Numerical Investigation into the Noise Emission of Integrated Contra-Rotating Open Rotors

集成对转开式转子噪声排放的数值研究

• 批准号: 247282928
• 负责人: Professor Dr.-Ing. Ewald Krämer
• 金额: --
• 依托单位: Institut für Aerodynamik und Gasdynamik (IAG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/247282928?language=en
• 关键词: Numerical; Investigation; into; Noise; Emission

The aim of the project is the expansion of the aerodynamic and aero-acoustic numerical process chain, consisting of a CFD solver and acoustic post-processing for the investigation into the noise shielding and reflection of an integrated contra-rotating open rotor (CROR) and its detailed validation with experimental data of a CROR model test bench installed at the Institute of Aerodynamics and Gas Dynamics. Despite its high efficiency, the CROR has not become accepted in civil aviation so far. The main reason for this is the high noise emission, which is the topic of many recent research projects. In addition to the avoidance of noise development, the integration of a CROR at the empennage of the aircraft shows great potential for noise reduction. In order to reliably predict the noise reducing impact of such integration effects qualitatively and quantitatively, an accurate comprehension of the aerodynamic and aero-acoustic phenomena is necessary. The noise generating flow mechanisms of an isolated CROR are indeed rudimentary understood, however, an in-depth knowledge of the expansion of sound of an integrated CROR does not exist. Experimental data of integrated CRORs are not freely accessible for research. Hence, there are numerical investigations but no validated simulation tools. Thus, currently a CROR test bench generating experimental data of aerodynamics and acoustics of a CROR integrated into an empennage with a pylon is built up. Thereby together with the numerical process chain, experimental and numerical data for an integrated CROR can be compared for the first time. Within this project, the numerical process chain will be expanded to calculating integrated CRORs and validated by the measured data. For this purpose, the current version of the CFD-solver will be used as well as a modified one with a higher order scheme, both together with the existing Ffowcs Williams-Hawkings solver. In addition, acoustic post-processing will be expanded with a combination of boundary-element method (BEM) and ray-tracing method (RTM). BEM will be executed for the calculation of the tonal part of the shielded and reflected sound, whereas RTM will be used for the simulation of higher frequencies. Both methods complement one another by covering different frequency domains, which is the advantage of the combination of these different methods. The expansion of low frequencies can be calculated with BEM because for this method a minimal discretization of the wavelength is necessary. In contrast to this, wavelengths have to be small against geometry for RTM, therefore the high frequency domain is covered with this method. The newly developed modules will be validated with measured data and subsequently used for the simulation of a full-scale integrated CROR.

该项目的目的是扩展空气动力学和气动声学数值处理链，包括CFD求解器和声学后处理，用于研究集成对转开放式转子（CROR）的噪声屏蔽和反射，并使用安装在空气动力学和气体动力学研究所的CROR模型试验台的实验数据对其进行详细验证。尽管它的效率很高，但到目前为止，CROR还没有被民用航空所接受。其主要原因是高噪声排放，这是许多最近的研究项目的主题。除了避免噪声的发展，在飞机尾翼上集成CROR显示出很大的降噪潜力。为了定性和定量地可靠地预测这种集成效应的降噪效果，必须准确地理解空气动力学和航空声学现象。孤立的CROR的噪声产生流动机制确实是基本的理解，但是，一个深入的知识的扩展的声音的集成CROR不存在。综合CRORs的实验数据不能免费用于研究。因此，有数值研究，但没有经过验证的模拟工具。因此，目前建立了一个CROR试验台，产生的气动和声学的实验数据的CROR集成到尾翼与挂架。因此，与数值过程链一起，可以首次比较集成CROR的实验和数值数据。在该项目中，数值过程链将扩展到计算综合CROR，并通过测量数据进行验证。为此，将使用CFD求解器的当前版本以及具有更高阶方案的修改版本，两者都与现有的Ffowcs Williams-Hawkings求解器一起使用。此外，将边界元法（BEM）和射线追踪法（RTM）相结合，扩展声学后处理。BEM将用于计算屏蔽和反射声音的音调部分，而RTM将用于模拟更高的频率。这两种方法通过覆盖不同的频域而相互补充，这是这些不同方法的组合的优点。低频的展开可以用边界元法计算，因为对于这种方法，波长的最小离散化是必要的。与此相反，对于RTM，波长必须相对于几何形状较小，因此该方法覆盖高频域。新开发的模块将通过测量数据进行验证，随后用于全尺寸综合CROR的模拟。