Similarity solutions of supercritical fluids laminar boundary layers with convective boundary conditions
In a scramjet engine,the high-temperature gas in the combustor and nozzle causes the fluid in the regenerative cooling channel to reach the supercritical state.This results in the formation of a supercritical flu-id boundary layer under convective boundary conditions,yet its fundamental theory remains unclear.To this end,the similarity solution was established to calculate the supercritical carbon dioxide(SCO2)flat-plat laminar boundary layers with convective boundary conditions.The free-stream pressure is 8 MPa.Thermal convection co-efficient Mθ and local convective heat transfer constant c were proposed in this paper.They are positively correlat-ed with the temperature and convective heat transfer coefficient of the hot fluid on the bottom surface of the plate,respectively.The effects of Mθ and c on velocity and temperature profiles are analyzed.When c is extremely small,the problem can be simplified to the adiabatic boundary condition.Conversely,when c is large enough,it exhibits behavior similar to an isothermal boundary condition.As Mθ and c increase,the wall heat flux also in-creases,leading to a transcritical regime if the free-stream temperature is subcritical.This exacerbates the de-crease in Nusselt number.
Supercritical fluidsConvective boundary conditionsLaminar boundary layerSimilarity solutionWall heat transfer
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