Radiation shape factors between end plane and outer wall of concentric tubular enclosures

Abstract

The boundary-layer velocity profiles at the trailing edge of the model for the three levels of pressure fluctuations are shown in Fig. 4. There is a considerable change in the velocity profiles when the levels of p/q were changed from .006 to .011. The changes, with further increases in p/q, are not noticeable. Figure 5 shows the turbulence profiles at the trailing edge for the three levels of p/q. A typical turbulence profile obtained in an attached turbulent boundary layer at zero pressure gradient is also shown for comparison. The levels of turbulence in the separated layer are generally an order higher than those in an attached boundary layer. The levels are sensitive to the changes in p/q. With the increase in pressure fluctuation levels, the turbulence initially increases and then decreases. However, the changes in the freestream turbulence levels are insignificant for all levels of p/q remaining constant at about 2.4% The general effect of pressure fluctuations on the shock/boundary-layer interaction is shown schematically in Fig. 6. It is suggested that there is virtually no effect of pressure fluctuations up to a level of about 0.6%. With the increase in pressure fluctuations, whether the effect beyond this level is gradual or sudden is uncertain and needs further investigation.