The First Hybrid CRP-POD Driven Fast ROPAX Ferry (Paper)

A fast ferry equipped with the world's first hybrid CRP-POD propulsion system having the same effects as contrarotating propellers (CRP) has been developed by combining an electric pod propulsion unit and conventional diesel propulsion system.
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  Mitsubishi Heavy Industries, Ltd.Technical Review Vol. 41 No. 6 (Dec. 2004) 1 The First Hybrid CRP-PODDriven Fast ROPAX Ferryin the World A fast ferry equipped with the world's first hybrid CRP-POD propulsion system having the same effects as contra- rotating propellers (CRP) has been developed by combining an electric pod propulsion unit and conventional diesel propulsion system. With this system, energy is saved by more than 13% as compared with the conventional twin shafts and propellers system, contributing to a reduction of operation costs and of CO  2   emission. Two ferries, named HAMANASU and AKASHIA, adopting this system were delivered to Shin Nihonkai Ferry Co., Ltd. at the end of June 2004. Excellent propulsion performance of the hybrid CRP-POD system was confirmed not only by the trial Maximum speed of 32.04 knots (59.3 km/h) but also by the vessels' operational record. They have been in commercial operation between Maizuru and Otaru since July 2004, and the previous one-way cruising time of 29 hours has been shortened to 20 hours. They are two of the fastest ro-pax ferries in the world. Fig. 1 CRP POD propulsion system Table 1 Main specifications Depth (m)Wartsila12V46C x  2 unitsWartsila12V46C x  212600kW x  500min- 1 12600kW x  514min- 1 17600Daihatsu 8DK32C x  1unitDraft (m)Gross tonnage (t)Trial maximum speed (kn)Passengercapacity (persons)Vehicle capacity158 vehicles of 12 m length; 65 passenger carsMainengineMaximumoutputMaingenerator engineAuxiliarygenerator engineMaximumoutputMaximumoutputPodpropulsionunitNormaloutput(kW)Length overall (m)Breadth (m)224.827.40341811681032.048202910kW x  720min- 1 AZIPOD Type2126.0020.4InternationalJapanese NAOKI UEDA* 1 AKIRA OSHIMA* 2 TAKASHI UNSEKI* 3 SHIGETOMO FUJITA* 3 SHINGEN TAKEDA* 3 TOHRU KITAMURA* 4 *1 Shipbuilding & Ocean Development Headquarters*2 Nagasaki Research & Development Center, Technical Headquarters*3 Nagasaki Shipyard & Machinery Works*4 Shimonoseki Shipyard & Machinery Works 1. Introduction1. Introduction1. Introduction1. Introduction1. Introduction More than 20 fast ferries of the 30 knot class are op-erating in the world at present. Those fast ferriesconsume a greater amount of fuel and have very highoperation costs, while cruising economy, CO 2  emissionsand other environmental effects are also serious prob-lems in need of solution. The world's first hybrid CRP-POD driven system(FigFigFigFigFig.....11111) installed in the HAMANASU and AKASHIA is a21st century-oriented propulsion plant featuring energysaving of more than 13% of the conventional level, en-hanced cruising economy, and low environmental impact. This paper reports an outline of the new ferry, mainlywith reference to the novel propulsion system 2. Outline of the Principal Particulars2. Outline of the Principal Particulars2. Outline of the Principal Particulars2. Outline of the Principal Particulars2. Outline of the Principal Particulars  The principal particulars of the ship are shown in T T T T Table 1able 1able 1able 1able 1. To enhance the propulsion performance, the over-all length is 224.82 m, surpassing the 200 m mark forthe first time in Japan. It is the longest ferry in theworld. The main engine for propulsion and the main gen-erator engines for supplying power to the pod are twounits each of 12V46C manufactured by Wartsila, andthe pod propulsion unit is Azipod (R)  of ABB, adoptedin view of its past record and reliability.  2 Mitsubishi Heavy Industries, Ltd.Technical Review Vol. 41 No. 6 (Dec. 2004) Fig. 2 Conventional twin shafts ship (shaft bracket system)Fig. 3 CRP POD propulsion system 3. History of development3. History of development3. History of development3. History of development3. History of development  The pod propulsion unit is an azimuth type one driv-ing a propeller directly coupled with a motor byincorporating the motor in a pod unit. This propulsionunit is at the stern of the hull, and also the unit has afunction of rudder due to rotation. Thanks to its 360-degree free rotation, excellent steering performanceis realized in harbor and pier operations, together withpowerful propulsion. This compact system incorporating a propulsion mo-tor in the pod was jointly developed by Europeanelectric manufacturer and shipyard in the early 1980sfor ice breakers. The pod propulsion unit, a revolutionary system inthose days, has been employed in more than 70 ves-sels, but since it is an expensive system, it has beenused mainly in cruise