Numerical analysis of simulation accuracy for hypersonic heat transfer in subsonic jets of dissociated nitrogen

Abstract

One-dimensional problems of the flow in a boundary layer of finite thickness on the end face of a model and in a thin viscous shock layer on a sphere are solved numerically for three regimes of subsonic flow past a model with a flat blunt face exposed to subsonic jets of pure dissociated nitrogen in an induction plasmatron [1] (for stagnation pressures of (104–3·104) N/m2 and an enthalpy of 2.1·107 m2/sec2) and three regimes of hypersonic flow past spheres with parameters related by the local heat transfer simulation conditions [2, 3]. It is established that given equality of the stagnation pressures, enthalpies and velocity gradients on the outer edges of the boundary layers at the stagnation points on the sphere and the model, for a model of radius Rm=1.5·10−2 m in a subsonic jet the accuracy of reproduction of the heat transfer to the highly catalytic surface of a sphere in a uniform hypersonic flow is about 3%. For surfaces with a low level of catalytic activity the accuracy of simulation of the nonequilibrium heat transfer is determined by the deviations of the temperatures at the outer edges of the boundary layers on the body and the model. For this case the simulation conditions have the form: dU∘e/dx∘=idem, p0=idem, Te=idem. At stagnation pressuresP0≥2·104N/m2 irrespective of the catalycity of the surface the heat flux at the stagnation point and the structure of the boundary layer near the axis of symmetry of models with a flat blunt face of radius Rm≥1.5·10−2 m exposed to subsonic nitrogen jets in a plasmatron with a discharge channel radius Rc=3·10−2 m correspond closely to the case of spheres in hypersonic flows with parameters determined by the simulation conditions [2, 3].