【作者】 宋辰瑶；

【导师】 徐国华；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2010， 博士

【摘要】 旋翼噪声是直升机空气动力学领域具有挑战性的研究课题。基于尾迹分析,本文一方面针对悬停和前飞状态旋翼旋转噪声的计算方法和参数影响进行了研究,另一方面,针对桨-涡干扰(BVI)噪声的探测方法以及BVI噪声在近场与远场传播的方向性和辐射强度进行了深入分析,同时对新型桨尖旋翼的BVI噪声辐射特性及参数影响进行了计算。主要进行了以下几方面工作:作为前提和背景,本文首先阐述了论文的研究目的,并对直升机旋翼旋转噪声计算、BVI噪声探测及方向性与辐射特性、尾迹分析等研究的国内外现状进行了概述,指出了现有研究中存在的不足,提出了本文拟采用的研究方法。为准确计算旋翼气动载荷和噪声提供翼型气动模型,本文第二章基于Leishman-Beddoes模型,建立了一个附着流、分离流和失速流状态下的翼型非定常气动力数值计算方法,并进行了方法验证。为了用于旋转噪声的计算和桨-涡干扰的探测,本文建立了一个适于悬停和前飞状态的旋翼自由尾迹模型。应用该模型,计算了不同前进比下的旋翼自由尾迹形状、桨盘诱导入流分布以及桨叶载荷分布,验证了模型的有效性。基于Farassat 1A声学时域公式以及该自由尾迹模型,本文发展了一套适合于悬停和前飞状态下旋翼旋转噪声计算的方法。应用所建立的方法,分别进行了旋翼厚度和载荷噪声的计算,并对旋翼转速、桨叶片数、旋翼直径等不同设计参数对旋转噪声的影响进行了研究,得到了一些有实际意义的结果。然后,基于Beddoes修正尾迹模型,建立了一个新的用于旋翼前行侧和后行侧BVI噪声辐射特性和方向性分析的模型,研究了BVI噪声在前行侧和后行侧的分布特点,分析了桨叶片数、前进比、桨尖马赫数等不同参数对BVI噪声辐射特性和方向性的影响,总结出了一些BVI噪声前行侧和后行侧辐射的规律。在此基础上,本文又进一步推导和建立了一个新的用于后掠、前掠和锯齿新型桨尖旋翼BVI噪声辐射特性的分析方法,使用该方法研究了这些新型桨尖旋翼发生BVI时的特点,以及后掠、前掠和锯齿桨尖对旋翼桨-涡干扰噪声方向性的影响,得出了对降低桨-涡干扰噪声设计具有指导意义的结论。最后,基于自由尾迹分析模型,还建立了一个适合于旋翼桨-涡干扰垂直距离的平面探测方法,使用该探测方法,计算了不同状态下旋翼桨-涡干扰时的桨涡垂直距离,着重分析了桨叶片数、前进比、桨盘迎角等不同参数对桨-涡干扰垂直距离和桨-涡干扰角的影响。更多还原

【Abstract】 Rotor noise is a challenging subject in the field of helicopter aerodynamics. Based on wake analysis, on one hand, the computational method for rotor rotational noise in hover and forward flight and the effect of parameters are investigated in this thesis. On the other hand, the detective method on blade-vortex interaction and directionality of its noise in the near/far field and radiation intensity are deeply analyzed. Also, the radiation characteristics about BVI noise of modern rotors with new blade tips and parameter influences are investigated. The major contributions of the author’s research work are as follows:As the background of present work, the objectives of the research are firstly described. The research and development in the field of the helicopter rotor rotational noise, blade-vortex interaction sources detection, directionality and radiation characteristic of BVI noise, as well as wake analysis are briefly introduced. The difficulties in the current research on the BVI noise are pointed out. In addition, the methods used in the present research are briefly introduced. In order to provide an accurate airfoil aerodynamic model for computation of the rotor aerodynamic loading and noise, Chapter 2 establishes a method of computing airfoil unsteady aerodynamic forces at the attached flow, separated flow and stalled flow, based upon the Leishman-Beddoes model. The comparisons with the available experimental data are also made to show the capability of the method.Aiming at rotational noise computation and BVI detection, a free-wake model for hover and forward flight rotor is presented. By using this model, the free-wake geometry, induced inflow and loading distribution of the rotor at different advance ratios are calculated for validation purposes. By employing Farassat Acoustic Formula 1A in the time domain and combining the free-wake model, a numerical method of rotational noise computation for hover and forward flight has been developed. By the method developed, both rotor thickness and loading noise are computed. The influence of different design parameters on the rotational noise, such as rotor speed, blade number and rotor diameter, are also investigated. On the basis of the investigation, some meaningful results are obtained.Then, a new model for studying BVI noise directionality and radiation characteristics at the advancing side and retreating side of a rotor is developed with the help of the Beddoes modified wake model. The distribution features of BVI noise at the rotor advancing side and retreating side are studied, and the effect of different parameters such as blade number, advance ratio and tip Mach number, are also analyzed. Some conclusions have been drawn from analyzing the BVI noise radiation characteristics. Furthermore, a novel method of analyzing BVI noise radiation characteristics for the rotor with new blade tips such as backward-swept tip, forward-swept tip and sawtooth tip, is derived and established in this thesis. The features of the rotor BVI noise radiation with these modern blade-tips are investigated by using the method, and the influences of these modern tips on rotor BVI noise directionality and radiation characteristics are also discussed. Based on the research, some results which are helpful for the rotor design of reducing BVI noise are obtained.Finally, applying the free wake model, a plane detection method for rotor BVI miss-distance detection is developed. From this method, the miss-distance of BVI at the different conditions is computed, and the influences of the blade number, advance ratio and attack angle of tip-path-plane on the miss-distance and blade-vortex angle are emphatically analyzed.更多还原