HMS Albion and HMS Bulwark vessels had multiple pump and pipe work failures within the sea water fire mains. Engineers at Babcock Marine simulated real onboard operating line-ups using Flowmaster, ultimately enabling them to recommend design improvements to reduce any further component failures
“The ability to integrate Flowmaster into a front-end spreadsheet program enabled us to provide our engineers with a fully capable and adaptable simulation package, able to be rapidly and easily tuned to real-world onboard operating line-ups.”
David Millar, Senior Design Engineer
Perhaps the biggest change in modern times is that measuring in an engineering context covers a range of techniques, all to provide the engineer with an understanding of the performance of the system. In a competitive environment where the drive to reduce through-life costs often goes hand-in-hand with a requirement for increased efficiency, the consequences of not having a thorough and detailed understanding of system response before making the first cut can be severe.
Engineers at Babcock Marine demonstrated that applying modern computational techniques affords the opportunity to understand system behavior at a detailed level without the need for expensive instrumentation and tests. It can be employed upfront or, as Babcock engineersmust do in support of the UK’s Ministry of Defence (MOD), after production.
The United Kingdom Ministry of Defence (MOD) was experiencing multiple pump and pipe work failures within the sea water fire mains on both the HMS Albion and HMS Bulwark vessels. These failures were attributed to:
- Very high cost of maintenance on pump
- Frequent mechanical seal and motor bearing failures
- Inability to meet system design requirements. Various small targeted initiatives to try and improve system performance were performed; however, it was recognized by the Marine Auxiliary Systems Integrated Project Team (MXS IPT) that a more joined up systematic, system-wide approach was required to address the root cause of the problems.
Babcock Marine’s Mechanical Engineering Group (MEG) was contracted through MXS IPT HESS (Holistic Engineering Support Strategy) Pumps, to model the entire high-pressure sea water (HPSW) system on both HMS Albion and HMS Bulwark to diagnose problems and recommend solutions. The size of the ship’s system (five fire, two normal demand, and two emergency pumps connected into a ring main with numerous cooling demands and fire fighting spray systems), meant that engineers at Babcock Marine had to develop a custom user interface designed to mimic the look and behavior of the current ship’s onboard system management software. This custom interface was developed in Microsoft Excel and fully integrated with Flowmaster, enabling service engineers to run simulations and view results through a familiar software environment. The activation of pumps and valves could be simulated through the spreadsheet by clicking on symbols. The valve and pump status was automatically updated in Flowmaster when the simulations were run. Certain systems were grouped together to improve efficiency; for example, all fire fighting sprays could be turned on in a certain zone through the click of one button, enabling the operator to model different operating scenarios. The integration of Babcock Marine’s user interface enabled engineers to validate the system designs in Flowmaster quickly and easily. Aspects such as the effects of the pump degradation and defective pressure control valves could be quickly ascertained and decisions as to whether the system would perform under ideal conditions and actual “worn” conditions could be made with confidence. Pressure readings were automatically extracted from the Flowmaster model at the actual positions of the onboard remote pressure indication to add clarity to the results. These readings were superimposed onto the model diagrammatic to give direct correlation with the readings visible on the onboard control programs.
A true life level of demand needed to be established to measure the performance of the Flowmaster model. Extensive onboard testing was done using ultrasonic flow measurement and various system line-ups to record the actual flow demands on the cooling systems. Flowmaster together with Babcock Marine’s spreadsheet-based user interface was used onboard to run what-if scenarios which were then replicated in the actual live system, with the predicted results compared to the actual system performance. These tests proved invaluable in building up an understanding of system performance requirements and the reasons behind the problems being experienced. They ultimately enabled Babcock Marine engineers to recommend design improvements that would reduce any further component failures. The effect of design shortcomings found after the system has entered into service is obvious. Perhaps what is not so clear is that the same techniques that can prevent this from happening can also aid in planning upgrades, maintenance, and refit. This project clearly demonstrates how easy it is to integrate Flowmaster with third-party software and how it enables engineers to simulate real onboard operating line-ups, using Flowmaster’s technical capability through one simple user interface. Taking advantage of modern tools like computational fluid dynamics takes the age old definition of measurement and redefines it as understanding a system and its response. What doesn’t change is the importance of getting this understanding before making the first cut.
About Babcock Marine
Babcock Marine is the UK’s premier naval support contractor. The company owns and operates both Devonport and Rosyth Royal Dockyards and manages the Clyde Submarine Base at Faslane. It is the sole support partner for the Royal Navy’ssubmarine force and is a major partnerin the provision of support to the currentsurface fleet and to the future aircraft carrier program. Flowmaster® is used within Babcock Marine’s Design and Technology Mechanical Engineering Group, which offers front-end design, analysis, and through-life support solutions. Babcock Marine was contracted by the MOD to investigate and propose solutions to frequent component failures within the sea water fire mains systems onboard both theHMS Albion and HMS Bulwark vessels.