โ Scribed by Ozer Igra
No coin nor oath required. For personal study only.
As part of a large project aimed at finding the optimal configuration for an aerogenerator to exploit wind power, an investigation was launched to find the most compact shroud possible. The dominant contributor to the shroud length is the structure downstream of the turbine (the diffuser). This component has an ever increasing cross-section as one progresses downstream, however, fast rate of area divergence will cause flow separation and the significant reduction in output power associated with it. It is the purpose of the present paper to demonstrate ways to overcome this difficulty. This can be achieved either by proper diversion and introduction of the shroud's external flow into the diffuser's inner boundary layer or alternatively, by the usage of a ring-flap. Wind power Diffuser augmented wind turbine Ring-flap Flow bleeding (blowing) NOTATIONS A area C chord Cv turbine load factor -P1 -P2 ยฝPq~ Cp~ nondimensional shroud exit pressure Pe -Pze 1 2 Pq P~ -P2 Cp, nondimensional pressure recovery -ยฝpq~ d diameter P pressure AP pressure difference q velocity r the ratio of the power obtained from the shrouded aerogenerator to the maximum power obtained from an ideal turbine (actuator-disc) having the same blade diameter and with the same upstream velocity, but operating in the open atmosphere p air density Subscripts o= upstream conditions t turbine section, total pressure l upstream of the turbine 2 downstream of the turbine e shroud exit plane.
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