A Preliminary Study of Open Rotor Design Using a Harmonic Balance Method
A Preliminary Study of Open Rotor Design Using a Harmonic Balance Method
复制标题
谐波平衡法开式转子设计的初步研究
DOI：
--
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Kwon
中科院分区：
文献类型：
--
作者：
J. Jang;Seongim Choi;H. Kwon;D. Im;Duck;J. Kwon
开式转子发动机是下一代航空发动机之一，因为它比传统的涡扇发动机效率高30%。然而，高水平的噪声响度一直是开放式转子在航空市场中的商业用途的主要缺点。虽然已经有一些努力，以降低其噪声水平，一个开放的转子的非定常和复杂的流场的准确预测，使其难以应用的设计方法。本文介绍了一种处理低噪声开式转子非定常问题的最新设计方法。谐波平衡法是一个数量级更有效的比传统的时间精确的CFD方法被用来分析开放的转子流。为了证明谐波平衡法的准确性，风洞实验的比例模型的开放式转子进行了气动性能与谐波平衡预测进行了比较。通过谐波平衡法的流动控制方程的稳定制定，使用代理模型的设计方法，以找到一个最佳的配置，最小化的噪声水平和总功率在恒定的推力水平。使用从FfowcsWillimas Hawkings方程导出的Farassat公式计算噪声预测。选择叶片半径、转子间距和后转子桨距角变化的设计变量。参数研究，调查的灵敏度的设计参数的推力和扭矩/功率水平，以及噪声响度进行。采用遗传算法处理多目标问题，并结合克里格响应面的代理模型。从优化结果的帕累托前沿获得了最佳配置，并且示出了从基线值降低7 dB的噪声水平和4%的功率水平。
An open rotor is one of the next generation aero-engines as it has 30% higher efficiency compared to the conventional turbofan engines. However, a high level of noise loudness has been a major drawback of the open rotor for its commercial use in aviation market. Although there have been a number of efforts to reduce its noise level, an accurate prediction of unsteady and complex flow field of the open rotor makes it difficult for the design methodologies to be applied. This paper introduces one of the state-of-the-art design methodologies to handle the unsteady problem of low-noise open rotor design. A harmonic balance method which is an order of magnitude more efficient than the conventional timeaccurate CFD method is used to analyze open rotor flows. To demonstrate the accuracy of the harmonic balance method, a wind-tunnel experiment of the scaled model of the open rotor is carried out and aerodynamic performances are compared with the harmonic balance predictions. With the steady formulation of the flow governing equations through the harmonic balance method, a design method using a surrogate model is employed to find an optimum configuration that minimizes the noise level and total power at a constant thrust level. A noise prediction is computed using the Farassat formula, derived from the FfowcsWillimas Hawkings equation. Design variables of the blade radii, rotor spacing, and the pitch angle variation of the aft rotor are chosen. A parameter study to investigate the sensitivities of the design parameters to thrust and torque/power levels as well as to the noise loudness is carried out. A genetic algorithm to handle multi-objectives is used in combination with the surrogate model of Kriging response surface. An optimum configuration is obtained from the pareto front of the optimization results and shows the reduction of noise level by 7dB and power level by 4% from the baseline values.