A REVIEW OF BINARY BOUNDARY LAYER CHARACTERISTICS
RAND CORP SANTA MONICA CA
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For several years RAND has investigated means of applying principles of mass-transfer and ablation cooling to problems of atmospheric reentry and to the design of efficient hypersonic flight vehicles. In connection with ablation cooling, this research memorandum examines the binary boundary layer problem. The study should make possible more rapid and reliable estimates of surface cooling methods for use with hypersonic vehicles such as intercontinental ballistic missile nose cones. A binary boundary layer is one in which some foreign substance has been injected to alter the properties of the flow, notably its heat transfer characteristics. Several methods available for accomplishing this injection, or mass transfer, are the transpiration of gas through slots, and the ablation or sloughing away of surface particles. The mechanism of laminar binary boundary layer flow is discussed in mathematical terms, and five different analyses involving a variety of injected substances are reviewed. Generalized expressions are then developed for predicting heat transfer and skin friction performance in the presence of mass transfer cooling for laminar flow over a flat plate. The results indicate that different foreign materials for example, hydrogen, carbon dioxide, and iodine vapor injected into the boundary layer stream reduce heat transfer and skin friction coefficients by an amount which depends on the molecular weight of the injected material. In conclusion, mass transfer cooling in a turbulent boundary layer and sublimation cooling are considered.
- Fluid Mechanics