passenger ships so as to makethe best of its features, including excellent steeringperformance, vibration and noise suppressing effect,and high flexibility of inboard layout.MHI initially promoted investigation into applica-tions of pod propulsion unit aiming at large cruiseships and LNG carriers. From around 2000, effortshave been concentrated on development of a novel pro-pulsion plant using the pod unit as part of campaignto reinforce the competitive power of ferries and ro-roships which belong to the main strategic category forMHI.As a result, it has been found that the CRP-PODpropulsion system, combining the conventional pro-peller propulsion system with pod propulsion, issufficiently economical and competitive in general mer-chant ships.In Europe, too, intensive studies have been madeto apply the hybrid system in ferries as an applicationof the pod propulsion unit. In April 2002, MHI started joint research with ABB, an active manufacturer whichis enthusiastically developing this concept. 4. Outline of hybrid CRP-pod-driven propulsion4. Outline of hybrid CRP-pod-driven propulsion4. Outline of hybrid CRP-pod-driven propulsion4. Outline of hybrid CRP-pod-driven propulsion4. Outline of hybrid CRP-pod-driven propulsion Generally speaking, large ferries have twin shafts andpropellers arranged symmetrically to the center line be-cause propeller diameter are limited due to limitation of draft, and because plural independent propulsion plantsare needed to assure the safety of passengers in case of trouble. For a ship adopting the twin shafts and propel-lers, the propeller shaft is generally exposed from thestreamlined hull, and is supported by bossing and brack-ets as shown in Fig. 2Fig. 2Fig. 2Fig. 2Fig. 2. This is known as the shaft bracketsystem, and the additional resistance may occupy 10 per-cent of the total resistance.As shown in Fig. 3Fig. 3Fig. 3Fig. 3Fig. 3, in this ship, the pod propulsionunit is located immediately behind the coaxial line of themain propeller of one shaft, and two propellers are ar-ranged like one set of contra-rotating propellers. The mainpropeller is a controllable pitch propeller, and is drivendirectly by two sets of medium speed diesel main enginesby way of reduction gears with clutch and intermediateshaft. The pod propeller positioned behind is an electricpropulsion unit driven by an electric motor in the pod,using electric power from the power generation plant.As a result, two sets of propellers can be installed with-out any appendages such as shaft bracket, and theresistance performance is significantly improved as com-pared with the conventional twin shafts ship. In addition,rotating the adjacent propellers in opposite directionscould realize high propulsion efficiency by reducing tan-gential water flow. (It is called contra-rotating propellers,CRP, effect.) This pod propulsion unit has a larger loss of energyconversion due to electric propulsion as compared withmechanical driving. This demerit is compensated by low-ering the distribution rate of electric propulsion. Thus,by combining the pod propulsion with conventional me-chanical drive propulsion plant, the concept of CRP isrealized, and is accordingly called as hybrid CRP-PODdriven propulsion.  Mitsubishi Heavy Industries, Ltd.Technical Review Vol. 41 No. 6 (Dec. 2004) 3 Fuel consumption: 193 tons/day 1250kW1250kW1250kW GGGGGGGG 16V46B12V46B16V46B 2760kW 12V46C12V46C12V46C12V46C 12V46B Fig. 4 Plant comparison Conventional four-engine twin shafts diesel direct drive systemHybrid CRP POD propulsion systemMain engine: 53.17MWMain generator: 3.75MWShaft generator: 2.50MWTotal: 59.42MWFuel consumption: 220 tons/dayEnergy saving effect of 13%Main engine: 25.20MWMain generator: 24.40MWAuxiliary generator: 2.76MWTotal: 52.36MW0.300.310.320.330.340.350.360.370.38 - 22% Fig. 6 Comparison of residual resistance (main hull only)    R  e  s   i   d  u  a   l  r  e  s   i  s   t  a  n  c  e  c  o  e   f   f   i  c   i  e  n   t Froude number (non-dimension speed): The subject ship: 30 kn Ro-ro ship (200m long)Service speed of 30 kn Ro-ro shipNavigation speed of the subject ship Fig. 5 Waveform calculation by CFD  Fig. 4Fig. 4Fig. 4Fig. 4Fig. 4 compares the conventional mechanical drivetwin-shafts system and the hybrid system, and showsthat the energy saving effect is as high as 13%. This plant has the same redundancy as a twin-shaftsship because the two driving systems are completely in-dependent. 