Monday, 29 August 2011

Assignment - 4


Fluid Mechanics & Hydraulic Machinery – 4th UNIT
Assignment - 4
2009
1.         (a) A jet of water 70 mm diameter and having a velocity of 30m/s, impinges at the centre of a hemispherical vane. The linear velocity of vane is 10m/s in the direction of the jet. Find the force exerted on the vane and efficiency of the jet.
(b) Explain how the jet gets distributed at two tips when a jet of water strikes an inclined stationary plate at the centre. What will be the work done?                                            [8+8]
2.         (a) A jet of water of 86 mm diameter strikes a curved vane at the centre with a velocity of 30 m/s. The curved vane is moving with a velocity of 8m/s in the direction of the jet. Find the force exerted on the plate in the direction of the jet, power and efficiency of the jet. Assume that the plate is smooth.
(b) Explain, how you find the impact of jet striking an unsymmetrical fixed curved plate at one of the tips.                                                                                                            [8+8]
3.         (a) State the momentum equation and explain how it is used to analyze the cases of jet striking at the centre of a moving curve plate.
(b) A 50 mm diameter jet having a velocity of 40 m/s, strikes a flat plate at 450 to the normal of the plate. Find the normal force exerted on the plate when plate is stationary and when the plate is moving with a velocity of 15m/s in the direction of the jet.   [8+8]
4.         (a) A flat plate hinged about its top edge is vertically downwards. It weighs 10 KN. A jet of water 50 mm in diameter and 40 m/s velocity strikes normal to the plate at its mid point. Determine the angle of deflection where it stays in equilibrium.
(b) Analyze the case of a jet striking a fixed symmetric semi circular plate at one of the tips and derive the required equations to find the impact.                                                [8+8]
5.         (a) A jet of water of diameter 20 mm strikes a 200mm X 200mm square plate of uniform thickness with a velocity of 10m/s at the centre of the plate which is suspended vertically by a hinge on is top horizontal edge. The weight of the plate is 100 N. The jet is striking the plate normally. Calculate the force to be applied at the lower edge of the plate so that plate is kept in vertical position.
(b) What is a velocity triangle? Show the velocity triangles at inlet and out let when a jet strikes a moving curved plate.                                                                           [10+6]
6.         (a) A jet of water strikes with a velocity of 50 m/s a flat fixed plate inclined at 30 degrees with the axis of the jet. The cross sectional area of the plate is 100 cm2. Find the force exerted by the jet on the plate and the ratio in which the jet gets divided after striking.
(b) Derive the equation for the impact of jet striking a curved plate at the centre when the plate is stationary.                                                                                                            [8+8]
7.         (a) A jet of liquid with specific gravity of 0.85 strikes a fixed flat plate. The diameter of the jet is 100 mm and its velocity is 45 cm/s. Find the force exerted by the jet on the plate.
(b) Find the impact of jet striking an inclined flat plate when the plate stationary. [8+8]
8.         (a) A jet of water of 75 mm diameter strikes a curved vane at its centre with a velocity of 20m/s. The curved vane is moving with a velocity of 8m/s in the direction of the jet. The jet is deflected through an angle of 150 degrees. Calculate the force exerted on the plate in the direction of the jet. Also find the work done and efficiency of the jet.
(b) What are the radial vanes? What are the velocity triangles? What are the uses of their drawing for a typical case of a jet striking a moving plate?                                      [8+8]
2010
1.         A jet of water having a velocity of 35m/s impinges on a series of vanes moving with a velocity of 20m/s. The jet makes an angle of 300 to the direction of motion of vanes when entering and leaves at an angle of 1200. Find the angle of vane tips so that water enters and leaves without shock, the work done per unit weight of water entering the vanes and the efficiency.
2.         A jet of water having a velocity of 15m/s strikes a curved vane which is moving with a velocity of 5m/s in the same direction as that of the jet at inlet. The vane is so shaped that the jet is deflected through 1350. The diameter of jet is 100mm. Assuming the vane to be smooth find force exerted by the jet on the vane in the direction of motion, power exerted on the vane and efficiency of the vane.
3.         A jet of water having a velocity of 30m/s strikes a series of radial curved vanes mounted on a wheel which is rotating at 200 r.p.m. The jet makes an angle of 200 with the tangent to the wheel at inlet and leaves the wheel with a velocity of 5m/s at an angle of 1300 to the tangent to the wheel at outlet. Water is flowing from outward in a radial direction. The outer and inner radii of the wheel are 0.5m and 0.25m respectively. Determine vane angles at inlet and outlet, work done per unit weight of water and efficiency of the wheel.
4.         A jet of water of diameter 50mm, having a velocity of 20m/s strikes a curved vane which is moving with a velocity of 10m/s in the direction of the jet. The jet leaves the vane at an angle of 600 to the direction of motion of vane at outlet. Find the force exerted by the jet on the vane in the direction of motion and work done per second by the jet.

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