Small Orifice - Fluid and Heat Mechanics - Exam, Exams of Fluid Mechanics

Download Small Orifice - Fluid and Heat Mechanics - Exam and more Exams Fluid Mechanics in PDF only on Docsity! Cork Institute of Technology Bachelor of Engineering (Honours) in Mechanical Engineering- Stage 2 (NFQ Level 8) Summer 2007 Fluid Mechanics (Time: 3 Hours) Instructions Answer FIVE questions. All questions carry equal marks Examiners: Dr. G Kelly Mr. P. Clarke Prof. M. Gilchrist Q1. a) Derive an expression for the theoretical discharge through a small orifice. State all assumptions used. Describe how is this related to actual discharge, and describe the correction factors. (8 marks) b) A spherical tank with a diameter of 1 m is half filled with water. A port at the bottom of the tank is opened to drain the tank. The hole diameter is 1 cm and the velocity Ve of the water draining can be assumed to be (2gh)1/2 where h is the elevation of the water surface above the hole. Find the time required for the tank to empty. (12 marks) Figure Q1 2 Q2. a) In relation to pressure transient theory, describe the sequence of events following a sudden closure of a valve at the end of a pipe which is being used to discharge water from a reservoir. In this context define Rapid and Slow valve closure. (10 marks) b) The initial velocity of flow of water in a pipe of length of 2000m is 3ms-1. A valve at the end of the pipe is closed in one step. Calculate the minimum closure time for this valve which can classified as rapid closure. Determine the rise in pressure due to this valve closure. Neglect the elasticity of the pipe walls but take into account the compressibility of the water in the pipe for which the bulk modulus is 2.14x109 N/m2 . (10 marks) Q3. (a) Describe a venturi meter (with the aid of diagrams) and derive an expression for the determination of flowrate through an inclined meter in terms of height difference in a differential manometer connected to the meter, and the dimensions of the meter; define all terms used. (8 marks) (b) Describe how this can be used to study the flow through an orifice plate meter. (4 marks) (c) If water (20○C) is flowing through a 10-cm orifice as shown in Figure Q3, estimate the rate of flow. Assume a typical value for Cd. (8 marks) Figure Q3