Download Reduction of Blade-Vortex Interaction (Bvi) Noise Through X-Force Control - National Aeronautics and Space Administration file in ePub
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Keywords: blade-vortex interaction noise individual blade active control for diffusing tip vortices and decreasing blade loads to reduce the bvi noise, which.
Mar 1, 2004 actively induced harmonic blade-pitch oscillations reduce bvi noise. Rotors do, thus producing more blade-vortex interaction (bvi) noise.
Reduction of vibration, reduction of blade-vortex interaction noise level) or multi-objective optimization. A major difficulty for designers is to find the best compromise solution, without degrading the performance of the optimized rotor on other disciplines, and/or other flight conditions than those chosen for the optimization point, while.
Aug 17, 2016 current research strives to better understand and reduce the effects of these blade-vortex interactions (bvi).
Reduction of blade-vortex interaction (bvi) noise through x-force control momentum theory and the longitudinal force balance equations of a single rotor helicopter are used to develop simple expressions to describe tip-path-plane tilt and uniform inflow to the rotor.
The blade-vortex interaction noise is due to the interaction between the advancing blade and the vortexes generated by the tips of the previous rotor blade.
Technology is a viable means to reduce blade–vortex interaction (bvi) noise in rotorcraft systems. A linearized unsteady aerodynamics analysis was formulated and successfully validated with computation fluid dynamics (cfd) analysis. A simple control scheme with three control points was found to be effective for active bvi noise reduction.
Elementalist seems to require both the ele pen/reduced reservation and proliferation requiring 8 points where the last 2 for inquisitor dont seem.
An important source of noise in aeroacoustics occurs when a blade moves past a line vortex. This is particularly relevant to helicopter noise when blade vortex interactions occur during maneuvers and cause a loud thumping sound.
A study is made of the far field noise generated by transonic blade-vortex interactions (bv1), typical of helicopter main rotor noise. The vtran2 small disturbance, two-dimensional, transonic flow.
Mar 2, 2010 by changing the shape of the rotor blades -- the new product is called blue edge -- eurocopter has reduced the blade-vortex interaction.
Annoyance emitted by blade–vortex interactions occurring on helicopter main showing rotor vibratory loads reduction using higher harmonic blade pitch.
Modification of blade-vortex interactions using leading edge blowing christopher weiland abstract the interaction of an unsteady wake with a solid body can induce sizable loading of the structure, which has many detrimental side effects in both the structural and acoustic senses.
An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction.
A 3d analytical approach for open rotor blade vortex interaction(bvi) tonal noise rotor blade, analytical approach, vortex interaction, tonal noise, blade vortex.
The orthogonal blade-vortex interaction has been simulated using unsteady reynolds-averaged navier-stokes equations with turbulence closure equations.
Jan 1, 1998 the uniform inflow is adjusted to represent the inflow at certain azimuthal locations where strong blade‐vortex interaction (bvi) is likely to occur.
Yu y (1996) “miss distance for rotor blade–vortex interaction noise reduction”. In: presented at the 2nd aiaa aeroacoustics conference, state college, pa, 6–8 may google scholar zhang m, cheng l, zhou y (2006) closed-loop controlled vortex–airfoil interactions.
Up to 3 db of peak-to-peak noise reductions in the primary radiation direction were shown for the serrated blade encountering a parallel interaction.
2: blade vortex interaction (bvi) schematic in moderate-to-high speed cruise, the bvi-induced vibration is reduced since vortices are washed further downstream from the rotor blades, and the vibration is caused mainly by the unsteady aerodynamic environment in which the rotor blades are operating.
Significant reduction of helicopter blade-vortex interaction (bvi) noise is currently one of the most advanced research topics in the helicopter industry. This is due to the complex flow, the close aerodynamic and structural coupling, and the interaction of the blades with the trailing edge vortices.
This is due to blade vortex interaction (bvi), a type of loading noise.
Dec 2, 2016 basically, the blade tip shapes are optimized to reduce the noise caused the bvi (blade vortex interaction) phenomenon,especially parallel.
This paper reviews active rotor control techniques currently available for rotor blade-vortex interaction noise reduction, including higher harmonic pitch control.
Feb 25, 2010 both of these technologies are able to reduce noise by minimizing the blade- vortex interaction of the main rotor on a helicopter.
The resultant blade vortex interactions (bvis) induce impulsive airloads at vari-ous positions along the length of the blade, and these loads are associated with an intrusive external noise and often an increase in the vibration of the blades and airframe.
Flight path management and control methodology to reduce helicopter blade- vortex interaction bvi noise.
A blade vortex interaction (bvi) is an unsteady phenomenon of three-dimensional nature, which occurs when a rotor blade passes within a close proximity of the shed tip vortices from a previous blade.
Analytical results of rotor blade‐ vortex interaction airloads are presented with two different wake models in the comprehensive analysis camrad ii, and these calculated results are compared with the experimental data obtained from the higher-harmonic-control aeroacoustic rotor test (hart-i) program. The hart rotor was a 40%, mach-scaled model of the hingeless bo-105 main rotor.
Blade-vortex interaction noise blade vortex interaction (bvi) occurs when a rotor blade passes within a close proximity of the shed tip vortices from a previous blade. This causes a rapid, impulsive change in the loading on the blade resulting in the generation of highly directional impulsive loading noise.
Momentum theory and the longitudinal force balance equations of a single rotor helicopter are used to develop simple expressions to describe tip‐path‐plane tilt and uniform inflow to the rotor. The uniform inflow is adjusted to represent the inflow at certain azimuthal locations where strong blade‐vortex interaction (bvi) is likely to occur.
Response using bem on landing rotor/wake interactions -- beating sound.
Blade tip sweep is perceived to be effective in reducing bvi noise by avoiding or delaying parallel blade vortex interactions. Blade tip modifications considered included swept- tapered tip, an ogee tip, parabolic tip, anhedral and berp tips. Limited bvi noise reduction was demonstrated in model rotor experiments and flight tests.
An active control device for reducing blade-vortex interactions (bvi) noise generated by a rotorcraft, such as a helicopter, comprises a trailing edge flap located near the tip of each of the rotorcraft's rotor blades.
An acoustics test wing un aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade‐vortex interaction (bvi) noise.
Reductions in excess of 6 db of the peak bvi noise radiated towards the ground were demonstrated by compounding the effect of airframe drag and pitching.
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