Research On Vibration Characteristic Of Gas Wave Refrigerator Rotor Based On Thermal-fluid-solid Coupling Method

The double-opening gas wave refrigerator has the advantages of simple structure,adjustable parameters,high cooling efficiency and liquid operation.Therefore,it is widely used in the aerospace,low-temperature wind tunnel experiments,natural gas dehydration and industrial exhaust recovery.At present,the research on the gas wave refrigerator mainly focuses on the two-dimensional numerical simulation of the unsteady flow of the fluid in the oscillating tube,the thermodynamic characteristics and the experiment of refrigeration efficiency.However,there is few research on the dynamic response of the structure such as the thermalfluid-solid coupling calculation and vibration characteristics of the gas wave refrigerator.With the development of gas wave refrigerator equipment in the direction of high-pressure and largescale,it is applied to harsh working conditions such as high frequency and low temperature.Therefore,the research on the reliability issues such as the unsteady intensity and vibration response of the gas wave refrigerator is becoming more and more important.In this paper,the unsteady strength and vibration characteristics of the gas wave refrigerator are further studied based on the thermal-fluid-solid coupling method.The structure and working principle of the double-opening gas wave refrigerator are firstly studied.The three-dimensional numerical model of the gas wave refrigerator is developed,and the numerical calculation results are verified.In addition,the characteristics of the pressure field,temperature field and velocity field of the unsteady flowing fluid in the oscillating tube are analyzed in detail.The key process of high-pressure nozzle gas injection into the oscillating tube is further studied,and the excitation loads at multiple special points in the oscillating tube are extracted.Based on the fast Fourier transform,the frequency domain characteristics of the pressure fluctuation for the corresponding fluid are obtained.It provides a basis for further research on the pressure exchange refrigeration mechanism,heat-fluid-solid coupling calculation and dynamic response analysis of the gas wave refrigerator.Then,the paper used a combination of experiment and numerical analysis to develop a thermo-fluid-solid coupling model for the gas wave refrigerator rotor,and verified the reliability of the numerical simulation.At the same time,the distribution of stress and deformation of the wave rotor under the mechanical loads such as gravity,centrifugal force,pulsating pressure and thermal loads are analyzed,and the structural danger points are determined.The research results show that the centrifugal force and temperature load play an important role in the strength and deformation of the gas wave refrigerator,especially the temperature load.And the frequency of the first three orders at the maximum dynamic stress of the oscillating tube under fluid-solid coupling is close to the unsteady calculation of the pressure pulsation.Finally,the vibration characteristics of the wave rotor system such as the constrained mode,gravity and centrifugal force,the fluid-solid coupling mode,and the thermal mode are studied,and the main excitation sources that affect the vibration of the gas wave refrigerator are analyzed.The research results show that the first-order natural frequency of the wave rotor system in the constrained mode is 76.1Hz,and the vibration modes mainly include axial torsion and expansion,symmetrical swing,axial expansion and so on.In addition,the modal frequency and vibration amplitude deviation of the wave rotor system under the pre-stress of gravity,fluid pressure,and thermal stress is small,while the frequency of the first three modes is significantly lower under the centrifugal force.Moreover,the main frequency of the fluid pressure in the oscillating tube and the natural frequency of the wave rotor are in the resonance zone,so the excitation force of the fluid is likely to cause resonance of the gas wave refrigerator.The research results provide a theoretical basis for the vibration reduction design and fault diagnosis of the gas wave refrigerator,so as to ensure its smooth and safe operation.