Boundary layer transition on reentry vehicle nosetips

Predicting reentry vehicle (RV) performance is a very difficult task and requires a detailed understanding of the nosetip boundary layer. Nosetip boundary layer transition typically occurs between 70,000 and 40,000 feet altitude and is a complex hypersonic fluid mechanics process that depends on surface roughness, wall temperature, nosetip geometry, and freestream conditions. The state of the boundary layer drives the ablation characteristics of the nosetip, which in turn, effects the vehicle performance. Therefore, accurate ground testing is vital in providing realistic RV preflight predictions. The current work analyzes the transition studies completed by many authors and makes recommendations on which author's correlation best fits wind tunnel, ballistic range, arc tunnel, and flight data. Using the best correlation, a new data set encompassing ballistic range and arc tunnel data is compared and correlated. A simplified correlation is suggested to reconcile some differences between the arc and range data sets. Furthermore, the study was enhanced by looking at the boundary layer problem using a linear stability model and a Reynolds number theoretical approach.