Prediction and Validation of Whirl Flutter Data of the Maryland Tiltrotor Rig

IF 1.4 4区工程技术 Q2 ENGINEERING, AEROSPACE

Journal of the American Helicopter Society Pub Date : 2023-01-01 DOI:10.4050/jahs.69.012011

Seyhan Gul, Anubhav Datta

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引用次数: 0

Abstract

University of Maryland's Maryland Tiltrotor Rig was tested in the Naval Surface Warfare Center Carderock Division 8-×10-ft subsonic wind tunnel. Flutter frequency and damping data were collected for wing beam and chord modes up to 100 kt. Eight configurations were tested. Baseline data are gimbal-free, freewheeling mode, wing fairings on with straight and swept-tip blades. Gimbal-locked, powered mode, and wing fairings off data were also collected, all with straight and swept-tip blades. The sweep angle is 20°, starting at 80%R. Details of the mathematical model are reported. Predictions were carried out for each configuration with the University of Maryland's new aeromechanics solver UMARC-II. Wing beam damping showed good agreement with the test data. Wing chord damping was underpredicted with a maximum of 0.9% difference. The trends for this mode for the gimbal-locked, straight blades configurations (freewheeling and powered) were not captured by the analysis. Swept-tip blades did not show a definitive increase in wing beam or chord damping for the gimbal-free configuration. However, wing chord damping increased (about 0.4% at 60 kt) due to swept-tip blades for the gimbal-locked, freewheeling configuration. Locking the gimbal increased the wing chord damping by 0.5%, which was picked up by the analysis. Powered mode also increased the wing chord damping by 0.5% compared to freewheeling mode, but the analysis did not predict this behavior. Wing beam damping test data showed an increase at higher speeds due to wing aerodynamics, although not as clearly as predictions due to scatter.

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马里兰倾转旋翼机旋翼颤振数据的预测与验证

马里兰大学的马里兰倾转旋翼钻机在海军水面作战中心卡德洛克分部8次亚音速风洞中进行了测试-×10-ft。收集了高达100 kt的翼梁和弦模态颤振频率和阻尼数据。测试了8种配置。基线数据是无平衡，自由旋转模式，机翼整流罩与直和后掠尖端叶片。还收集了平衡锁定、动力模式和机翼整流罩关闭的数据，这些数据都采用直叶和后掠叶。掠角为20°，从80%R开始。文中还报道了该数学模型的细节。使用马里兰大学新的空气力学求解器UMARC-II对每种配置进行了预测。翼梁阻尼与试验数据吻合较好。翼弦阻尼被低估，最大误差为0.9%。这种模式的趋势，为平衡锁定，直叶片配置(自由旋转和动力)没有捕获的分析。后掠叶尖没有显示出翼梁或弦阻尼在无云台配置的明确增加。然而，由于采用了固定平衡的后掠叶，机翼弦阻尼增加了(60kt时约0.4%)。锁定万向节使机翼弦阻尼增加了0.5%，这在分析中得到了证实。与自由模式相比，动力模式也增加了0.5%的翼弦阻尼，但分析没有预测到这种行为。翼梁阻尼测试数据显示，由于机翼空气动力学的影响，在更高的速度下，翼梁阻尼会增加，尽管由于散射的影响，结果并不像预测的那么明显。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of the American Helicopter Society 工程技术-工程：宇航

CiteScore

4.10

自引率

33.30%

发文量

审稿时长

>12 weeks

期刊介绍： The Journal of the American Helicopter Society is a peer-reviewed technical journal published quarterly (January, April, July and October) by AHS — The Vertical Flight Society. It is the world''s only scientific journal dedicated to vertical flight technology and is available in print and online. The Journal publishes original technical papers dealing with theory and practice of vertical flight. The Journal seeks to foster the exchange of significant new ideas and information about helicopters and V/STOL aircraft. The scope of the Journal covers the full range of research, analysis, design, manufacturing, test, operations, and support. A constantly growing list of specialty areas is included within that scope. These range from the classical specialties like aerodynamic, dynamics and structures to more recent priorities such as acoustics, materials and signature reduction and to operational issues such as design criteria, safety and reliability. (Note: semi- and nontechnical articles of more general interest reporting current events or experiences should be sent to the VFS magazine