A survey of selected investigations concerning drag associated with isolated or distributed roughness elements in laminar and turbulent flow is given. Basic roughness types tested in laboratory experiments are covered and the results are related to conditions on wings of subsonic aircraft. Whereas considerable information is available on zero-pressure-gradient two-dimensional turbulent flows with roughness effects can be incorporated in current routines for assessing overall drag of aircraft based on wind tunnel and flight tests is demonstrated. It is suggested to develop a computer code which will allow the determination of allowable roughness size, or the effect of given roughness size on drag for new aircraft. This program would also make possible predictions of the degradation in performance associated with maintenance procedures, structural modifications, etc. Such a program involves a detailed analysis of the flow field around wing and body instead of the over-simplified methods based on flat plate relations now in use.
A Survey of the Literature on Surface Roughness Effects on the Drag of Subsonic Aircraft
1978
131 pages
Report
Keine Angabe
Englisch