"Comprehensive Renewable Energy" is the only multi-volume reference work of its type at a time when renewable energy sources are seen increasingly as realistic alternatives to fossil fuels. As the majority of information published for the target audience is currently available via a wide range of journals, seeking relevant information (be that experimental, theoretical, and computational aspects of either a fundamental or applied nature) can be a time-consuming and complicated process. "Comprehensive Renewable Energy" is arranged according to the most important themes in the field (photovoltaic technology; wind energy technology; fuel cells and hydrogen technology; biomass and biofuels production; hydropower applications; solar thermal systems: components and applications; geothermal energy; ocean energy), and as such users can feel confident that they will find all the relevant information in one place, with helpful cross-referencing between and within all the subject areas, to broaden their understanding and deepen their knowledge. It is an invaluable resource for teaching as well as in research. Available online via SciVerse ScienceDirect and in print. Editor-in Chief, Professor Ali Sayigh (Director General of WREN (World Renewable Energy Network) and Congress Chairman of WREC (World Renewable Energy Congress, UK) has assembled an impressive, world-class team of Volume Editors and Contributing Authors. Each chapter has been painstakingly reviewed and checked for consistent high quality. The result is an authoritative overview which ties the literature together and provides the user with a reliable background information and citation resource. The field of renewable energy counts several journals that are directly and indirectly concerned with the field. There is no reference work that encompasses the entire field and unites the different areas of research through deep foundational reviews. "Comprehensive Renewable Energy" fills this vacuum, and can be considered the definitive work for this subject area. It will help users apply context to the diverse journal literature offering and aid them in identifying areas for further research. Research into renewable energy is spread across a number of different disciplines and subject areas. These areas do not always share a unique identifying factor or subject themselves to clear and concise definitions. This work unites the different areas of research and allows users, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding. There are more than 1000 references from books, journals and the internet within the eight volumes. It is full of color charts, illustrations and photographs of real projects and research results from around the world. The only reference work available that encompasses the entire field of renewable energy and unites the different areas of research through deep foundational reviews. Allows readers, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding.

Comprehensive Renewable Energy

Gas turbines are widely used for aircraft propulsion, land-base power generation, and other industrial applications like trains, marines, automobiles, etc. To satisfy the fast development of advanced gas turbines, the operating temperature must be increased to improve the thermal efficiency and output work of the gas turbine engine. However, the heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is continuously increased. Thus, it is very important to cool the turbine blades for a long durability and safe operation. Cooling the blade must include cooling of the key regions being exposed to the hot gas. The blade tip region is such a critical area and is indeed difficult to cool. This results from the tip clearance gap where the complex tip leakage flow occurs and thereby local high heat loads prevail. This paper presents a literature survey of blade tip leakage flow and heat transfer, as well as research of external and internal cooling technologies. The pres...

Gas Turbine Blade Tip Heat Transfer and Cooling: A Literature Survey

Accurate numerical simulation of a high solidity Wells turbine

In spite of its mammoth physical size, the humpback whale's manoeuvrability in hunting has captured the attention of biologists as well as fluid mechanists. It has now been established that the protrusions on the leading-edges of the humpback's pectoral flippers, known as tubercles, account for this species’ agility and manoeuvrability. In the present work, Prandtl's nonlinear lifting-line theory was employed to propose a hypothesis that the favourable traits observed in the performance of tubercled lifting bodies are not exclusive to this form of leading-edge configuration. Accordingly, a novel alternative to tubercles was introduced and incorporated into the design of four airfoils that underwent wind tunnel force and pressure measurement tests in the transitional flow regime. In addition, a Computation Fluid Dynamics study was performed using the Shear Stress Transport transitional model in the context of unsteady Reynolds-Averaged Navier-Stokes at several attack angles. The results from the numerical investigation are in reasonable agreement with those of the experiments, and suggest the presence of features that are also observed in flows over tubercled foils, most notably a distinct pair of streamwise vortices for each wavelength of the tubercle-like feature.

The effect of undulating leading-edge modifications on NACA 0021 airfoil characteristics

In the past twenty years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column (OWC) concept. Wells turbine is one of the most efficient OWC technologies. This article provides an updated and a comprehensive account of the state of the art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of computational fluid dynamics (CFD) for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W-T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last five years, indicates that there is a trend that considerably depends on the CFD method.

/pdf/wells-turbine-for-wave-energy-conversion-a-review-3rjmhrk92o.pdf

Wells turbine for wave energy conversion: a review

Computational analysis of performance and flow investigation on wells turbine for wave energy conversion

Influence of fillet shapes on secondary flow field in a transonic axial flow turbine stage

The present study attempts to reduce secondary flow losses by application of streamwise endwall fence. After comprehensive analysis on selection of objective function for secondary flow loss reduction, coefficient of secondary kinetic energy (CSKE) is selected as the objective function in this study. A fence whose height varies linearly from the leading edge to the trailing edge and located in the middle of the flow passage produces least CSKE and is the optimum fence. The reduction in CSKE by the optimum fence is 27% compared to the baseline case. The geometry of the fence is new and is reported for the first time. Idea of this fence comes from the fact that the size of the passage vortex (which is the prime component of secondary flow) increases as it travels downstream, hence the height of fence should vary as the objective of fence is to block the passage vortex from crossing the passage and impinging on suction surface of the blade. Optimum fence reduced overturning and underturning of flow by more than 50% compared to the baseline case. Magnitude and spanwise penetration of the passage vortex were reduced considerably compared to the baseline case.

/pdf/secondary-flow-loss-reduction-in-a-turbine-cascade-with-a-t4gfud7goj.pdf

Secondary Flow Loss Reduction in a Turbine Cascade with a Linearly Varied Height Streamwise Endwall Fence

Effect of guide vanes on the performance of a self-rectifying air turbine with constant and variable chord rotors

In the recent past, experimental studies have shown some advantages of blade lean and sweep in axial compressors. As most of the experimental results are combined with other features, it is difficult to determine the effect of individual parameters on the performance of the compressor. The present numerical studies are aimed at understanding the performance and three-dimensional flow pattern within and at the exit of swept and unswept rotors. Three rotors, namely, unswept, 20° forward swept, and 20° backward swept rotors, are analysed with a specific intention of understanding the three-dimensional flow pattern within the rotors and also the pattern of the blade boundary layer flow. The analysis was done using a fully three-dimensional viscous CFD code CFX-5. Results indicated a reduction in pressure rise with sweep. Backward sweep adversely affects the stall margin. Forward sweep changes the streamline pattern in such a way that the suction surface streamlines are deflected towards the hub and th...

Mukka Govardhan

Papers

Computational analysis of performance and flow investigation on wells turbine for wave energy conversion

Influence of fillet shapes on secondary flow field in a transonic axial flow turbine stage

Secondary Flow Loss Reduction in a Turbine Cascade with a Linearly Varied Height Streamwise Endwall Fence

Effect of guide vanes on the performance of a self-rectifying air turbine with constant and variable chord rotors

Computational study of the effect of sweep on the performance and flow field in an axial flow compressor rotor