Numerical Simulation Of Interaction Between Condensation And High Speed Flows

Condensation phenomenon in compressible flow has always been an important re-search in fluid mechanics.It is a commonly seen physical phenomenon in human's daily life and widely used in industrial production.Water vapor condensation releases latent heat,under particular conditions,condensation shock waves is ensued,which would greatly change the flow field.In turn,the changes in the flow field would affect the vapor condensation.The interaction of condensation and flow field change makes the flow complicated and difficult to predict.Water vapor condensation also plays an im-portant role in turbine flow,cloud chamber,as well as in the periphery of the trailing edge of the supersonic aircraft wings.In recent years,with the fast development of com-puter technology and computing softwares,more and more new methods are available to assist the study of condensation.This thesis uses a series of new methods to study the condensation issues in high-speed flow,focusing on the analysis of condensation in Prandtl-Meyer flow in large domain and condensation-shock oscillation in nozzles.The main contents include:Firstly,we developed GPU parallel acceleration program for VAS2D algorithm in this article.Thanks to the new Fermi architecture GPU,we uses atomic operations to operate mesh adapting table with shared memory optimization,thereby achieving efficient GPU operation for the adaptive process.In this article we verified the validation of the GPU program by comparing the results and execution efficiency of the CPU(Intel E7300)serial program and the GPU(Geforce GT9800 and C2050)parallel program,which proved that the GPU parallel algorithm can achieve up to 40x speedup ratio.This also proved that the developments of computer structure can bring great benefits to CFD improvements.Then,we used the GPU-accelerated ASCE2D algorithm based on adaptive un-structured grids to calculate the condensation problem in the Prandtl-Meyer flow in large domain.In a small domain,there's only an individual shock wave,which accords with previous results well.In the numerical results of P-M flow with condensation in large domain,it shows that the condensation shock wave forms a step-by-step system.Shock wave in P-M flow with condensation is similar to condensation shock in time scale,in both radial direction and flow direction.In order to study the interaction between condensation and flow,we analyze the condensation shock oscillation in G2 nozzle with numerical method.The numerical re-sults show that in the process of condensation shock wave oscillation of the shock tube,even under the totally symmetrical conditions,the condensation shock wave oscillates in an asymmetric way under some circumstance,which is the same as results in the pre-vious numerical and experimental research.In this paper,the Fourier transformation is used to analyze the parameter of condensation shock in the G2 nozzle and we com-pared the difference of the shock oscillation in the half nozzle and the full nozzle.Then the instability of the nozzle condensation problem is analyzed by numerical analysis method.In this paper,it is preliminarily obtained that the asymmetric oscillation of the condensation shock wave is caused by the instability caused by the interaction between the condensation and the nozzle flow field.Finally,Using the user-defined scalar equation(UDS)and user-defined function(UDF)in Fluent,this paper calculated condensation problem in a shock tube with the moment method in Fluent.For shock tube problem,Fluent result is relatively valid,but it need further validation to verify the accuracy of UDS.