Numerical study on the effect of the linear cascade slotted tailboard void ratio on the passage of transonic gasturbine cascade

Transonic test in linear cascade wind tunnel usually uses a tailboard to improve the linear cascade periodicity. In order to meet the tailboard design requirement, a tailboard with void ratios of 15%,30%,50% was designed and optimized with a numerical method to attenuate such effects. The numerical results indicated that, shock waves stemming from the cascade trailing edges reflected back to the passages at the boundaries disturbing the interior flow and breaking periodicity of cascade passage. A substantial attenuation of such interference was obtained via use of a slotted tailboard downstream the blade trailing edge. Meanwhile, the reflected wave strength was different from the impinging one, and under certain conditions, the reflected wave can become an expansion wave, as a consequence, the pitchwise periodicity had a considerable improvement. The 15% tailboard void ratio significantly improved the periodicity of the cascade flow, reducing the periodicity error by 1643% in related to the 50% void ratio tailboard.