Study On Wave Behavior And Structure Of Two-phase Oscillating Tube

Oscillating tube can realize the direct energy exchange between different pressure compressible media by using the moving wave system in the channel,which is commonly used in the field of gas dehumidification.The change of operating parameters in the refrigeration process can affect the internal wave system of the oscillating tube and further affect the refrigeration performance.When the incident gas contains condensable components,it is affected by the expansion wave and shock wave inside the oscillating tube,condensation and evaporation can occur.There is a lack of appropriate structural design methods to improve the performance of two-phase oscillating tubes.In view of the above problems,this paper carried out the following research work:(1)The CPA equation of state is introduced and the UDRGM module is used to establish a actual numerical model of non-equilibrium evaporation and condensation of condensed polar gas.Compared with the ideal gas,the influence of phase transition on the fluctuation behavior and energy loss in the pressure oscillating tube is obtained.The results show that compared with the experimental data of the expansion shock tube,the actual gas model can better describe the phase transition process in the unsteady flow than the ideal gas model.The incident shock peak of the actual gas model is lower than that of the ideal gas model at each pressure ratio,and the difference between the two increases with the increase of pressure ratio.Under different pressure ratio and relative humidity,the refrigeration performance of the two-phase oscillating tube calculated by the actual gas model is higher than that of the ideal gas model,and the difference increases with the increase of pressure ratio and relative humidity.As the relative humidity and pressure ratio increase,the isentropic expansion efficiency of the two-phase oscillation tube decreases while the dehumidification rate increases.In terms of energy loss,the incident entropy production decreases with the increase of relative humidity,and the decrease increases with the increase of pressure ratio.The entropy production of methanol-methane mixture is obviously less than that of water-methane mixture.(2)The influence of key operating parameters such as relative humidity,pressure ratio and rotational speed on the internal pressure fluctuation and refrigeration performance of the two-phase oscillating tube was tested by using the experimental platform of the two-phase oscillating tube.The results show that with the increase of relative humidity,the cooling efficiency of two-phase oscillation control gradually decreases,and the change trend is basically linear.Further increasing the pressure ratio,the adverse effect of relative humidity on the cooling efficiency of oscillation control is gradually reduced.As the pressure ratio increases,the number of condensed droplets and the incidence of entropy production decrease,which reduces the decrease in cooling efficiency.In addition,when the pressure ratio is the same,changing the incident gas from dry gas to saturated gas will reduce the optimal rotational speed.The results of the study on the fluctuation in the two-phase oscillating tube show that with the increase of the distance from the high-pressure port,the shock pressure gradually increases and gradually slows down,reaching a stable peak at 250 mm.With the increase of rotational speed,the peak pressure of shock wave decreases and the expansion depth first increases and then decreases.(3)The channel shape of the oscillating tube was improved by response surface optimization method,and a bending oscillating tube with improved refrigeration performance was obtained.The two-phase adaptability of the optimized oscillating tube was verified.The two-phase adaptability of the optimized oscillating tube was verified.The results show that the optimized oscillating tube has higher isentropic expansion efficiency than the original oscillating tube.The optimized rotor can significantly reduce the entropy production in the refrigeration process,especially the entropy production by velocity gradients.In addition,when the incident gas is water-methane,the dehumidification rate of the optimized oscillating tube is significantly higher than that of the original straight oscillating tube under different pressure ratios and inlet relative humidity.