analyzed and calculated by means of fluid dynamics.According to the analysis of the simulation results,the non-axisymmetric temperature field reconstruction method of the rotation tomography method can be applied to the three-dimensional measurement of the aero-engine exhaust temperature field.