An analytical model of wake deflection due to shear flow

The main motivation behind this work is to create a purely analytical engineering model for wind turbine wake upward deflection due to shear flow, by developing a closed form solution of the velocity field due to an oblique vortex ring. The effectiveness of the model is evaluated by comparing the results with those of a free-wake model. The solution of the velocity field due to an oblique vortex ring is obtained by using the result of an upright ring along with an equivalent point method. The wake model is derived using oblique ring elements with a number of suitable assumptions. Results of wake vertical deflection are compared with a free-wake solution. A linear trend between wake deflection and shear flow exponent is found with both models. The oblique ring model shows some discrepancies from the free-wake result in terms of the dependence of the deflection on the reference tip speed ratio. The oblique ring model needs further refinements and validation with experimental work and is only currently suited for the determination of general wake kinematics. It however provides immediate results for a given input and can be useful in generating databases with wake geometry information.peer-reviewe

Performance analysis of a wind turbine driven swash plate pump for large scale offshore applications

This paper deals with the performance modelling and analysis of offshore wind turbine-driven hydraulic pumps. The concept consists of an open loop hydraulic system with the rotor main shaft directly coupled to a swash plate pump to supply pressurised sea water. A mathematical model is derived to cater for the steady state behaviour of entire system. A simplified model for the pump is implemented together with different control scheme options for regulating the rotor shaft power. A new control scheme is investigated, based on the combined use of hydraulic pressure and pitch control. Using a steady-state analysis, the study shows how the adoption of alternative control schemes in a the wind turbine-hydraulic pump system may result in higher energy yields than those from a conventional system with an electrical generator and standard pitch control for power regulation. This is in particular the case with the new control scheme investigated in this study that is based on the combined use of pressure and rotor blade pitch control.peer-reviewe

An aerodynamic study on flexed blades for VAWT applications

There is renewed interest in aerodynamics research of VAWT rotors. Lift type, Darrieus designs sometimes use flexed blades to have an ’egg-beater shape’ with an optimum Troposkien geometry to minimize the structural stress on the blades. While straight bladed VAWTs have been investigated in depth through both measurements and numerical modelling, the aerodynamics of flexed blades has not been researched with the same level of detail. Two major effects may have a substantial impact on blade performance. First, flexing at the equator causes relatively strong trailing vorticity to be released. Secondly, the blade performance at each station along the blade is influenced by self-induced velocities due to bound vorticity. The latter is not present in a straight bladed configuration. The aim of this research is to investigate these effects in relation to an innovative 4kW wind turbine concept being developed in collaboration with industry known as a self-adjusting VAWT (or SATVAWT). The approach used in this study is based on experimental and numerical work. A lifting line free-wake vortex model was developed. Wind tunnel power and hot-wire velocity measurements were performed on a scaled down, 60cm high, three bladed model in a closed wind tunnel. Results show a substantial axial wake induction at the equator resulting in a lower power generation at this position. This induction increases with increasing degree of flexure. The self-induced velocities caused by blade bound vorticity at a particular station was found to be relatively small.peer-reviewe

Digital Technologies and Election Management in Zimbabwe: Pseudo-democratic Transition and Contorted Delirium?

This article examines the extent to which the adoption of biometric voter registration in election management in Zimbabwe has appeared a phantom on the horizon regarding democratisation. While the emergence of digitalised election management brought with it expectations of credible electoral processes and outcomes in a country with a history of rampant electoral malpractices in manually managed processes, the phenomenon is yet to yield positive results regarding democratisation in Zimbabwe. Despite the shift from manually managed electoral process to a digitalised approach, the quagmire of irregularities has persisted in Zimbabwean elections. This is largely attributable to the trajectory of governance in Zimbabwe which appears to militate against the exploitation of the opportunities presented by digital technologies in democratising elections in the county. This said, the conclusion drawn from this article is that the configuration of political power, particularly issues of the breach of the democratic principles of separation of power and separation of personnel, are disingenuous to technology-induced democratic transition to credible elections. Secondary research was used to obtain data for this article as data were gathered from books, journal articles, newspaper articles and institutional reports.&nbsp

ScotGrid: Providing an Effective Distributed Tier-2 in the LHC Era

ScotGrid is a distributed Tier-2 centre in the UK with sites in Durham, Edinburgh and Glasgow. ScotGrid has undergone a huge expansion in hardware in anticipation of the LHC and now provides more than 4MSI2K and 500TB to the LHC VOs. Scaling up to this level of provision has brought many challenges to the Tier-2 and we show in this paper how we have adopted new methods of organising the centres, from fabric management and monitoring to remote management of sites to management and operational procedures, to meet these challenges. We describe how we have coped with different operational models at the sites, where Glagsow and Durham sites are managed "in house" but resources at Edinburgh are managed as a central university resource. This required the adoption of a different fabric management model at Edinburgh and a special engagement with the cluster managers. Challenges arose from the different job models of local and grid submission that required special attention to resolve. We show how ScotGrid has successfully provided an infrastructure for ATLAS and LHCb Monte Carlo production. Special attention has been paid to ensuring that user analysis functions efficiently, which has required optimisation of local storage and networking to cope with the demands of user analysis. Finally, although these Tier-2 resources are pledged to the whole VO, we have established close links with our local physics user communities as being the best way to ensure that the Tier-2 functions effectively as a part of the LHC grid computing framework..Comment: Preprint for 17th International Conference on Computing in High Energy and Nuclear Physics, 7 pages, 1 figur

Automobile Magazine: Burnout Vol.01 Ed.01

Torque, the automobile club of IITH, was started by a bunch of "gearheads", with a vision, to inculcate and nurture the infatuation with automobiles, in the students of IITH. Being one of the most active technical clubs, Torque attracts quite a lot of students, from all streams of engineering