LAUSR

Abstract The prediction of the on-ground risk caused by re-entering space debris requires accurate and computationally affordable models to compute wall heat flux and pressure coefficient  C p at every stage of the reentry. Such models already exist for the wind area of the debris, i.e the area directly impinged upon by fictitious lines parallel to the incoming flow. But the heat flux and  C p are often neglected in the shadow area, even though they can be relatively high for certain shapes of debris. The present work focuses on developing reduced order models for heat flux and  C p distributions in the shadow area of space debris, for hypersonic continuous flow conditions. We identified four phenomena which appear in the shadow area and cause relatively high levels of these aerodynamic quantities (attached flow, detached flow with fluid reattachment, detached flow with solid reattachment and shock–shock interactions). Models were developed for the heat flux and  C p distributions caused by attached flows on the lee side of cylindrical geometries using the Proper Orthogonal Decomposition (POD) and interpolation method. Using this method, it is possible to reduce the number of required data by efficiently exploring the parameters domain of variation. The sample points were chosen thanks to an adaptive design of experiments, and the input data for the models were obtained by 3D Navier–Stokes computations of the flow around cylinders at incidence. The analysis of the computational results highlighted the influence of the Reynolds number based on the cylinder diameter  R e D , ∞ on the heat flux and pressure distributions. Reduced-order models were created for three input parameters (length  L , diameter  D and angle of attack  α ) and fixed incoming flow conditions, using the POD and interpolation method, and then were extended to other upstream hypersonic continuous flow conditions by more classical approaches based on non-dimensional quantities. Finally, the reentry trajectories of two different cylindrical debris were computed with and without the new models developed, to demonstrate their influence on the integrated heat flux received by the debris during their reentry, and therefore on their survival rate.