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Unformatted text preview: EAS 4101 - Aerodynamics Spring 2011 1/7 HW 3 1/19/11, 3 rd Homework Problem 1: A jet of water that is declined at an angle is filling a moving water car. The water car is moving away from the jet at a constant velocity U and possesses a diameter D . The liquid level in the car is ( ) h t . The jet has a diameter d and a uniform velocity jet U . A frictional force F is acting on the car. Assume that the jet is always filling the car and ignore sloshing. 1. Draw an appropriate control volume, explicitly stating unit normal vectors and flux areas. 2. List your assumptions required to solve this problem. 3. What are the pressure boundary conditions on your control volume? 4. What is the time rate of change of the liquid level? 5. What is the thrust force acting on the car by the jet of water? 6. What is the frictional force acting on the car? F U D d jet U ( ) h t EAS 4101 - Aerodynamics Spring 2011 2/7 HW 3 Problem 2: Given: A vane with a turning angle , is attached to a block which is sliding on a thin oil flilm at a terminal velocity , T U , in the x-direction is shown below. Water from a constant-area nozzle, N A , flows over the vane with a known uniform velocity, N V , that is unchanged as it flows over the vane. The oil film possesses a viscosity oil and is of thickness h . The frictional forces from the film induce a net force x F that opposes the block motion. The block possesses a wetted surface area with the film of B A . Answers b) through d) should be expressed in terms of N A , 2 A , N V , x F , oil , water , h , B A , and ( note that all variables may not be needed for each answer)....
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