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

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

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

A perfect gas stored in a large reservoir exhausts into the atmosphere through aconvergent duct. The reservoir pressure is P0 and temperature is T0. The jet emergesfrom the nozzle at choked conditions with average velocity u, Mach number M,pressure p, temperature T, and density . If the reservoir pressure is increased,then(A) u, M, p, T, and increase(B) u, p, T, and increase, but M remains the same(C) u, M, and T remain the same, but p and increase(D) u, M, T and remain the same, but p increasesQ.40 Consider a general aviation airplane with weight 10 kN and a wing planform areaof 15 m2. The drag coefficient of the airplane is given as02D D LC C KC= + with0 0.025DC =and0.05K = . For level flight at an altitude where the density is0.60 kg/m3 and thrust 1 kN, the maximum cruise speed is(rounded off to the nearest integer)(A) 87 m/s(B) 30 m/s(C) 36 m/s(D) 101 m/s

For an adiabatic and reversible, converging-diverging nozzle, operating in vacuum:Group of answer choicesSpecific thrust always increases with increasing area ratioSpecific thrust is maximised at a particular, finite area ratioA purely-converging nozzle will produce the same thrust as a converging-diverging nozzle, irrespective of area ratioThe Mach number at the throat will be moderately supersonic