Question

Air at Ma 2.0 and p 10 psia is forced to turn through 10° by a ramp at the body surface. A weak oblique shock is formed. The 10° deflection resulted in a final Mach number of 1.641 and a pressure ratio of 1.707. When the flow is made to turn through 5, the final Mach number is slightly higher, and the final pressure is slightly lower. Ma2 Ma 2.0 P 10 lbf/in 10° True False O O

Answer 1

TRUE. As the angle of deflection (angle of ramp) is decreased from 10 degrees to 5 degrees, there is a lesser change in the velocity of air while it passes over the ramp. Most of the linear momentum of air is conserved thus, a even lower oblique shock is observed which results in a Mach number slightly higher than that obtained with the 10 degrees ramp. Following the Bernoulli's principle, the slightly lower Mach number (velocity) gives a slightly higher final pressure.