Experimental Aerodynamics Mid - I, September - 2014

1.First photographic record of aerodynamic flight was obtained by
  • Otto Lilienthal
  • Wright brothers
  • George Cayley
  • Perci Pitcher
Answer: A
2.A blow down supersonic tunnel requires an intake drier to prevent _________ in the test section.
  • ionization
  • Condensation
  • vaporization
  • cooling
Answer: B
3.The object of vanes is to apply a force on the flow perpendicular to the ______
  • Stream function
  • adverse gradient
  • free stream
  • pressure gradient
Answer: A
4.Fans develop their highest efficiency when in a relatively _____
  • low speed flow
  • high speed flow
  • transonic flow
  • hypersonic flow
Answer: B
5.Buoyancy artificially increases the _________
  • Lift
  • drag
  • thrust
  • weight
Answer: B
6.Streamline curvature effect in wind tunnel boundary connection is accounted for by a series of mirror images of a
  • Uniform flow
  • Doublets
  • vortex
  • both a & b
Answer: C
7.Path lines, streak lines & streamlines coincide when the flow is
  • nearly inviscid
  • turbulent
  • unsteady & laminar
  • steady & laminar
Answer: B
8.In a closed duct this means that the airspeed outside the wake must be V for a constant mass flow rate.
  • Smaller than
  • equal to
  • larger than
  • both a & c
Answer: C
9.In a shock tunnel high pressure region and low region is separated by a ___________ which burst and causes a shock
  • insulator
  • Wring
  • Sheet of balsa
  • Diaphram
Answer: D
10.For the first time _____________ used wind tunnel for testing the airfoil sections.
  • otto lilienthal
  • wright brothers
  • George summon
  • goddard
Answer: B
11.____________has is used a whirling Arm to measure the drag & lift on airfoils, the first successful unmanned glider in 1804.
Answer: George Cayley
12.In a spin test tunnel the velocity profile has a _____________gradient.
Answer: Dish shaped
13.The _____________must be between 0.8 and 0.9 of the wind tunnel’s width, leading to a width of around 3 mts.
Answer: Span
14.In a diffuser ____________decreases with in increase______________, causing an adverse pressure gradient .
Answer: Airspeed , static pressure
15.The corner loss coefficient is defined as________________________.
Answer: Efficiency= delta[p]/dynamic pressure
16.The longitudinal pressure gradient is given by _________________
Answer: dp/dl = -k(v2/2h)
17.Wind tunnel ______________is caused by the fact that the boundary layer grows on the walls of the working section.
Answer: Buoyancy
18.In order to correct for “horizontal buoyancy” Glauert gave a formula in which the stream wise pressure gradient is proportional to _______________
Answer: Dynamic pressure.
19.The rectangular passage between two corner vanes in a low speed tunnel should have an aspect ratio ______________
Answer: >= 6
20.The _______________effect can also be corrected using an increment in the effective airspeed.
Answer: Wake blockage