Question

The stagnation pressure for a compressible flow can be accurately described as (check all that apply):
A. The pressure the flow would reach if brought to rest adiabatically.
B. The pressure the flow would reach if brought to rest isentropically.
C. The pressure the flow would reach if brought to rest isothermally.
D. The pressure the flow would reach if accelerated to Mach 1 adiabatically.
E. The pressure the flow would reach if accelerated to Mach 1 isentropically.
F. The pressure the flow would reach if accelerated to Mach 1 isothermally.
G. The highest pressure that the flow can reach without work or heat transfer.
H. The current, local pressure in the flow.
I. The pressure measured by a pressure sensor at the front of a sphere in a subsonic compressible flow, neglecting viscous effects.

Answer 1

"A) [stagnation pressure the flow would reach if brought to rest isentropically.] c_p T_0 = c_p T + v^2/2 h_0 = h_1 + v_1^2/2 stagnation enthalpy stagnation P_0/P = (T_0/T)^k/k - 1 stagnation isentropic > stagnation actual E) The pressure the flow would reach if accelerated to mach 1 isentropically is called the "" critical pressure "" not stagnation pressure. when Ma = 1 P*/P_0 = critical/stagnation = (2/k + 1)^k/k - 1"