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MIET2510 Mechanical Design

Mechanical Design Project

Type: Individual
Total Mark: 30% of the total marks available

Design Task

Your company is working on an industrial engineering project to design a vertical axis type hydrogenerator for generating power. Hydrogenerators are used to convert the gravitational potential energy of water held in an upper reservoir into mechanical work and then into electricity through a generator. The fundamental components of a vertical axis hydro-generator are presented in the figure below [1].

A schematic diagram of the system is shown in the figure below [2].

The top end of the shaft is supported by a guide bearing to maintain horizontal position. The shaft then passes through the rotor assembly of the electric machine, torque transfer to the rotor from the shaft is through a keyed joint. Further down the shaft a thrust bearing is used to support the weight of the rotating components. The shaft then passes through the lower guide bearing after which it is connected to the turbine using a horizontal bolted connection. Through the bolted connection the weight of the turbine is supported and torque is transmitted from the turbine to the main drive shaft. The speed of rotation of the shaft can be varied using the guide vanes but is nominally 115 rpm.

As a mechatronic engineer working in this project, you are required to provide a conceptual design for the main drive shaft, bearings, keyed joint and the shaft to turbine connections.

A motion system and stress analysis can also conducted for the designed system but this is optional.

Design Considerations

The design specifications are as shown below.

  • Weight and size: Optimised to be as low as possible
    • Rotor assembly estimated 500 - 800kg
    • Turbine estimated 500 - 800kg
  • Material: Your decision
  • Shaft arrangement:
    • Single shaft passing from upper guide bearing, through rotor, thrust bearing and lower guide bearing
    • Keyed connection to rotor to allow transfer of torque from turbine shaft to rotor for generation of electricity
    • Load transfer to thrust bearing
    • Bolted connection to turbine
  • Bearings
    • Upper guide bearing
    • Lower guide bearing
    • Thrust bearing
  • Known Dimensions
    • Turbine 0.7 - 0.9 metres high
    • Rotor assembly 0.6 - 0.85 metres high
    • The total length of the rotating component assembly should not exceed 5 metres
  • Operating conditions:
    • The main drive shaft rotates at a nominal speed of 115 rpm
    • The hydrogenerator is capable of producing up to 200kW power
    • The weight of the rotating components (rotor, shaft and turbine) is 600 - 1050 kg
    • Axial and radial shock loading may need to be considered
    • Main drive shaft torque needs to be estimated
  • Life: The system is designed to operate for 8 years continuously
  • Reliability: 98% for all parts
  • Safety factor: 2 for all parts
  • Other factors and coefficients should be decided by you

Design Checklist

The following fundamental design parameters should be considered in your design:

  • Bearings
    • Select possible bearings from any manufacturer
  • Shaft:
    • Dimensions and material
    • Keyway for transfer of torque from shaft to rotor
    • Load transfer to thrust bearing
  • Connections
    • Keyed connection for transfer of torque from shaft to rotor
    • Bolted connection from shaft to turbine

Deliverables

The client is requesting the following document to be submitted.

  • A main document summarising the design process and results including details of calculations and a list of any assumptions made.
  • Details of any further information required to improve your design and move it from concept to engineering stage.
  • 2D CAD drawing of your designed system.
  • Optional: A video showing the motion analysis expected from SOLIDWORKS Simulation package.

Important Notes

  • The submission should include a main report document saved in pdf format with supporting documents (SOLIDWORKS CAD files, simulation video, MATLAB files, etc). Please upload all supporting files into a shared folder (the link to folder must be shared with the lecturer after submission and only submit the main report document on CANVAS).
  • The maximum length for the report is 15 pages excluding the title page, reference and appendices. The main documentation should be typed and submitted as a PDF.
  • The report should be formatted as follows; Times New Roman font, colour black, size 12, paragraph with line spacing of 1.5, layout with moderate margin, text distributed evenly between the margins, pages numbered on bottom right, technical data and equations should be typed properly, and all tables and figures should be labelled.
  • The report should be structured as a technical engineering report. As such it should be well formatted to help present information to the reader.
  • If there should be any parameters, variables or coefficients that are not provided in the design requirements you can can assume suitable vales to support the design process.

Reference

[1] Ibrahim Dincer, Haris Ishaq, Chapter 6 - Hydro Energy-Based Hydrogen Production, Renewable Hydrogen Production, Elsevier, 2022, Pages 191-218
[2] Sulo Lahdelma and Esko Juuso, Vibration Analysis of Cavitation in Kaplan Water Turbines, Proceedings of the 17th World Congress IFAC, Seoul, Korea, July 6-11, 2008.