DETERMINATION OF FREE-MOLECULAR DRAG FOR A FLAT PLATE WITH A NORMAL PROTUBERANCE INCLUDING MULTIPLE SURFACE COLLISIONS.
Abstract
The normal and shear forces are determined and the total drag is predicted for free-molecular flow over a two-dimensional flat plate with a normal protuberance emphasizing the effects of multiple surface collisions. The plate is aligned parallel to the flow and the protuberance is of infinitesimal thickness. A complete analysis is presented which includes all components of thermal motion. The gas particles are assumed to be diffusely reflected from the surfaces and completely accommodated to the wall temperature. The number densities required for the surface distribution functions are found by solving coupled Fredholm integral equations of the second kind using the collocation method. The contributions of the various components of drag are compared and several approximate methods for predicting the drag are presented. Finally, it is demonstrated that for large speed ratios the freestream contributions to the stresses and flux at the surfaces can be predicted quite well by neglecting the thermal motion of the particles in the freestream direction. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 27, 1967
- Accession Number
- AD0667218
Entities
People
- J. D. Stewart
Organizations
- The Aerospace Corporation