High Pressure Pelton Turbine Design

Abstract

Cost of energy is one of the main reasons why wind power generation hasn’t been able to compete with fossil fuels. However, in the past decade wind energy field has made quite a big leap in making this way of energy generation cheaper and more competitive. As a result, the price of onshore wind energy has already reached the price of fossil fuel power generation. The progress has been made with offshore wind turbine technology as well, however ever increasing energy demand has forced industry to push the limits even further. Attempts are being made to build wind farms further offshore where wind resource is much higher and where more space is available. This on the other side requires new technological development and finding new ways to decrease the cost of energy.
This thesis is a part of a larger project (DOT - Delft Offshore Turbine) which represents one such attempt to make the offshore wind energy much more competitive by combining wind turbine and hydraulic turbine technology. DOT company works on the development of the fluid power transmission in offshore wind turbines, using seawater as medium. The idea is that every wind turbine drives a hydraulic pump. Each turbine thus creates a flow of water under high pressure which is converted to electricity using a Pelton turbine generator. The main objective of this thesis is to identify and try to overcome challenges in design of Pelton turbines for high water pressures, variable flow rates and
seawater conditions. In order to accomplish this objective, theoretical, experimental and numerical approach was used.
Theoretical approach was used to develop a tool for initial Pelton turbine design. Small program was developed in Python programming language which enabled faster and easier turbine dimensioning for any operating conditions based on standard Pelton turbine design procedure. Next, test rig was designed and built as part of the experimental investigation. Test was divided in two phases. Phase I was meant to show the influence of the flow rate, pressure and pressure fluctuations on the development and quality of the water jet. Pressure is measured at the inlet of the injector and flow visualization of the jet was conducted with the high speed camera. Experimental set-up for Phase
II was concluded while performing experimentation has been left out for a future research project. As last step, CFD simulation of the designed model was conducted using Ansys CFX commercial solver and results were presented and discussed.
Although, all three approaches are conducted independently each of them contributed to answering the research questions and giving a better insight in problem definition. Furthermore it helped identifying the differences between the standard Pelton turbine design and the DOT concept. The research brings
us one step closer to making DOT concept a viable sustainable energy solution for the future.