5. Technical subjects in development5. Technical subjects in development5. Technical subjects in development5. Technical subjects in development5. Technical subjects in development 5.1 Propulsion performance5.1 Propulsion performance5.1 Propulsion performance5.1 Propulsion performance5.1 Propulsion performanceAt the beginning of the development, using the ex-perimental tank at MHI's Nagasaki Research &Development Center and the depressurized towing tankof MARIN in the Netherlands, which is noted for itsachievements in pod-driven ships, the resistance andpropulsion performance, and propeller fluctuation pres-sure were investigated.On the basis of the findings obtained, a hull modelfor minimizing the resistance at design speed was de-veloped by utilizing computational fluid dynamics (CFD),and this was verified at the Nagasaki R&D Center ex-perimental tank. FigFigFigFigFig.....55555 shows an example of hull sidewaveform by CFD.As a result, along with the effect of optimization of length, residual resistance decrease of 22% is realizedas compared with the 30-knot ro-ro ship developed byMHI in 1998, as shown in Fig. 6Fig. 6Fig. 6Fig. 6Fig. 6.Since the main propeller operates in the wake of thehull, it is important to incorporate a design that reducesgeneration of cavitation and propeller fluctuation pres-sure. The essential design points for the pod propellerare avoidance of tip vortex generated from the main pro-peller, and strength on the fluid force in pod steeringcondition. The pod propeller was designed jointly withABB, and perfect verification was achieved.In the design of both propellers to harmonize with eachother as the CRP, numerical calculation by CFD and modelverification were executed repeatedly. In numerical calcula-tion, the Navier-Stokes equation was solved in the propellerrunning state, the flow to the propulsion unit was calcu-lated, the propeller fluid force designed by UQCM (unsteadyquasi-continuous method), a numerical propeller calculationmethod used for years at MHI, was put back to a CFD modelby the multiblock lattice structure theory, and a theoreticalcalculation of high precision was performed.  Mitsubishi Heavy Industries, Ltd.Technical Review Vol. 41 No. 6 (Dec. 2004) 4 20.0015.0010.005.000.0-5.00-20.00-10.0010.0020.000.0020.0015.0010.005.000.0-5.00-20.00-20.00-10.0010.000.0020.0020.00-10.0010.000.00: +35-T: -35-TD T =2.95D T =3.42Ad=2.73Ad=2.98D T =2.43D T =4.03Ad=2.46Ad=3.27Ad=3.90Ad=2.3920.0015.0010.005.000.0-5.00D T =2.41 Fig. 9 Turning performance (model test) Normal seagoing (CRP mode)Pod propeller thrust onlyMain propeller thrust only (pod steering) Fig. 7 Pressure and streamline vector calculation of pod surface Rudder angle: 0 degree udder angle: degree Fig. 8 Example of cavitation observation in depressurized towing tank   Rudder angle: 0 degree 500.0400.0300.0200.0100.00.0-100.0-200.0-300.0 -100.0 0.0 100.0 300.0 500.0 700.0 900.0    X   (   M   ) Quay Fig. 10 Simulation of harbor operation (model test) Harbor steering result Y (M)Dead slow navigationSlowdownReverseand stop180-degreehead turningStern fixing Fig. 7Fig. 7Fig. 7Fig. 7Fig. 7 shows an example of calculation of pressuredistribution and speed vector on the pod surface in thepropeller running state.Fig. 8Fig. 8Fig. 8Fig. 8Fig. 8 is an example of cavitation observation using adepressurized towing tank. In the sea trial, the cavita-tion of actual ship was observed, and the results of estimation were verified.5.2 Steering performance5.2 Steering performance5.2 Steering performance5.2 Steering performance5.2 Steering performance The pod propulsion unit features high steering per-formance. In the hybrid system, steering variationscombined with the conventional propulsion system maybe considered. Fig. 9Fig. 9Fig. 9Fig. 9Fig. 9 shows three modes of turning trackchart: CRP mode, pod alone, and main propeller alone.In the main propeller alone mode, the pod propeller idlesand the pod functions as a rudder.Fig. 10Fig. 10Fig. 10Fig. 10Fig. 10 shows a track of turning-round motion by bowthruster and pod 90-degree steering from the dead slowahead in the model test. The turning motion is completedin a state close to in-situ head turning motion, and safeand prompt steering is realized in narrow waters in har-bor or at piers. The ship has an automatic control system that main-tains the output balance of pod and main propellers inthe optimum state, and during normal navigation it ispossible to operate in CRP mode to accelerate and decel-erate the pod and main propellers at the same time by asingle main engine telegraph lever. In harbor operation,by changing to the maneuvering mode, the pod and mainpropellers can be operated independently. The wing op-eration panel in the wheelhouse includes remotecontrollers for regulating the thrust of the main propel-ler, thrust and steering of the pod, and operation of thebow thruster. Although the sense of maneuvering is dif-ferent from that of existing ships, it can be learned in ashort time, and excellent maneuverability has been dem-onstrated in actual navigation.

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Jul 23, 2017


Jul 23, 2017
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