Bluff body noise control

Abstract

An aircraft noise-reduction apparatus comprise a flow-facing element ( 1 ) and a flow control device ( 2 ) positioned downstream of the flow-facing element ( 1 ). The flow control device ( 2 ) is arranged, in use, to reduce noise induced by unsteady flow downstream of the flow-facing element ( 1 ).

1 .- 16 . (canceled) 
     
     
         17 . An aircraft noise-reduction apparatus, the apparatus comprising an aircraft structural element and a splitter plate extending downstream of the structural element and arranged, in use, to reduce noise induced by unsteady flow downstream of the structural element, wherein the splitter plate has a length which is equal to or greater than the streamwise length of the structural element. 
     
     
         18 . The aircraft noise reduction apparatus of  claim 17 , wherein the splitter plate is a passive flow control device. 
     
     
         19 . The aircraft noise reduction apparatus of  claim 17 , wherein the splitter plate extends in a substantially radial direction with respect to the structural element and is substantially aligned with the free stream airflow. 
     
     
         20 . The aircraft noise reduction apparatus of  claim 17 , wherein the splitter plate comprises a rigid plate. 
     
     
         21 . The aircraft noise reduction apparatus of  claim 17 , wherein the structural element comprises a component of an aircraft landing gear. 
     
     
         22 . A Landing gear for an aircraft comprising a noise reduction apparatus according to  claim 17 . 
     
     
         23 . An aircraft noise-reduction apparatus, the apparatus comprising an aircraft structural element and a flow control device positioned downstream of the structural element and arranged, in use, to reduce noise induced by unsteady flow downstream of the structural element, wherein the flow control device comprises a pneumatic splitter plate. 
     
     
         24 . The aircraft noise reduction apparatus of  claim 23 , wherein the pneumatic splitter plate comprises an array of nozzles. 
     
     
         25 . The aircraft noise reduction apparatus of  claim 23 , wherein, the pneumatic splitter plate comprises a plurality of holes and/or slots which are substantially aligned along the centre line of the flow-facing element. 
     
     
         26 . The aircraft noise reduction apparatus of  claim 23 , wherein the pneumatic splitter plate is a passive flow control device. 
     
     
         27 . The aircraft noise reduction apparatus of  claim 23 , wherein the structural element comprises a component of an aircraft landing gear. 
     
     
         28 . A Landing gear for an aircraft comprising a noise reduction apparatus according to  claim 23 . 
     
     
         29 . An aircraft noise-reduction apparatus, the apparatus comprising a fairing, for locating upstream of a structural element such that, in use, airflow is at least partially diverted away from the structural element, and a splitter plate provided in the cavity defined between the fairing and the structural element and arranged, in use, to reduce noise induced by unsteady flow downstream of the fairing. 
     
     
         30 . The aircraft noise reduction apparatus of  claim 29 , wherein the splitter plate is arranged to reduce recirculating flow between the fairing and the structural element. 
     
     
         31 . The aircraft noise reduction apparatus of  claim 29 , wherein the splitter plate is adapted to secure the fairing to the structural member. 
     
     
         32 . The aircraft noise reduction apparatus of  claim 29 , wherein splitter plate comprises a pneumatic splitter plate. 
     
     
         33 . The Aircraft noise reduction apparatus of  claim 29 , wherein the splitter plate is a passive flow control device 
     
     
         34 . The aircraft noise reduction apparatus of  claim 29 , wherein the structural element comprises a component of an aircraft landing gear. 
     
     
         35 . A Landing gear for an aircraft comprising a noise reduction apparatus according to  claim 29 .