Method Of Data Correlation For Hypersonic Viscous Interaction Effect

Hypersonic viscous interaction effects markably affect the aerodynamic characteristics,such as surface-pressure distribution and skin friction over models or vehicles.Limited by the operational characteristics and simulated capability of hypersonic wind tunnels,it is difficult to simulate aerodynamic characteristics under the effects of viscous interaction phenomenon solely by experiments.Correlative parameters are commonly used to extrapolate experimental results to flight conditions."Experimental results,flight data and correlative parameter are three elements for data correlation,and the correlative parameter is the crucial one".Theoretical method,experiments in wind tunnels and numerical simulation are applied to research on data correlation of hypersonic viscous interaction effects for lift body.Results and conclusions are briefly given as follows:(1)General estimated method of uncertainty is established for hypersonic wind tunnels,hypersonic low-density tunnels and shock tunnels.The estimated method for aerodynamic experiments offers an effective mean to improve the quality of experimental results.(2)For hypersonic aerodynamic experiments,scaling method is applied to standardize governing equations to obtain similarity parameters,one of which is regarded as fundamental form of correlative parameter for viscous interaction effect.The meaning of similarity parameters in scaling equations are analyzed theoretically,and the specifc flight conditions are combined with scaling equations to evaluate each similarity parameter's influence for hypersonic flow.(3)On the basis of theoretical results of scaling equations,the item of the loss of mechanical energy by viscosity in governing equations denotes the hypersonic viscous interaction phenomenon.The fundamental form of correlative parameter is proposed for viscous interaction effects,and the parameter embodies the essence of viscous interaction effect-"interaction between boundary layer and inviscid flow".Furthermore,the fundamental form of correlative parameter is validated by experimental and numerical results of lift body and cone-model.Most of correlative parameters for viscous interaction effects which are effective in data correlation are of the format of fundamental form,and these parameters are developed on the basis of massive experimental results from different wind tunnels.The proposal of fundamental form for viscous interacion effects offers theoretical support for these correlative parameters.(4)A joint correlative parameter is proposed to correlate experimental data with flight data for lift body.On the basis of experimental and numerical results of lift body,correlative results between joint correlative parameter with axial force coefficient are improved efficiently compared with other parameters in terms of precision and accuracy.Furthermore,issues on applicability of correlative method to various aerodynamic configurations are discussed under the effect of viscous interaction phenomenon.