Analysis of Boundary Layer Impact Transition Effects on Ballistic Reentry Vehicle Dispersion and Comparison with Other Dispersion Factors.

摘要

This paper analyzes the impact dispersion of a ballistic reentry vehicle caused by the transitory lift and drag components encountered during the brief altitude regime where the vehicle's boundary layer is changing from laminar to turbulent behavior. A simple physical model of the phenomenon is developed using adjustable parameters since the basic aerothermal materials physics is poorly understood. The adjustable parameters are identifiable with physical assumptions and one result is to focus attention on the nature of these assumptions in order to guide further theoretical and experimental work which can develop a better understanding of the phenomenon, particularly its impact on materials and structures technology. Under the assumptions made, numerical estimates are made of the boundary layer transition dispersion for a practical range of vehicle and trajectory parameters, and then compared with contributions from density, wind velocity, and drag variations and from the roll-through-zero effect. The boundary layer effects are found to be too large to be ignored and further studies are needed to bound the behavior. Additional studies of the Materials and Structures Technology Base Programs related reentry vehicle mission requirements will be made in a subsequent paper. (Author)