Marine – Engineering a Through-Deck Design for a Marine Silencer Application
The marine industry relies heavily on powerful and reliable engines such as the MAN sequentially turbocharged 16V 28/33D rated at 7,280 kW, which require efficient air inlet silencers for quiet and smooth operation. Turbochargers are widely used in marine low-speed diesel engines to improve combustion, increase engine power, reduce fuel consumption, and reduce exhaust emissions. However, in a marine application, aerodynamic noise created by turbocharging technology brings with it the potential for negative effects in the form of high cabin noise. As requirements for marine cabin noise become tighter, noise control becomes an increasingly important component of the design consideration.
Additional challenges were present, such as the need for low static pressure, the need for a steady flow condition combined with the physical size of the silencer, and the limited available space created by a complicated hull design. These challenges led the customer to contact MIRATECH, a leading acoustic engineering solutions provider in the marine industry.
The primary objective of this case study is to demonstrate how the MIRATECH Engineering and Commercial teams collaborated with the shipyard engineers and Procurement group to design a suitable through-deck solution. This solution was for air inlet silencers that would accommodate the client’s needs, while also achieving the desired acoustic performance targets for a pair of MAN16V 28/33D main propulsion engines.
The initial silencer design specified by the client was based on a competitive design. However, due to competing goals related to size, acoustic performance, backpressure as well as other commercial and operational considerations, an off-the-shelf silencer was deemed unsuitable. The MIRATECH teams worked closely with the shipyard engineering team to devise a new, custom solution. The primary challenges included:
- Size limitations: The original off-the-shelf design was too large in diameter and overall length to fit in the designated space.
- Acoustic performance: The original standard selection silencer series did not provide suitable acoustic performance. Targets set by the client were critical in the higher frequencies to provide crew comfort and optimal vessel operation.
- Hull design: The client’s hull design was complex, requiring a through-deck solution that could accommodate the silencers and achieve the desired performance.
After careful review and customer collaboration, the MIRATECH engineering team designed a through-deck solution for two silencers that would meet the client’s needs. The silencers were to be connected using a non-restrained flexible coupling specified and approved by the shipyard.
The client demanded a substantial level of assurance regarding the functionality of the design. This objective was attained by leveraging MIRATECH’s proprietary design tools, conducting rigorous analysis and modeling, and drawing upon the team’s extensive expertise in acoustics.
The engineering analysis determined that using an annular absorptive section and an insulated bullet within a specific volume would achieve the desired acoustic performance targets while minimizing restriction. However, to accommodate the hull design, the silencer would need to be built as a two-piece unit which would then be installed as a through-deck design.
Despite the potential for long-term contracts to be lengthy and cumbersome, the client was able to swiftly transition from design to procurement with the assistance of MIRATECH’s experienced commercial lead. To ensure a smooth installation and maintenance process, the shipyard team ordered the silencers well in advance. Installation was simplified as MIRATECH provided detailed instructions and maintenance documents required by the Engineer and the shipyard to ensure a trouble free fit-up.
MIRATECH’s through-deck design solution for the air inlet silencers enabled the client to achieve the desired acoustic performance targets while accommodating the vessel’s complex hull design. The two-year collaboration with Shipyard design engineers allowed the MIRATECH team to achieve a solution that met the client’s needs while adhering to the specified materials and design parameters.
This case study highlights the importance of collaboration and innovation in engineering design to solve complex challenges in the marine industry. The through-deck design solution for the air inlet silencers of the MAN 16V 28/33D main engines shows how engineering teams can work with shipyard engineers and clients to develop creative solutions that meet the client’s needs while adhering to safety and performance standards.