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dynamic viscosity and the speed of sound are related to the temperature as follows:
From ideal gas equation, we have: √ √ √
*( )*( *( )* 4) Draw a neat labelled graph showing the variation of aerodynamic efficiency (
with angle of attack . ratio) 5) Draw a labelled graph showing the variation of
with aerofoil thickness (in percent
chord) for two cases of nonidentical Reynolds numbers ( varies from
to
). 6) Explain in a couple of sentences why the tips of some airplane wings are bent upward. Wingtip devices are usually intended to improve the efficiency of fixedwing aircraft.
Wingtip devices increase the lift generated at the wingtip (by smoothing the airflow
across the upper wing near the tip) and reduce the liftinduced drag (or downwash)
caused by wingtip vortices, improving lifttodrag ratio. 7) Plot the variation of drag coefficient
with Reynolds number
speed flow ( varies from
to
). 8) For an airfoil having chord length
and for a sphere in low with moment values per unit span as
; calculate the location of center of pressure. Using Equation 1.22 from the textbook / formula sheet (or refer Example 1.4): This gives: 9) In a couple of sentences, explain the Buckingham Pi Theorem.
If there is a physically meaningful equation involving a certain number, n, of physical
variables, and k is the number of fundamental dimensions; then the original expression is
equivalent to an equation involving a set of p = n − k dimensionless parameters
constructed from the original variables.
The Buckingham π theorem provides a method for computing sets of dimensionless
parameters from the given variables, even if the form of the equation is still unknown;
even though the choice of dimensionless parameters is not unique. 10) On a single, clearly la...
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This document was uploaded on 03/30/2014 for the course ME 471 at Maryland.
 Winter '14
 RajatChakravarty
 Mechanical Engineering

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