Engineering

Aerospace engineering

Laminar flow

Materials science

Mach number

Aerodynamics

Flow separation

Boundary layer

Physics

Flow (mathematics)

Transonic

Fuselage

Mechanics

Adverse pressure gradient

This paper discusses research variables that directly impact the ability to obtain laminar flow and techniques to reduce flow separation. Laminar flow control has long been considered as a potentially viable technique for increasing aircraft performance. Previous studies have demonstrated that laminar flow control could reduce takeoff total weight, mission fuel, and structural temperatures. This paper will show flow over fuselage using active and passive designs. Active design uses a porous boundary condition, whereas, passive design without a porous boundary condition. A primary goal of the passive design is to obtain detailed surface pressure-distribution data. These data were obtained for a Mach range of 0.4 - 0.9. This paper demonstrated that laminar flow and flow separation-reduction can be achieved on a blunt fuselage configuration for a Mach range of 0.4 - 0.9. Pressure-distribution and transition data were obtained for a Mach range of 0.4 - 0.9. The results show that large regions of laminar flow can be achieved when active laminar flow control is used. This paper shows that slower moving air on the upper surface can be increased in speed by bringing air from the high pressure area on the bottom of the fuselage through slots. One can conclude from this study, also that the porous boundary condition should be at least 2/3 of the incoming free stream velocity and in the axial direction. Pressure will decrease on the top so the adverse pressure gradient which would cause the boundary layer separation reduces.

Reduction of Flow Separation from a Fuselage for Subsonic and Transonic Flows