Reduction of V/STOL Downwash Effects by Jet Exhuast Flow Control.

摘要

The performance of V/STOL aircraft is influenced significantly by ground effects during landing and takeoff when the propulsive flow of the aircraft is directly dowward. To mitigate downwash effects, a new landing mat concept was developed at Civil Engineering Laboratory whereby exhaust flow is controlled by either a very thin array of diamond patterns or parallel ribs. The impinging jet flow aligns itself with the long axis of the grid pattern, expanding in two directions along a single line rather than radially outward over the plane of the ground. Grid height or thickness is small compared with jet diameter. A method for calculating grid height was developed by combining Froessling's solution for boundary layer thickness and Glauert's solution for wall jet thickness. (Author)