| Summary: | 碩士 === 國防大學理工學院 === 機械工程碩士班 === 100 === The purpose of this study is to utilize CFD method to discuss under different turbulence models(DES、k-ε、k-ω) the hypersonic flow across the optical dome with cooling jets, the flow fields associated with geometry derived from the aerodynamic characteristics, the distribution of surface temperature combined with viscous dissipation and radiation effect of aerodynamic heating. Under such flow, due to the friction, the viscous effect near wall causesd no-slip codition, much of kinetic energy diffused to heat energy, hence, its surface and surrounding gases responded to temperature arised. By the cooling technology, the window cooled down against the heating load, meanwhile, the cooling jets would cause complicated shock and shock, shock and boundary interaction to affect flow field surrounding the window, additionally, the strong turbulent fluctuation and sheared effect while cooling jets mixed in main flow may lead to more complex disturbing between the flow properties of velocity, pressure, temperature and dentity to affect the result of real temperature, so we need to discuss in this study.
The steady simulation of this study, the appropriate results of turbulence model compared to reference experimaental data of standoff distance validation is the k-ω. As thermal radiation effect introduced, the change of temperature at the stagnation point of nose would be 10.68% descent in DES turbulence model, 0.34% descent in k-ε model, and 6.31% in k-ω model. In order to make sure optical window temperature under 500K request, the optimum mass flow rate of cooling jets with dry air is 0.01kg/s. Further, under transient simulation without cooling, the during time of aerodynamic heating caused optical window’s surface temperature to reach critical temperature(500K) is 12 seconds for DES model, 10 seconds for k-ε model and 14 seconds for k-ω model.
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