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Aberdeen Mechanical Society
(Instituted 1888)
Minutes of Joint Meeting with the I.Mech.E. and Aberdeen Maritime Branch
Date:- 16th January 2002
Venue:- Room 226, Faculty of Management, Robert Gordon University
Chair:- Mr. J Ganley, Chairman I.Mech.E. Northeast Scotland
Present:- 48 Society and Institution members and guests
Item 1: Opening
John Ganley welcomed members, guests and visitors. Ian Wattie, AMS President, accepted AMS apologies from Myra Wattie, Alec Rennie, Harry Gold, Jim Mortimer, Sandy Mess, Carl Anders and Jim Mitchell. Ian Wattie advised the meeting that Jim Mitchell had suffered a heart attack and is in ARI. He is back on his feet, but will probably need surgery. The previous AMS meeting minutes from December were taken as read and approved.
Item 2: Modern Marine Propulsion Techniques, Dr Julia King, Director, Engineering and Technology, Marine Rolls Royce
John Ganley introduced Dr King, who had lectured and researched at Cambridge and Nottingham on fatigue, fracture and structural materials for 16 years before joining industry in 1994 as Head of Materials at Rolls Royce. She was made Director of Advanced Materials in 1996 and continued as a visiting professor at Swansea and Newcastle. Dr King was elected a Fellow of the Royal College of Engineering and appointed managing director of Rolls Royce Fan Systems before her present appointment in January 2000. She was awarded a CBE in 1999.
Rolls Royce’s business is 55% civil aerospace and is developing in synergistic areas. The marine business has been developed since 1997 from the nuclear submarines, and now turns over £1bn per annum with 6,500 employees in the UK, Norway and USA. The marine propulsion business is changing for defence, speed, space, silence, manoeuvrability, emissions, and energy efficiency. Only 4% is gas turbine powered at present. The weight/power of gas turbines is 10% of large slow-speed diesels and 25% of medium-speed diesels. As the relationship between power and speed is cubic, double the speed needs 8 times the power. Marinising engines like Trent can provide up to 50MW shaft power. This uses 85% of aero parts and technology, and inherits > 99.9% reliability.
Parsons’ Turbinia suffered problems with cavitation, and this is now being dealt with by using pumps to generate thrust. Water jets can increase local pressure to reduce cavitation and hence increase shaft speed to 1500 rpm. Using CFD technology from turbines on water jets has helped their development. Fast ships (40 knots, transatlantic crossing in 3.5 days, 25% cost of air freight) is now supported by the US military to base servicemen out of hostile areas. These ships are relatively small, and can carry 1400 x 20ft containers which is the economic optimum beyond which turnaround time defeats the purpose. Five marine Trents will drive these ships. Controls are difficult in high wave conditions, to react to sucking air at intakes. Studies are in progress for fast load shedding or storage.
Electric propulsion is improving availability from multi-turbine generator sets, giving more flexibility on space with shorter or zero shaft line. A cruise ship at 100,000 tonnes needs the same 40MW as a 3,500 tonne naval vessel. High torque density motors need a lot of space conventionally. Permanent magnet rotor/stator transverse flux motors generate high torque density, and are under development for 25% weight / power over the next 6 years. High temperature super conductors are a long-term objective to increase power / torque using liquid hydrogen for cooling as well as for fuel. The US Navy is seeking 70% reduction in costs and crew size via gas turbine electric propulsion. Gas turbines need to run at full load for best fuel economy, which will never be as good as diesel. Podded propulsors, e.g. the Millennium vessel, can sit in clear water pulling the ship, and generate more power and less noise.
Gas turbine exhaust heat recovery is used to pre-heat the gas for combustion in the WR21 engine. No-one wants steam generation on ships, so traditional combined cycle is out. Gas turbines can yield big benefits in the mid-low power range with lower SOx, NOx and smoke for sensitive areas. Over the last 30 years gas turbines have shed 40% NOx, 80% CO and 100% unburnt fuel.
Longer distance plans include fuel cells for H2 and O2, with potential for 60% - 70% thermal efficiency when coupled with gas turbine pressurisation, but size / power is still huge. We need to find non-reforming mechanisms to generate H2.
Engineering tools are being developed for system modelling, cavitation modelling with CFD, propulsor optimising and hull integration. Further developments are required in hydrodynamics, power electronics, electric machines, materials, combustion, fuel cells, and we need to open boundaries between electrical and mechanical engineering.
Item 3: Vote of Thanks
Sandy Miller, Chairman, Aberdeen Maritime Branch, offered the vote of thanks. He congratulated the speaker on her knowledge and enthusiasm. He noted the encouraging growth in shipping, the crossover from aero to marine engineering, and the pace of development.
Item 4: Next Meeting
The next meeting of the Aberdeen Mechanical Society on February 21st is Rapid Prototyping and Fuse Deposit Modelling by Mr G Burnett, 6 for 6.30 at C601, RGU Schoolhill.