Design and construction of mitchell tilting pad apparatus

Project Abstract

This research project focuses on the design and construction of a Mitchell tilting pad apparatus. The Mitchell tilting pad bearing is a type of fluid film bearing that is widely used in high-speed rotating machinery due to its superior performance in terms of load-carrying capacity and stability. The apparatus to be designed and constructed in this project will allow for experimental testing and analysis of the tilting pad bearing's performance under various operating conditions. The design process will involve detailed engineering calculations to determine the dimensions and specifications of the components that make up the tilting pad apparatus. This will include the tilting pad geometry, the pivot mechanism, the lubrication system, and the housing structure. Finite element analysis will be used to validate the structural integrity of the components and ensure that they can withstand the loads and stresses experienced during operation. The construction phase will involve the fabrication and assembly of the tilting pad apparatus according to the design specifications. Precision machining techniques will be employed to ensure the accuracy and quality of the components. The tilting pad bearings will be carefully installed and aligned within the apparatus to ensure proper functioning. Once the apparatus is constructed, experimental testing will be conducted to evaluate the performance of the Mitchell tilting pad bearing under different operating conditions. This will involve measuring parameters such as bearing load, pad temperatures, and vibration levels while varying the speed and load on the bearing. The data collected during testing will be analyzed to assess the bearing's performance in terms of load capacity, stability, and efficiency. The results of this research project will contribute to the understanding of the behavior of Mitchell tilting pad bearings and provide valuable insights for the design and optimization of such bearings in practical applications. The experimental data obtained from the testing will be compared with theoretical predictions and existing literature to validate the accuracy of the design and construction of the tilting pad apparatus. Overall, this project aims to advance the knowledge and technology related to Mitchell tilting pad bearings through the design, construction, and testing of an experimental apparatus. The findings of this research will have implications for the development of high-performance rotating machinery in various industrial applications.

Project Overview

<p> </p><p><em><strong>INTRODUCTION</strong></em>The Mitchell tilting pad apparatus is a hydrodynamic measuring instrument developed in the early 1880’s in the laboratory of Beauchamp Tower in England. Tower was employed to study the friction in railway journal bearings and come up with the best method of lubricating them. The Mitchell tilting pad apparatus is used broadly in two different experiments namely;1) Determination of the load carrying capacity of the slider bearing.2) Confirming the theory of the hydrodynamic lubrication.Tilting pad journal bearings are a source of both static support and dynamic stiffness and damping. Tilting pad journal bearings have a number of pads, typically four or five. Each pad in the bearing is free to rotate about a pivot and cannot support a moment. As a result, the destabilizing forces are greatly reduced or eliminated, and the bearings are no longer a potential source of rotordynamic instability. This feature has made tilting pad journal bearings the standard fluid-film bearing for most high-speed applications. High-speed rotordynamic applications often have rotors that pass through one or two bending critical speeds as the machines are accelerated to the operating speed. The damping from the fluid film bearings is required to safely pass through these bending critical speeds as the rotating element is accelerated. The damping also helps suppress potentially destabilizing forces from sources such as radial seals, balance pistons, impeller eye seals, internal friction fits, and unbalanced electromagnetic forces.</p><p><strong><em>1.1 AIMS AND OBJECTIVES OF THE PROJECT</em></strong>The project designing, constructing and testing on the Mitchell tilting pad apparatus is aimed at achieving the following objectives:1) To verify the hydrodynamic theory of lubrication as it was propounded by Beauchamp Tower in 1880 AD.2) To determine the load carrying capacity of the tilting pad slider bearing3) To provide the fluid mechanics laboratory of the Mechanical Engineering Department with a hydrodynamic fluid analyzing apparatus.4) To activate and motivate the students potentials into practically solving problems facing mankind.5) To run tests with the apparatus and compare the results obtained with the established or ideal standards.</p><p><strong><em>1.2 PROJECT JUSTIFICATION</em></strong>Engineering is known to be to be practice-oriented discipline. Inotherwords, no useful Engineering endeavor can exist in theory only, it must be applied to touch and transform life through meaningful practice. Therefore, this project task given to us is to ensure the knowledge we students gained throughout our five year degree programme and channeled towards the construction of Mechanical Engineering equipments.</p><p><strong><em>1.3 APPLICATIONS AND USES</em></strong>The Mitchell tilting pad apparatus is applicable in experiments which does not require;1) Hydrostatic lubrication2) Boundary lubrication3) Solid lubrication4) Elastohydrodynamic form of lubrication.It only finds its application useful in full film or fluid lubrications in motion, in which there is a situation that the load carrying surfaces of the bearing are separated by an adequate supply at all times of a relatively thick film of lubricant, so as to prevent metal to metal contact and that the stability thus obtained can be explained by the laws of fluid mechanics. The Mitchell tilting pad is a Mechanical Engineering apparatus with the above aims and objectives.</p><p><strong><em>1.4 LIMITATIONS</em></strong>The Mitchell tilting pad apparatus is limited to use with the specified oil viscosity (SAE20W/50) or Whitz oil which is typical automobile engine oil. The Mitchell tilting pad apparatus is also limited to operation when there is power failure or insufficient supply of power that drives the electric motor, other limitations are stipulated below;1) The use of lubricants that do not obey Newton’s law of viscous flow.2) The use of compressible lubricants3) Fluid pressure varying in the axial direction.From the limitations stated above, it is necessary to identify the Newton’s viscous effect, which states that the shear stress in the fluid is proportional to the rate of change of velocity with respect to ‘y’.</p> <br><p></p>