Suppression of Tip Vortex Cavitation Noise of Propellers using PressurePoresTM Technology

Abstract

This study aims to demonstrate the merits of pressure-relieving holes at the tip region of propellers, which is introduced as "PressurePores TM " technology as a retrofit on marine propellers to mitigate tip vortex cavitation noise for a quieter propeller. Shipping noise originates from various sources on board a vessel, amongst which the propeller cavitation is considered to dominate the overall radiated noise spectrum above the inception threshold. Thus, by strategically introducing pressure-relieving holes to modify the presence of cavitation, a reduction in the overall cavitation volume can be achieved. This mitigation technique could consequently result in a reduction of the radiated noise levels while maintaining the design efficiency as much as possible or with the least compromise. The strategic implementation of the holes was mainly aimed to reduce the tip vortex cavitation as this is one of the major contributors to the underwater noise emissions of a ship. In this paper, the details and results of a complementary numerical and experimental investigation is presented to further develop this mitigation concept for underwater radiated noise (URN) and to validate its effectiveness at model scale using a research vessel propeller. An overall finding from this study indicated that a significant reduction in cavitation noise could be achieved (up to 17 dB) at design speed with a favourable strategic arrangement of the pressure pores. Such a reduction was particularly evident in the frequency regions of utmost importance for marine fauna while the propeller lost only 2% of its efficiency.

Effect of biofouling roughness on a marine propeller's performance including cavitation and underwater radiated noise (URN)

“…lift and torque) by reducing the TVC. Therefore, akin to the other noise mitigation methodologies such as PressurePores TM [86], modification of the propeller blade geometries [87], the roughness applications on the small and strategic areas of the propeller blade tips can be an effective way for mitigation of the propeller URN for retrofitting as well as new design projects.…”

Numerical Modeling of the Behavior of Bubble Clusters in Cavitation Processes

“…Today, cavitation impact methods are used in various technologies to intensify mass transfer and hydromechanical processes [26][27][28][29]. The goal of the near future is the use of cavitation to control biochemical and biophysical processes in technological environments at the molecular level.…”

Hydroacoustic and hydrodynamic investigation of bio-inspired leading-edge tubercles on marine-ducted thrusters

“…On the other hand, most other noise mitigation strategies are focused on the cavitating propeller, such as pressure pore technology and the roughness application to unload the propeller tip and reduce tip vortex cavitation [ 10 , 11 ]. This does come at the cost of hydrodynamic performance, therefore highlighting the challenge within the maritime industry, maintaining hydrodynamic performance while simultaneously reducing the URN or vice-versa.…”