BVI-noise generation by wing-shaped helicopter blade
Abstract
Aerodynamic noise includes a number of noise components, among which rotational noise and vortex noise (BVI-noise) make the largest contribution to the overall noise generated. Rotation noise depends on the magnitude of the velocity of the incoming blade and prevails over other noise components at significant Mach Mach numbers. Unlike rotation noise, vortex noise is evident at low helicopter flight speeds, moderate Mach numbers. In the formation of this type of noise,an important role is played by the longitudinal geometry. Therefore, recently the shape of the helicopter blade is chosen close to existing natural forms, which are as balanced as possible. One of these may be a wing-shaped blade. In this work, the problem of generating BVI noise by the wing shaped blade of a helicopter is posed and solved. The mathematical model of the problem is constructed on the previously proposed by the author and successfully tested system of aeroacoustic equations for the general case. Estimated features in this system are pulsations of sound pressure and sound potential. The calculated data of these quantities, as well as their derivatives, were used to study near and far sound fields. In particular, the dependence of the density ripple distribution is revealed from the blade geometry, the angle of attack and the blade angle to the oncoming flow. Increasing flow velocity contributes to the emergence of transverse ripples on the surface blades that dominate the longitudinal ripples by level. An interesting feature noticed in the calculations is that there are calculations for moderate Mach numbers M=0.2,0.3 situations, at certain angles of blade placement to the stream and angles of attack where rotation noise dominates eddy noise. For values Mach numbers M>0.4 rotation noise plays a major role in blade noise generation. The noise level generated is in the range 50dB≤L≤60dB, which is lower by 5-6dB for the Blue Edge blade, as well as the rounded blade. In addition, activation of the high-frequency region in the frequency spectrum of noise was observed f≈840Hz. The results of the calculations show that the blade of the wing-shaped is low-noise in the mode of maneuvers at small flight speeds.
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References
Robert M. Kufeld, Jeffrey L. Cross, William G. Bousman. A survey of Rotor Loads Distribution in Maneuvering Flight, American Helicopter Society Aeromechanics Specialists Conference, San Francisco, CA, - 1994. - January 19-21. - P. 2.4-1-2.4-15.
Brian D. Roth. Acoustic source and data acquisition system for a helicopter rotor blade-vortex Interaction (BVI) noise reduction experiment, Thesis, December, Monterey, California, - 1996. - P. 74.
P. Rauch, M. Geravais, P. Cranda, A. Baud, J., F. Hirsch, A. Walter, P. Beaumier. The Design, Development and Testing of a New Blade Concept, American Helicopter Society 67th Annual Forum, Virginia Beach, VA, - 2011. - May 3-5 - 14P.
Y. Delrieux. From design to flight testing: overview of rotocraft acoustic research at Onera for industrial application, Aerospace Lab.Journal, - 2014. - 7. - P. 1-10. https://doi.org/10.12762/2014.AL07-02
P. V. Lukianov. BVI-noise simulation of two-blade helicopter's rotor sin shape, Visnyk of V.~N.~Karazin Kharkiv National University, Ser. Mathematics, Applied Mathematics and Mechanics, - 2019. - 89. - P. 59-75. https://doi.org/10.26565/2221-5646-2019-89-05
B. S. Mattos. Overview of Rotorcraft Technology and Market. 2011, 109 p.
P. V. Lukianov. Influence of the helicopter's rotor blade tip bound vortex on BVI-noise generation, Bulletin of Chercassy University, Ser.: applied mathematics, informatics, - 2014. - 311, 18. - P. 46-58.
P. V. Lukianov. Sound generation by Taylor and Scully Vortexes and the the Blade of the Varing Cross Section, "Naukovy Visty" - Research Bulletin of National Technical University of Ukraine "Kyiv Polytechnical Institute", - 2014. - 96, 4. - P. 139-145. https://doi.org/10.20535/1810-0546.2014.4.28305
P. V. Lukianov. On one model for aeroacousics of viscous compressible gas. Part I. Analysis of existing models, dedusing of resolving system of equations, Acoustic bulletin, - 2013-2014. - 16, 2. - P. 18-30.
P. V. Lukianov. On one model for aeroacousics of viscous compressible gas. Part I. Analysis of existing models, dedusing of resolving system of equations, Acoustic bulletin, - 2013-2014. - 16, 3. - P. 31-40.
P. V. Lukianov. On one numerically-analytical approach to solving of a problem on sound generation by a thin wing. Part I. General schematic of application to planer stationary problem, Acoustic bulletin, - 2011 - 14, 3. - P. 46-52.
P. V. Lukianov. On one numerically-analytical approach to solving of a problem on sound generation by a thin wing. Part II. A schematic of application to non-stationary problems, Acoustic bulletin, - 2012 - 15, 3. - P. 45-52.
P. V. Lukianov. Influence of blade tip rounding on level of BVI-noise, Acoustic bulletin, - 2015 - 17, 2. - P. 23-37.
L. Gutin. On sound field of rotating propeller, Journal of Technical Physics, - 1936. - 5(6). - P. 899-906.
P. V. Lukianov. Sound generation by blade and vortex near interaction at oblique angle of flow streamlining, Bulletin of Kyiv National University named after T. G. Shevchenko, Ser.: phys.- math. Sciences, - 2014. - 4. - P. 81-86.
M. E. Goldstein. Aeroacoustics. 1981. McGrawHill Int. Company, New York, 296 p.
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