平面叶栅尾流板开孔率对跨声速涡轮叶栅流道影响的数值分析

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

跨声速平面叶栅风洞中通常通过尾流板来改善平面叶栅周期性,针对尾流板的设计需求,利用数值模拟的方法,研究了尾流板在15%、30%、50%开孔率下对实验叶栅的影响。数值分析结果表明:叶栅尾缘激波在自由边界上反射后,返回到叶栅通道中,破坏了叶栅通道的周期性;开槽尾流板减少了反射波对叶栅通道的影响,减弱叶栅尾缘激波的反射波强度,在某特定情况下能使反射波变成膨胀波,从而提高了叶栅通道周期性;尾流板开孔率为15%时能极大地改善平面叶栅通道的周期性,相对于开孔率为50%时叶栅的周期性误差降低约16.43%。

Transonic test in linear cascade wind tunnel usually uses a tailboard to im- prove the linear cascade periodicity. In order to meet the tailboard design requirement, a tail- board 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 stem- ming from the cascade trailing edges reflected back to the passages at the boundaries distur- bing 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 un- der 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 sig- nificantly improved the periodicity of the cascade flow, reducing the periodicity error by 16.43% in related to the 50% void ratio tailboard.