Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 128-133). Also available in electronic format on the Internet.

Thesis (doctoral)--Technical University of Delft, 2006 / Includes bibliographical references (p. 173-191) and index.

Horizontal axis wind turbines are by far the most common and well understood forms of wind turbine. Typically a large amount of research and development has been invested in the technology of large scale wind turbines. Unfortunately, development of small machines (rotor diameter smaller than 10 metres) has not been as forthcoming. The advantages of small turbines are that they are accessible to the individual consumer and they are a very attractive project for the home builder. The disadvantage of small turbines is that due to the negative influence of economies of scale, they tend to be costly in relation to their power output and suffer from a long-term return on investment. Furthermore, trends in the wind industry have shown that smaller machines tend to be relatively simple devices that have been developed with very little research and development. As a result, small turbines can be inefficient, unreliable and expensive to maintain. In many cases rotor design is less than optimal, with very little blade refinement. This is especially critical for small rotors due to low Reynolds Number operation. Further exacerbating the problem is that the rotors are typically not well matched to the generator. In many cases the machines are not suited to the wind speed range in which they are designed to operate, reducing the financial viability due to poor performance. It is envisaged that by applying optimising techniques and automating some of the design complexities into a software design tool, more cost-effective and viable machines can be developed that will deliver improved performance and therefore become more financially viable.

One of the biggest environmental concerns of a wind turbine is the wind turbine noise (Prospathopoulos and Voutsinas, 2007). This study assesses the noise impacts of wind turbines on the environment by comparing the micro-wind turbine noise to traditional accepted surrounding sounds. The collection of the sound level data was done by using a randomised experiment. The sound level data was then fitted to a General Linear Model to determine the relationship between the sound levels generated at a given site to the time of day, wind speed, wind direction and distance from the sound source. An additional study was conducted to determine the relationship between wind speed and the sound levels of wind turbines. The distribution of frequency components of wind turbine sound was also determined.

A modern gas turbine must be designed quicker, be more reliable, produce less emissions than its predecessors and yet the engine manufacturer must still make a profit. In order to sell their engines to the airlines, the manufacturer must show that their engines meet strict safety and reliability requirements. The creation of finite element models used for predicting temperatures and displacements of the engine component's is part of this design cycle. This thesis addresses the use of computational fluid dynamics (CFD) as a tool that can help in the prediction of iiietal temperatures for use with "industrial" problems and the associated requirements of accuracy and time-scales. The definition of 'industrial" accuracy and time-scales in this thesis is the accuracy required to enhance the modelling capability of a thermal engineer in design time-scales. A method is developed for using a commercial CFD code. FLUENT, for predicting flow and heat transfer. The code has been validated against several benchmark test cases and has shown good predictive capability and mesh independence for flow and heat transfer in the cavity between a rotating and stationary disc with and without through-flow. For cavities between co-rotating discs with radial througliflow, the predictions are acceptable, but some sensitivity of the heat transfer results to mesh spacing has been identified. The code has also been validated against some "industrial" test cases where experimental data has been available. The effects of buoyancy in the centrifugal force field are discussed and are related to a buoyancy number. The next part of the thesis develops a method of solving the heat transfer problem by coupling a finite element code, SC03, with FLUENT. The ideas are developed on two simple test cases and the problems of what information is to be passed across the coupling boundary and convergence issues are discussed. The results show that passing heat transfer coefficients and local air temperatures achieves the best convergence. The coupled method is their tested against two 'industrial problems. It is concluded that the method has considerable potential for use in design although some difficulties in applying the method are identified. Although not demonstrated, the method developed is not specific to SC03 or FLUENT and ally heat traiisfer/ CFD codes could be used.

No description available.

No description available.

Improving fuel flexibility for gas turbines is one advantageous property on the market. It may lead to increased feasibility by potential customers and thereby give increased competiveness for production and retail companies of gas turbines such as Siemens Industrial Turbomachinery in Finspång. For this reason among others SIT assigned Anton Berg to perform several ignition tests at SIT’s atmospheric combustion rig (ACR) as his master thesis project. In the ACR he tested the limits for how high amounts of inert gases (N2 and CO2) that the rig, prepared with the 3rd generation DLE-burner operative in both the SGT-700 and SGT-800 engine, could ignite on (Berg, 2012). Research made by Abdel-Gay and Bradley already in 1985 summarized methane and propane combustion articles showing that a Karlovitz number (Chemical time scale/Turbulent time scale) of 1.5 could be used as a quenching limit for turbulent combustion (Abdel-Gayed & Bradley, 1985). Furthermore in 2010 Shy et al. showed that the Karlovitz number showed good correlation to ignition transition from a flamelet to distributed regime (Shy, et al., 2010). They also showed that this ignition transition affected the ignition probability significantly. Based on the results of these studies among others a CFD concept predicting ignition probability from cold flow simulations were created and tested in several applications at Cambridge University (Soworka, et al., 2014) (Neophytou, et al., 2012). With Berg’s ignition tests as reference results and a draft for a cost effective ignition prediction model this thesis where started. With the objectives of evaluating the ignition prediction against Berg’s results and at the same time analyze if there would be any better suited igniter spot 15 cold flow simulations on the ACR burner and combustor geometry were conducted. Boundary conditions according to selected tests were chosen with fuels composition ranging from pure methane/propane to fractions of 40/60 mole% CO2 and 50/75 mole% N2. By evaluating the average Karlovitz number in spherical ignition volumes around the igniter position successful ignition could be predicted if the Karlovitz number were below 1.5. The results showed promising tendencies but no straightforward prediction could be concluded from the evaluated approach. A conclusion regarding that the turbulence model probably didn’t predict mixing good enough was made which implied that no improved igniter position could be recommended. However by development of the approach by using a more accurate turbulence model as LES for example may improve the mixing and confirm the good prediction tendencies found. Possibilities for significantly improved ignition limits were also showed for 3-19% increase in equivalence ratio around the vicinity of the igniter.

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