Interested in licensing information about the soft vane? Contact:
Edmane Envia
Collaboration
PATENTED TECHNOLOGY: LOW-NOISE FAN EXIT GUIDE VANES
Portions of the surface of the soft vane airfoil are porous. Chambers on the inside of the blade can reduce tone noise.
Quieter Engines
An airplane approaches--can you hear the whine of the fan? Aircraft engine fan noise is generated, in large part, when the air flow from the fan rotor hits the stationary fan exit guide vanes downstream. Reducing aircraft engine noise is dependent upon finding practical ways to lower fan noise without compromising the aerodynamic performance of the fan. One of the latest concepts for fan noise reduction is the brainchild of four NASA acousticians. The team, comprised of NASA Glenn and NASA Langley engineers, was awarded US Patent 7334998 for a low-noise exit guide vane. The concept is sometimes referred to as a &ldquo soft vane&ldquo since it tries to soften or dampen out the fluctuating pressures on the surface of the vane which cause noise. How is this done? Key features of the soft vane include specially designed chambers on the inside (called Helmholtz resonators) and a porous material covering a portion of the airfoil surface. Together these features reduce the unsteady pressure fluctuations on the vane surface without compromising its aerodynamic performance. In some versions of the design, some of the chambers may be filled with bulk absorber material to further enhance the noise mitigation capacity of the vane. The concept has been successfully demonstrated in NASA tests and continues to be improved.
Developing quiet, efficient fan systems for spaceflight or for cooling electronics here on Earth is challenging. Check out our resource list for small fan aerodynamics and acoustics.
