DEVELOPMENT OF A NOVEL HIGH TEMPERATURE FAN HUB DESIGN

As the process temperature of a fan system increases, the amount of heat that gets transmitted to the bearings and/or motor increases. If this is not accounted for, it can lead to catastrophic failure. The main heat conduction path is through the shaft, and certain mechanisms must be considered when looking for new solutions. These include; how heat is transmitted through the shaft or increasing the thermal resistance of the shaft, and dissipating heat as it is conducted through the shaft. These aspects must always be considered in addition to the impact of the manufacturing complexity. In the present study, an existing heat dissipation arrangement is reviewed and replaced by a new hub which reduces the time taken to machine the part, and ultimately the overall cost of the product. Techniques are employed to determine in detail the manufacturability of the existing design and determining what should be done to reduce the overall cost to manufacture. Finite Element Analysis (FEA) based techniques have been adopted to simulate the stresses the model experiences under the operating loads. Computation Fluid Dynamics (CFD) based techniques have been used to numerically simulate the designs under operating conditions, and the resulting heat transfer through the shaft compared with respect to the heat dissipation properties are analysed. Currently, a special hub is utilised for high temperature applications such as within industrial ovens and furnaces in order to dissipate heat. The hub connects the impeller to the motor shaft, the impeller would be subjected to the high temperatures whilst the motor would remain below 70°C. According to Fourier’s law heat transfer will take place through the shaft. The material the shaft is manufactured from and its geometric properties both affect the shafts overall temperature. Should the temperature become too high at the point along the shaft where the motor bearings sit, permeant damage will occur and result in bearing failure. The current hub utilised is designed to reduce the heat within the shaft through the use of fins. The is current hub design is quite labour intensive to produce leading to potentially unnecessary costs. Subsequently a new hub has been created that can be easily machined, thus reducing the overall manufacturing time leading to cost savings. The results demonstrate that although the new hub is less effective at dissipating heat, it provides a substantial cost reduction compared to the existing design, while substantially reducing the impact of the design on various aspects of production.