In turbojets with purely converging propelling nozzles, part of the thrust is also generated by the pressure difference:Group of answer choicesOnly when the flow is chokedBoth a and cWhether the flow is choked or notWhen the nozzle is operated overexpanded

The momentum thrust of a choked purely-converging nozzle of fixed area, fed by a reservoir of fixed composition and temperature:Group of answer choicesIncreases with increasing reservoir pressureRemains constant with decreasing backpressureAll of the aboveNone of the above

For a choked purely-converging nozzle fed by a reservoir of fixed composition and temperature, as the nozzle pressure ratio Pb/P0 is decreased, the mass flow rate through the nozzle:Group of answer choicesAlways increasesIncreases only if Pb is reducedIncreases only if P0 is increasedAlways constant

During the isentropic expansion of a flow in an ideal choked diverging nozzle:Group of answer choicesThe static pressure is decreasing as the velocity and Mach number decreasesThe static pressure remains constantThe total enthalpy and the static pressure are dropping as the Mach number increasesThe static pressure is decreasing as the velocity and Mach number increases

Distinguish between thrust and pressure.

A purely-converging nozzle is supplied by a reservoir of P0 = 100 bar and T0 = 300K, with the flow through the nozzle being adiabatic, reversible, and choked. Assume a constant 1 bar of back pressure (i.e exhausting into atmosphere). Answer the following questions:If the reservoir P0 is reduced assuming a constant T0, what effect will this have on the nozzle throat velocity AND mass flow rate? Explain why.If the reservoir pressure is allowed to reduce to say 1.2 bar, describe what effect (if any) this will have on the assumptions listed in the first sentence above.