Optimized U-turn

U-turns are used to extend the length of a pipe inside a silencer in order to reduce the noise level at low frequencies. This helps to keep the silencer compact, low weight and cost-effective. These 180-degree bends may cause turbulence, however, generating additional flow noise and neutralising the intended gains.

BOSAL has developed an innovative compact flow optimized U-turn. The geometry has been optimized to minimise the turbulent flow and propagation of high frequency acoustic waves. It reduces the high frequency flow noise by up to as much as 3dB compared to a conventional U-turn. Pressure losses are reduced by 20%.
The design further enables a reduction of silencer volume by approx. 15%. This eliminates the need for expensive half shell silencers, while at the same time delivering the desired noise comfort.


  • 3dB reduction of flow noise
  • 20% backpressure reduction
  • 15% silencer volume reduction, resulting in weight reduction
  • Elimination of half shell silencer
Bosal acoustic solutions - flow optimized U-turn
Bosal acoustic solutions - flow optimized U-turn

BOSAL is constantly developing improved acoustical solutions and state-of-the-art components. 
Discover more acoustical solutions.