A CORRELATION INDICATING INCIPIENT DYNAMIC STALL

This paper proposes a correlation which attempts to relate an aerofoil 's low speed dynamic stall onset incidence to particular parameters de scribing its stall behaviour in steady conditions. These parameters, w hich can be derived from experiment or predictive algorithm, are the i ncidence of steady stall and a term related to trailing-edge separatio n characteristics. The correlation is based on a large amount of data obtained from a number of aerofoils broadly classified into two famili es: the NACA four digit series of symmetrical sections and a family of four profiles with the NACA 23012 as the generic shape. The correlati on has been extended to low pitch rates outside the ''deep'' dynamic s tall range and, whilst it pertains to stalling under ramp motions, a l ink has been established with oscillatory motions. The potential of th e correlation is demonstrated by its application to the design of a sy mmetric aerofoil for use on wind turbines.