Compressible Flow & Shocks

Subtopic: 1D Isentropic Flow & Area-Mach Relations

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

Subtopic: Normal & Oblique Shock Waves

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?

Subtopic: Normal & Oblique Shock Waves

Which of the following process(es) is/are involved in the compression of air in an ideal ramjet engine?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The figure below shows the velocity triangles at the inlet and outlet of the rotor of a low hub-to-tip ratio axial compressor at the mid-span of the blade. The absolute and relative velocities of the flow are denoted by C and W, respectively. The subscripts 1 and 2 refer to the locations before and after the rotor, respectively. The blade velocity is denoted by U. Select the CORRECT statement(s) for this device.

Subtopic: Prandtl-Meyer Expansion Waves

Consider a centered Prandtl-Meyer expansion fan at a $\theta$ = 4° 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

Subtopic: Rayleigh & Fanno Flow

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 ________ × 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 𝟒𝒇𝑳∗ 𝑫 × 𝟏𝟎𝟒 99.35 336.4 648.3 997.4 1361 1724

Subtopic: 1D Isentropic Flow & Area-Mach Relations

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

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A supersonic stream of an ideal gas at Mach number M1 = 5 is turned by a ramp, as shown in the figure. The ramp angle is 20o. The pressure ratio is p2 p1 = 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).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

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).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

On Day 1, an aircraft flies with a speed of V1 m/s at an altitude where the temperature is T1 K. On Day 2, the same aircraft flies with a speed of √1.2 V1 m/s at an altitude where the temperature is 1.2 T1 K. How does the Mach number M2 on Day 2 compare with the Mach number M1 on Day 1? Assume ideal gas behavior for air. Also assume the ratio of specific heats and molecular weight of air to be the same on both the days.

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Consider a steady, isentropic, supersonic flow (Mach number M > 1) entering a Convergent-Divergent (CD) duct as shown in the figure. Which one of the following options correctly describes the flow at the throat?

Subtopic: Normal & Oblique Shock Waves

Shock structures for flow at three different Mach numbers over a given wedge are shown in the figure below. Assuming that only the weak shock solutions are possible for the attached oblique shocks, which one of the following options is TRUE?

Subtopic: Prandtl-Meyer Expansion Waves

Air flowing at Mach number M = 2 from left to right accelerates to M = 3 across an expansion corner as shown in the figure. What is the value of $\delta$ (the angle between the Forward and Rearward Mach lines) in degrees? The values of the Prandtl-Meyer functions are $\nu$(3) = 49.76o and $\nu$(2) = 26.38o.

Subtopic: Rayleigh & Fanno Flow

Consider the following Fanno flow problem: Flow enters a constant area duct at a temperature of 273 K and a Mach number 0.2 and eventually reaches sonic condition (Mach number =1) due to friction. Assume $\gamma$ = 1.4. The static temperature at the location where sonic condition is reached is_____________ K (rounded off to 2 decimal places).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

For an aircraft moving at 4 km altitude above mean sea level at a Mach number of 0.2, the ratio of equivalent air speed to true air speed is _______ ( rounded off to 2 decimal places). The density of air at mean sea level is 1.225 kg/m3 and at 4 km altitude is 0.819 kg/m^3.

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The ratio of the speed of sound in H^2 (molecular weight 2 kg/kmol) to that in N^2 (molecular weight 28 kg/kmol) at temperature 300 K and pressure 2 bar is ____. (round off to two decimal places)

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A supersonic vehicle powered by a ramjet engine is cruising at a speed of 1000 m/s. The ramjet engine burns hydrogen in a subsonic combustor to produce thrust. The heat of combustion for hydrogen is 120 MJ/kg. The overall efficiency of the engine o , defined as the ratio of propulsive power to the total heat release in the combustor, is 40%. Taking acceleration due to gravity 0 10g = m/s^2, the specific impulse of the engine is _____________ seconds. (round off to the nearest integer).

Subtopic: Normal & Oblique Shock Waves

A supersonic aircraft has an air intake ramp that can be rotated about the leading edge O such that the shock from the leading edge meets the cowl lip as shown in the figure. Select all the correct statement(s) as per oblique shock theory when the flight Mach number M is increased.

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A perfect gas stored in a large reservoir exhausts into the atmosphere through a convergent duct. The reservoir pressure is P0 and temperature is T0. The jet emerges from 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

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A scramjet engine features an intake, isolator, combustor, and a nozzle, as shown in the schematic. Station 3 indicates the combustor entry point. Assume stagnation enthalpy to be constant between Stations 1 and 3, and air to be a calorically perfect gas with specific heat ratio $\gamma$. Select the correct expression for Mach number M3 at the inlet to the combustor from the options given.

