réduction des bruits et rotor

[Philippe Top-Force]

Silence! on tourne en silence  :lol:

[Mat]

un peu d'explications qui vont bien  =)

Silencing main rotors and blades to protect the environment and extend service life

Eurocopter is pursuing several methods of optimizing main rotors to reduce external noise and cabin vibrations with the goal of introducing them as soon as feasible on the company’s helicopters. One way is to change the shape of the blade, using a technology called Blue Edge™. The other is to integrate “intelligent” piezoelectric actuators into the trailing edge of the blade with a technology designated Blue Pulse™. Both Blue Edge™ and Blue Pulse™ are displayed on Eurocopter’s booth at Heli-Expo.

Blue Edge™: This revolutionary main rotor blade provides a passive reduction in noise levels, using a double-swept shape that is very different from present-day blades. The aim of this program is to reduce the noise generated by so-called blade-vortex interactions (BVI), which occur when a blade impacts a vortex, created at the tip of the blade of any helicopter.

A five-blade Blue Edge™ main rotor has been flying since July 2007 on an EC155 testbed, logging 75 flight hours and demonstrating noise reductions of 3 to 4 dB, as well as very good performance of the blade. With this safe and simple means of measureable noise reduction for helicopters now validated, Eurocopter is ready to move Blue Edge™ into production applications.

Blue Pulse™: This piezo-active rotor control system has the primary objective of reducing noise levels generated by the interference of the rotor blade tip vortices from one rotor blade with the following blades. In addition, it will significantly reduce vibrations within the helicopter airframe, increasing passenger comfort and extending the service life of sensitive components,

The control system uses three flap modules located at the trailing edge of each rotor blade. The blades’ piezoelectric actuators move the rotor flaps 15 to 40 times per second in order to completely neutralize the “slap noise” typically associated with helicopters during descent. The Blue Pulse™ technology has been flying since 2005, showing a noise reduction of up to 5 dB. Eurocopter’s evaluations with Blue Pulse™ are continuing on an EC145, while the development of a miniaturized system for production applications is advanced.

http://www.eurocopter.com/site/FO/scripts/myFO_publication.php?news_id=661&lang=EN

C'est intéressant comme techno, surtout pour les piézos (Blue Pulse)... Vous croyez que ça pourrait être utilisé pour réduire les vibrations sur les hélices de navires sensibles ? (au pif, SNLE  :lol:  )

[eckers]

Ca parait super simple en plus comme techno, si c'est juste un profil de pale, rajoute à ca un système NOTAR ca serait super silencieux. Les SNLE utilisent des carénages me semble t il. Accroissant la propulsion de l'hélice en supprimant les tourbillons parasites et en lissant le flux, ca doit peut-être joué aussi sur l'acoustique. http://www.globalsecurity.org/military/systems/aircraft/images/mh-90-notar-fly.gif

[BPCs]

Silence! on tourne en silence  :lol:

http-~~-//www.youtube.com/watch?v=dBS1NRsYuF8

surtout que pour les procédures de CCA ou close combat attack , le fait d'arriver en volant a moins de six mètres rend déjà  les hélos peut detectables... Alors là...

Ceci dit je pense que cela va aussi déboucher sur des vitesses de croisière plus élevées vu la moindre fatigue tant des eqimages que des structures mécaniques

Rappelons que le Cheyenne était difficilement contrôlable aux hautes vitesses...

[Philippe Top-Force]

 

[Philippe Top-Force]