EXPERIMENTAL STUDY OF CHARACTERISTICS OF MICRO-HOLE POROUS SKINS FOR TURBULENT SKIN FRICTION REDUCTION

摘要

Characteristics of micro-hole porous skins forrnthe turbulent skin friction reduction technologyrncalled the micro-blowing technique (MBT) werernassessed experimentally at Mach 0.4 and blowingrnfractions from zero to 0.005. The objectivernof this study was to provide guidelines for thernselection of porous plates for MBT. The holernangle, pattern, diameter, aspect ratio, and porosityrnwere the parameters considered for thisrnstudy. The additional effort to angle and staggerrnthe holes was experimentally determined to bernunwarranted in terms of skin friction benefit;rntherefore, these parameters were systematicallyrneliminated from the parametric study. Thernimpact of the remaining three parameters wasrnevaluated by fixing two parameters at thernreference values while varying the third parameter.rnThe best hole-diameter Reynolds numberrnwas found to be around 400, with an optimumrnaspect ratio of about 6. The optimum porosityrnwas not conclusively discerned because thernrange of porosities in the test plates consideredrnwas not great enough. However, the porosityrnwas estimated to be about 15 percent or less.