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Consider a one-dimensional inviscid supersonic flow in a diverging duct with heat addition (Qin) as shown. Which of the following statement(s) is/are always TRUE?

Subtopic: Normal & Oblique Shock Waves

The point of maximum entropy on a Fanno-curve in a Temperature-Entropy (T-s) diagram represents the

Subtopic: Normal & Oblique Shock Waves

Across an oblique shock wave in a calorifically perfect gas,

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A convergent nozzle fed from a constant pressure, constant temperature reservoir, is discharging air to atmosphere at 1 bar (absolute) with choked flow at the exit (marked as Q). Flow through the nozzle can be assumed to be isentropic. If the exit area of the nozzle is increased while all the reservoir parameters and ambient conditions remain the same, then at steady state

Subtopic: 1D Isentropic Flow & Area-Mach Relations

In a converging duct, area and velocity at section P are 1 m 2 and 15 m/s, respectively. The temperature of the fluid is 300 K. Air flow through the nozzle can be assumed to be inviscid and isothermal. Characteristic gas constant is 287 J/(kg-K) and ratio of specific heats is for air. To ensure that the air flow remains incompressible (Mach number, M ≤ 0.3) in the duct, the minimum area required at section Q is _____ m^2 (rounded off to two decimal places).

Subtopic: Normal & Oblique Shock Waves

In a converging-diverging nozzle, Nozzle A displays oblique shock waves at the exit plane, whereas Nozzle B displays an expansion fan at the exit plane. Nozzles A and B, respectively, are operating in:

Subtopic: Rayleigh & Fanno Flow

An ideal gas flows steadily through a constant area duct with friction (Fanno flow). As the flow proceeds downstream towards the choking point, the stagnation temperature $T_0$:

Subtopic: 1D Isentropic Flow & Area-Mach Relations

How does the propulsive efficiency of a turbofan engine, operating at a given cruise altitude and Mach number, vary with bypass ratio (BPR)?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Q.29 The figure shows schematic of a set-up for visualization of non-uniform density field in the test section of a supersonic wind tunnel. This technique of visualization of high speed flows is known as: • Tunnel wall

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Normal & Oblique Shock Waves), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Rayleigh & Fanno Flow), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Which of the following operations will result in an increase in the Mach number of a supersonic flow in a constant-area duct?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

In an aerospace engineering analysis of Inlets, Combustors & Nozzles (Subsonic & Supersonic Inlets), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Normal & Oblique Shock Waves), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Rayleigh & Fanno Flow), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The design flight Mach number of an ideal ramjet engine is 2.8. The stagnation temperature of air at the exit of the combustor is 2400 K. Assuming the specific heat ratio of 1.4 and gas constant of 287 J/(kg K), the velocity of air at the exit of the engine is m/s (round off to one decimal place).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

For a quasi-one-dimensional isentropic supersonic flow through a diverging duct, which of the following is true in the direction of the flow?

Subtopic: Normal & Oblique Shock Waves

01 (see Figure 1). The resulting oblique shock with shock angle ß is then reflected from the top wall. For the reflected shock, the turn angle is 02 and the shock angle is Bz. increasing M M2 Figure 1 Figure 2 Use the weak shock solution from the e-ß-M plot shown in Figure 2 to choose the correct option from the following.

Subtopic: Normal & Oblique Shock Waves

A supersonic flow in a constant area duct at Mach number $M_1$ encounters a compression ramp of angle $\theta_1$ generating an oblique shock wave. Which of the following statements is TRUE across the shock wave?

Subtopic: Normal & Oblique Shock Waves

The static pressure ratio across a stationary normal shock is given by $\frac{P_2}{P_1} = 1 + \frac{2\gamma}{\gamma + 1}(M_1^2 - 1)$, where $M_1$ is the upstream Mach number and $\gamma = 1.4$. If the static pressure ratio across the shock is $\frac{P_2}{P_1} = 29.0$, the upstream Mach number $M_1$ is _________ (round off to 2 decimal places).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A thermocouple, mounted flush in an insulated flat surface in a supersonic laminar flow of air measures the

Subtopic: Normal & Oblique Shock Waves

A shock wave is moving into still air in a shock tube. Which one of the following happens to the air?

