I mean, for a turbofan: $$ T= \dot m_{air,h} (1+f) v_{e,h}+ \dot m_{air,c} v_{e,c}- (\dot m_{air,h}+ \dot m_{air,c} ) v_0+ (P_{e,h}-P_{amb} ) A_{e,h}+ (P_{e,c}-P_{amb} ) A_{e,c} $$
but $$ \dot m_{air}=\rho Av_0 $$
do I have to impose $\dot m_{air}$? in this case how the thrust expression change (in particular the terms with $v_0$)?