Question

B1 a Show that the resistance to motion of a ship through water is given by [13] CF f(R, Fr) where the three dimensionless groups (the Force Coefficient, Reynolds number and Froude number)are given by LI /Lg pu'L were F is the resistance force, u is the speed of the ship, L is the length of the ship, ρ is the density of water, is the dynamic viscosity of water and g is the acceleration due to gravity b)For a particular type of ship with a length of 25 m, it is found that the force coefficient 12) is independent of the Reynolds number. Measurements on a 1/25 scale model being towed through water at a speed of 1 ms 1 indicated a force on the model of 2.3 N What will be the force on the full scale ship moving through water at a speed of5 m/s? B2 A square plate of uniform thickness has a mass of 12.7kg, a side length of 300mm and is hung so that it can swing freely about its upper horizontal edge. A horizontal jet of water, 20mm in diameter, strikes the plate with a velocity of 15m/s. The centreline of the jet is 150mm below the upper edge of the plate so that when the plate is vertical the jet strikes the plate normally at the centre. Find a) What force must be applied to the lower edge of the plate to keep it vertical [10] [10] [5] b) What inclination to the vertical the plate will assume under the action of the jet if allowed to swing freely c) In this latter situation, what are the horizontal and vertical components of the reaction force at the hinge

Answer 1

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C- T3 La Че-F evnS 112 μ 113 aL 冫。

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