Subtopic: Normal & Oblique Shock Waves

The first law of thermodynamics is also known as conservation of

Subtopic: Normal & Oblique Shock Waves

A convergent-divergent nozzle is operated at a pressure ratio such that an oblique shock wave is attached to the exit lip outside the nozzle. This nozzle is operating in:

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Air at 50 kPa pressure and 400 K temperature flows in a duct at Mach 3.0. A part of the flow leaks through an opening on the duct wall into the ambient, where the pressure is 30 kPa. The maximum Mach number achieved in the discharge is _______ (accurate to two decimal places). (Ratio of specific heats of air is $\gamma$ = 1.4). 8/9

Subtopic: Normal & Oblique Shock Waves

Consider a 20 0 half-angle wedge in a supersonic flow at Mach 3 .0 at standard sea -level conditions. If the shock-wave angle on the wedge is 360, the Mach number of the tangential component of the flow post-shock is _______ (accurate to two decimal places).

Subtopic: Normal & Oblique Shock Waves

Consider a $20^\circ$ half-angle wedge in a supersonic flow at Mach 3.0 at standard sea-level conditions. If the shock-wave angle on the wedge is $36^\circ$, the Mach number of the tangential component of the flow downstream of the shock wave is _________ (accurate to two decimal places).

Subtopic: Normal & Oblique Shock Waves

A strong normal shock wave, with a pressure ratio of 29 across it, is traveling into still air ($T_1 = 300$ K, $\gamma = 1.4$). The Mach number of the shock wave is _________ (round off to 2 decimal places).

Subtopic: Normal & Oblique Shock Waves

For a given chamber pressure, the thrust of a rocket engine is highest when

Subtopic: Normal & Oblique Shock Waves

A planetary probe is launched at a speed of 200 km/s and at a distance of 71,400 km from the mass center of its nearest planet of mass 1.9 × 1028 kg. The universal gravitational constant, C— 667 × 10-11 m3 kg s?. The ensuing path of the probe would be

Subtopic: Normal & Oblique Shock Waves

- on the suction side and as sin e (1 + cos 0)or -V.. sin 0 on the pressure side, where @ corresponds to the chordwise position, x=≤(1- cost). Then tz-t, is 8лас

Subtopic: 1D Isentropic Flow & Area-Mach Relations

An aerospace system operating under standard sea level conditions is governed by Inlets, Combustors & Nozzles (Subsonic & Supersonic Inlets). Compute the required parameter in standard SI units (rounded off to the acceptable range).

Subtopic: Normal & Oblique Shock Waves

An aerospace system operating under standard sea level conditions is governed by Compressible Flow & Shocks (Normal & Oblique Shock Waves). Compute the required parameter in standard SI units (rounded off to the acceptable range).

Subtopic: Normal & Oblique Shock Waves

An aerospace system operating under standard sea level conditions is governed by Compressible Flow & Shocks (Rayleigh & Fanno Flow). Compute the required parameter in standard SI units (rounded off to the acceptable range).

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Match the appropriate engine (in right column) with the corresponding aircraft (in left column) for most efficient performance of the engine. a. Low speed transport aircraft i. Ramjet b. High subsonic civilian aircraft ii. Turboprop c. Supersonic fighter aircraft iii. Turbojet d. Hypersonic aircraft iv. Turbofan

Subtopic: Normal & Oblique Shock Waves

A student needs to find velocity across a stationary normal shock. He measures density and pressure across the shock as shown in the figure below. 1bar = 105Pa. (No shock table is needed for the calculations). The value of u1 in m/s is ____.

Subtopic: Prandtl-Meyer Expansion Waves

Which one of the following statements is NOT TRUE for a supersonic flow?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The critical Mach number for a flat plate of zero thickness, at zero angle of attack, is _________

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Consider one-dimensional isentropic flow at a Mach number of 0.5. If the area of cross-section of a streamtube increases by 3% somewhere along the flow, the corresponding percentage change in density is ________

Subtopic: Prandtl-Meyer Expansion Waves

Consider a supersonic stream at a Mach number M=2, undergoing a gradual expansion. The stream is turned by an angle of 3 degrees due to the expansion. The following data is given. M  (Prandtl-Meyer function) 1.8 20.73 1.9 23.59 2.0 26.38 2.1 29.10 2.2 31.73 2.3 34.28 2.4 36.75 The Mach number downstream of the expansion is (A) 1.88 (B) 2.00 (C ) 2.11 (D) 2.33 1 2 3 4 5 6 2013 AEROSPACE ENGINEERING - AE AE 13/19

Subtopic: 1D Isentropic Flow & Area-Mach Relations

For which one of the nozzle exit Mach numbers given below is the propulsive efficiency highest?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

