flow rate in the case of subsonic and supersonic flow ( CD NOZZLE)
Hi every body :
Are you ok with me that in the absence of leakage , also in the case of isentropic flow ( no friction , no drop in total pressure etc.) the mass flow rate is constant between inlet and outlet ? that means : Ae me (dot) =As ms (dot)?
My problem : i have found in a book what follows : (it is not clear for me )
1/ after a shock in the throat , the flow becomes subsonic , it is isentropic so the Mach number at the exit of the divergent remains the same as the Mach calculated before the shock .
my question is why ? is this conclusion was deduced from the mass flow conservation ? I don't see the physics behind it .
Remark : M=cte that means A/Ac=cte
2/ We have a shock at the divergent and the flow is considered sonic at the throat .We can so suppose that the flow rate at the outlet is the same ( as this found before the shock ) !
It is not clear ! At my opinion , the shock is irreversible so the flow rate can not be the same as we have a shock in the divergent ! Conclusion : it is not possible to consider ( in the presence of a shock) the same flow rate (found before the shock)
Can you help me please !
(sorry for english mistakes 😊)