Compressible flows - Aerodynamics - Aerospace Engineering Previous Year Questions

In a fluid flow, Mach number is an estimate of _____.

An aircraft is flying at an altitude of 4500 m above sea level, where the ambient pressure, temperature and density are 57 kPa, 259 K and 0.777 kg/m³, respectively. The speed of the aircraft (V) is 230 m/s. Gas constant R= 287 J/kg/K, and specific heat ratio \(\gamma = 1.4\). If the stagnation pressure is \(p_0\), and static pressure is \(p\), the value of \(\left[\frac{p_0 - p}{\frac{1}{2} \rho V^2}\right]\) is ____ (rounded off to two decimal places).

A supersonic stream of an ideal gas at Mach number \(M_1 = 5\) is turned by a ramp, as shown in the figure. The ramp angle is 20°. The pressure ratio is \(\frac{p_2}{p_1} = 7.125\) and the specific heat ratio is \(\gamma = 1.4\). The pressure coefficient on the ramp surface is ________ (rounded off to two decimal places).

The mass flow rate in a supersonic wind tunnel is 2 kg/s when the stagnation pressure and stagnation temperature are 1 MPa and 800 K, respectively. If the stagnation pressure and stagnation temperature are changed to 3 MPa and 200 K, the mass flow rate in the tunnel changes to ________ kg/s (answer in integer).

In the figure shown below, the flow at the nozzle exit is ______.

Which of the following statements is/are TRUE regarding critical and drag divergence Mach numbers of a wing?

A flow is steady, inviscid and one-dimensional, with no shaft work or body forces. Which of the following is/are possible under the given conditions?

Consider a centered Prandtl-Meyer expansion fan at a \(\theta = 4^\circ\) corner in a Mach 1.78 air flow, as shown in the figure below. The angle \(\psi\) (see figure) made by the ending wave of the fan with respect to the incoming stream is __________ degrees (rounded off to 1 decimal place).
An excerpt from the table of Prandtl-Meyer function for air is provided below.

\(M\)	\(\nu\) [deg]	\(M\)	\(\nu\) [deg]	\(M\)	\(\nu\) [deg]
1.72	18.40	1.82	21.30	1.92	24.15
1.74	18.98	1.84	21.88	1.94	24.71
1.76	19.56	1.86	22.45	1.96	25.27
1.78	20.15	1.88	23.02	1.98	25.83
1.80	20.73	1.90	23.59	2.00	26.38

A Mach 1.5 air flow enters a round duct of length 20 cm and diameter 3 cm. If the flow exits with Mach number 1.1, the average Fanning friction factor \(f\) of the duct is __________ \(\times 10^{-3}\) (rounded off to 1 decimal place).
An excerpt from the Fanno flow table for air is given below.

\(M\)	1.1	1.2	1.3	1.4	1.5	1.6
\(\frac{4fL^*}{D} \times 10^4\)	99.35	336.4	648.3	997.4	1361	1724