For which one of the nozzle exit Mach numbers given below is the thrust highest?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The Mach angle for a flow at Mach 2.0 is

Subtopic: Normal & Oblique Shock Waves

An oblique shock wave with a wave angle $\beta$ is generated from a wedge angle of $\theta$ . The ratio of the Mach number downstream of the shock to its normal component is

Subtopic: Normal & Oblique Shock Waves

In a closed-circuit supersonic wind tunnel, the c onvergent-divergent (C-D) nozzle and test section are followed by a C-D diffuser to swallow the starting shock. Here, we should have the

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (1D Isentropic Flow & Area-Mach Relations), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

A turbojet powered aircraft is flying at Mach nu mber 0.8 at an altitude of 10 km. The inlet and exit areas of the engine are 0.7 m 2 and 0.4 m 2 respectively. The exhaust gases have velocity of 500 m/s and pressure of 60 kPa. The free stream pressure , density and speed of sound are 26.5 kPa, 0.413 kg/m3 and 299.5 m/s respectively. The thrust of the engine (in kN) is

Subtopic: 1D Isentropic Flow & Area-Mach Relations

4 (2 ) te t (D) 2 1 52( 2 2 )tet t  2011 AEROSPACE ENGINEERING - AE A jet engine is operating at a Mach number of 0.8 at an altitude of 10 km. The efficiency of the air intake is 0.8 and that of the compressor is 0.87. Th e total temperatures (in K) at the exits of the air intake and the compressor respectively are (Ambient pressure = 26.5 kPa; Ambient temperature = 223.3 K; Gas constant,  = 1.4; 8rcp )

Subtopic: Normal & Oblique Shock Waves

A normal shock wave in an ideal gas flow:

Subtopic: 1D Isentropic Flow & Area-Mach Relations

The speed of sound in an ideal gas is proportional to:

Subtopic: 1D Isentropic Flow & Area-Mach Relations

In a convergent-divergent nozzle operating at design conditions, the Mach number at the throat is:

Subtopic: Normal & Oblique Shock Waves

Consider the inviscid, adiabatic flow of air at free stream conditions M_inf = 2. A wedge of half-angle 10 degrees is placed in the flow. The shock attached to the wedge apex is an:

Subtopic: Normal & Oblique Shock Waves

For a flow across an oblique shock which of the following statements is true?

Subtopic: Normal & Oblique Shock Waves

The question below consists of a pair of related words followed by four pairs of words. Select the pair that best expresses the relation in the original pair: Unemployed : Worker

Subtopic: Normal & Oblique Shock Waves

His rather casual remarks on politics _ his lack of seriousness about the subject.

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Normal & Oblique Shock Waves), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: Normal & Oblique Shock Waves

In an aerospace engineering analysis of Compressible Flow & Shocks (Rayleigh & Fanno Flow), which one of the following statements is CORRECT regarding the governing aerodynamic and structural behavior?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Mach number at the entry to the combustion chamber is around

Subtopic: Normal & Oblique Shock Waves

The static pressure along the nozzle downstream of the normal shock

Subtopic: 1D Isentropic Flow & Area-Mach Relations

If the flow Mach number in a turbulent boundary layer over a flat plate is increased keeping the Reynolds number unchanged, the skin friction coefficient Cr

Subtopic: Normal & Oblique Shock Waves

In supersonic wind-tunnel design, an oblique shock diffuser is preferred over a normal shock diffuser because

Subtopic: Normal & Oblique Shock Waves

M. will cause the oblique shock wave to

Subtopic: Normal & Oblique Shock Waves

Which one of the following high lift device results in higher stalling angle?

Subtopic: 1D Isentropic Flow & Area-Mach Relations

An aircraft is cruising at a Mach number of 0.8 at an altitude where the ambient static pressure is 95 kPa. The diffuser exit total pressure is 140 kPa. Assuming there is no change in the specific heat at constant pressure across the diffuser, and ratio of specific heats is 1.4, the adiabatic efficiency of the intake is

Subtopic: Normal & Oblique Shock Waves

Across a normal shock

Subtopic: 1D Isentropic Flow & Area-Mach Relations

Wing A has a constant chord c and span b. Wing B is identical but has a span 4b. When both wings are operating at the same geometric angle of attack at subsonic speed, then:

Subtopic: Prandtl-Meyer Expansion Waves

The flow system shown is designed such that the expansion generated at A is completely absorbed by wall B for p_1 = p_d. For p_1 > p_d, which of the following statements is NOT true?