Wind Tunnel Testing & Instrumentation

Subtopic: Subsonic & Supersonic Wind Tunnels

The vortex shedding frequency behind a landing gear model is found to be 50 Hz when tested in a wind tunnel operating at 5 m/s. If the actual landing gear size is 10 times that of the model, and it is designed to operate at 50 m/s, then the expected vortex shedding frequency behind it is ________ Hz (rounded off to the nearest integer).

Subtopic: Pitot-Static Probes & Pressure Transducers

Airplane A and Airplane B are cruising at altitudes of 2 km and 4 km, respectively. The free stream density and static pressure at altitude 2 km are 1.01 kg/m3 and 79.50 kPa, respectively, and at altitude 4 km, they are 0.82 kg/m3 and 61.70 kPa, respectively. The differential pressure reading from the pitot-static tubes is 3 kPa for both the airplanes. Assuming incompressible flow, the ratio of cruise speeds of Airplane A to Airplane B is ______. (round off to two decimal places)

Subtopic: Pitot-Static Probes & Pressure Transducers

An airplane of mass 4000 kg and wing reference area 25 m? flying at sea level has a maximum lift coefficient of 1.65. Assume density of air as 1.225 kg/m' and acceleration due to gravity as 9.8 m/s*. Using a factor of safety of 1.25 to account for additional unsteady lift during a sudden pull-up, the speed at which the airplane reaches a load factor of 3.2 is m/s (round off to two decimal places). A Pitot tube mounted on the wing tip of an airplane flying at an altitude of 3 km measures a pressure of 0.72 bar, and the outside air temperature is 268.66 K. Take the sea level conditions as, pressure = 1.01 bar, temperature = 288.16 K, and density = 1.225 kg/m'. The acceleration due to gravity is 9.8 m/s and the gas constant is 287 J/(kg K). Assuming standard atmosphere, the equivalent airspeed for this airplane is _ _ m/s (round off to two decimal place). Copyright: GATE 2020, IT Delhi

Subtopic: Subsonic & Supersonic Wind Tunnels

In a low -speed wind tunnel, t he angular location(s) from the front stagnation point on a circular cylinder where the static pressure equals the free-stream static pressure, is

Subtopic: Subsonic & Supersonic Wind Tunnels

An aircraft wind tunnel model, having a pitch axis mass moment of inertia (Iyy) of 0.014 kg-m^2, is mounted in such a manner that it has pure pitching motion about its centre of gravity, where it is supported through a frictionless hinge. If the pitching moment (M) derivative with respect to angle of attack ($\alpha$), denoted by 'M $\alpha

Subtopic: Subsonic & Supersonic Wind Tunnels

An aircraft wind tunnel model, having a pitch axis mass moment of inertia ($I_{yy}$) of 0.014 kg-m$^2$, is mounted in such a manner that it has pure pitching motion about its centre of gravity, where the aerodynamic pitching moment derivative with respect to pitch rate $C_{m_q} = -0.5$ rad$^{-1}$. The wind tunnel operates at a freestream dynamic pressure of $q_\infty = 1000$ N/m$^2$, velocity $V_\infty = 50$ m/s, wing area $S = 0.1$ m$^2$, and mean aerodynamic chord $\bar{c} = 0.1$ m. The damping ratio of the pitching oscillation is _________ (accurate to three decimal places).

Subtopic: Pitot-Static Probes & Pressure Transducers

A student can measure free-stream velocity of a low-speed wind tunnel using a i. Pitot tube alone aligned with the flow direction. ii. Pitot tube aligned with the flow direction with static pressure measurement at an appropriate position on the tunnel wall. iii. Pitot tube aligned with the flow direction along with barometer pressure reading of the outside ambient. iv. Pitot static tube alone aligned with the flow direction. Considering the above statements, which of the following options is correct?

Subtopic: Subsonic & Supersonic Wind Tunnels

A low speed wind tunnel has a contraction ratio of 14:1 and the cross-sectional area of the test section is 1 m^2. The static pressure difference between th e settling chamber and the test section is 40 cm of water column. Assume , and . The speed of air in the test section (in m/s) is 2m/s 81 . 9g 3kg/m^2 . 1air 3kg/m 1000water

Subtopic: Pitot-Static Probes & Pressure Transducers

A spacecraft of mass 100 kg, moving at an instantaneous speed of 1.8 x 10* m/s, picks up interstellar dust at the rate of 3.2 x 10-* kg/s. Assuming that the dust was initially al rest, the instantaneous rate of retardation of the spacecraft is: