Research on ice accretion on an aerofoil and its effect of aerodynamic characteristics of iced aerofoil and blade

在确定冰的形状和性质的参数组合下，对二维翼型模型进行了低温积冰风洞试验。在此之前，风洞和水滴发射器是新设计和建造的。从试验中获得了各种各样的冰形。此外，还对冰的生长速率和捕获率进行了研究，得到了一些新的结果。利用其中的一些冰形结果，制作了用于风洞试验的二维翼型模型。测量了结冰翼型周围的压力分布。结果表明，前缘积冰对翼型周围的压力分布有显著的影响。建立了基于梁理论的涡轮机叶片弹性力学方程，并进行了数值求解。结果是，越大的冰堆积，叶片的自然频率变化越大。从与激振力频率密切相关的转子转速和随转子转速增加的叶片固有频率之间的比较可以得出，当叶片在固有频率方面设计不良时，可能发生共振。采用不可压粘性流场求解程序（Navier-Stokes程序），数值研究了翼型表面积冰对翼型气动特性的影响。计算了旋翼的气动力系数，并将其应用于旋翼带冰的性能评估。转子叶片上的积冰会对转子性能产生负面影响，因此，当涡轮机位于结冰危险区域时，应考虑结冰的影响。

The low temperature wind tunnel tests for ice accretion on a two dimensional aerofoil model were carried out under the appropriate combinations of the parameters which decide the ice shape and properties. Prior to it, the wind tunnel and the droplets emitter were newly designed and built. From the tests the wide variety of ice shapes were acquired. Moreover the growth-rate of ice and the capture ratio were investigated and the several new findings were accordingly obtained. Using some of those results regarding to the ice shape, the two dimensional aerofoil models with ice for the wind tunnel testing were made. The pressure distribution around the iced aerofoil was measured. It turned out that ice accretion at the leading edge affects significantly the pressure distribution around the aerofoil with ice which was developed in particular form and size. The elastic equations for the turbine blade based on the beam theory were developed and numerically solved. The consequence was that the larger ice accretes, the more the blade's natural freqencies change. From the comparison between the rotor revolutions which are closely related to the frequency of the exciting forces and the blade's natural frequencies which increase with the rotor revolutions, it could be resulted that the resonance might occur when the blade be poorly designed in terms of the natural frequencies. The effect of ice accretion on an aerofoil on the aerodynamic characteristics was numerically investigated using the solver for the incompresible viscous flow (Navier-Stokes code). The aerodynamic coefficients were calculated and applied for performance evaluation of the rotor with ice. Ice accretion on the rotor blades affects negatively the rotor performance Therefore the effect of icing should be taken into consideration when the turbine would be situated in icing-endangered areas.