Analysis And Comparison Of Turbulence Model In Simulation Of Impinging Jet Flow

The Request of fast and comfortable travelling makes people rely more and moreon aircraft in21st century, under the high-altitude environment, air circulation in thecabin becomes the main indicators of quality assessment of flight comfort. The flowsof free jet coming from outlet turns into wall jet when it contacts with the human bodyand seat, airflow speed and fluctuation characteristics in the process have a closerelationship with the effect of the exchanges of the old and the new air, this flowphenomenon belongings to the scope of free Jet and impinging jet.Free Jet flow field contains a interaction of vortex boundary layer with externalflow field, and impinging Jet has some complex flow characteristics such as thestagnation and decay.These flow characteristics has brought great difficulties to theanalysis of flow field. So it requires extensive analysis to determine a more precisenumerical simulation of turbulent models when we study on Jet flow using numericalmethods.In the paper, based on the N-S equations, using different turbulence models forcalculating the jet, appropriate calculation models established under the experimentalconditions are using for predicting the mainstream velocity field、the intensity ofturbulent velocity、turbulence intensity and the distribution of the Nusselt number onthe impinging plane, then the forecast results are compared with the experimentaldata.In the paper, using the methods of RANS and LES for calculating the free jet andimpinging jet, and by comparing the result of the numerical simulation with theexperimental data coming from literature, it has been found that the results ofnumerical calculations are close with the experimental data overall, and has adeviation which can be accepted in some place of complex flow regions such asvortex boundary layer and the stagnation point in the core area. The numericalsimulation results are quite good meet with experimental results regardless of thetemperature factor,but the deviation of mainstream speed increases after taking intoaccount the temperature factor, but also there are some deviations of the Nusseltnumber of calculated and experimental values which measures the effects oftemperature and turbulence level. This indicates that the role of temperature factors is not ignored because it has an effect on heat transfer and the effect of turbulence pulsein10-20°temperature range; the deviation of heat transfer between the results ofnumerical simulations and experimental is small when the Reynolds number is greaterthan10,000, especially when the turbulence models take the enhanced type wallsurface function and thermal effects into account,but there is increasing deviation inthe areas of jet core under low Reynolds number; on different turbulence model, in jetof mainstream speed field, and pulse speed strength and wall surface heat transfer,area, the calculated results of two-equation turbulence models is more closer withexperimental values than the one-equation turbulence models of S-A、turbulencemodels of RSM and the methods of LES, and the standard k turbulence model ismore general than standard k turbulence model.The program provides a tool for the research of impinging jet in the actualcockpit environment, meanwhile getting advantages and disadvantages of differentturbulence models has some guiding significance to correct turbulence models.