PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS
ICAS 2000 CONGRESSPROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSISAND CHALLENGES GOING INTO THE 21ST CENTURYKevin Early*GE Aircraft EnginesCincinnati, OH 45215Keywords: Propulsion, Airframe, Integration, Aircraft, EngineAbstractPropulsion airframe integration design andanalysis has many challenges as we move intothe 21st century. Along with the conventionalchallenges of integrating a propulsion system onan aircraft, new technologies and new businessdrivers dictate innovative approaches to thedesign process be developed and applied.On the technical side, new innovations in jetnoise suppression and new aircraft conceptssuch as the Blended Wing Body (BWB) will giverise to many challenges in propulsion systemperformance, operability, and meeting systemrequirements such as thrust reverse capability.Aircraft engine and aircraft manufacturers musthave the appropriate design and analysis tools inplace which provide the ability to react quicklyto inevitable design changes, driven byconstantly changing requirements, during theproduct development cycle.On the business side, the rapid globalizationof the business dictates that the latest electronictechnology be utilized to enable speed incommunication with global customers as well asrevenue sharing partners. More than ever, costand schedules dictate the use of analyticalmethods to minimize the amount of qualificationtesting. Design and analysis software must beflexible and capable of integrating CAD/CAM*Senior Member, AIAACopyright 2000 by GE. Published by theInternational Council of the AeronauticalSciences, with permission.and CAE tools while maintaining configurationcontrol of the product.The following paper describes some of thenew technical challenges facing the industry.Innovative methods of addressing thosechallenges are described.IntroductionPropulsion airframe integration presents uniquechallenges to the development of an aircraftsystem. Many of these challenges arise from thefact that the airframe integration issues involvemajor interfaces between aircraft and enginemanufacturers. Good working relationships [1,2]between these two entities is essential for asuccessful business venture.From the engine manufacturers point ofview, each working relationship with eachaircraft manufacturer is different. In fact, evenwiththesameaircraftmanufacturer,relationships for different applications can vary.Items which vary from program to programinclude which business entity has responsibilityfor various components, such as inlets, exhaustsystems, thrust reverser, engine mount pylons,etc.This significant variation in responsibilityfrom program to program places a uniquechallenge to the installation aerodynamicsorganization of the aircraft engine manufacturer.The success of any manufacturing concern in thepresent highly competitive global market zed to ensure speed in the productdevelopment cycle, while maintaining quality6103.1
Kevin Earlyand high customer value. GE Aircraft Enginesthrough its Six Sigma and e-business initiativeshas put these standard processes in place, and iscontinuously improving each process.Two key enabling technologies are requiredto meet the challenges ahead for the installationaerodynamics technology discipline; The use ofhigh fidelity analytical tools, primarily CFD, andthe use of rapidly developing informationtechnology including tools that enable concurrentproduct development, Product Data Management(PDM), and product configuration control. CFDis well established today in the designcommunity but productive, CFD based, designsystems, which can be developed and maintainedat a reasonable cost while producing high qualityresults, are not as prevalent. When these systemsare put in place effectively, the rate at whichdesign iterations can be evaluated, can quicklymake the effort required to manage the datagenerated significant. Advanced informationtechnology is required to maintain and documentthe design, analysis and evaluation process.In this paper, we will examine the use anddevelopment of advanced analysis les. We will then describe how these toolscan be integrated, using advanced informationtechnology, to address future propulsion airframeintegration challenges, in a multidisciplinarydesign environment.CFD Based Design SystemsCFD based design systems have been usedeffectively now for several years. Essential to aproductive design system is an efficient methodof geometry definition.For commercialinstallations, GE aircraft engines has developed aICALMNX 1NacelleSXMIN 60.000SCALEPARAMETESMENUSXMAX 420.00CUTON SCREEN PICTURE OFCONFIGURATIONSYMIN -240.00SYMAX 120.00ScalMOREPTS 0ISYMBOL 0SYMSIZE .00100DELTA18 12.800DELTA8 .0IBIFURCA 1IPREV 1ISQUARE 0BISCALEX 1.000BifurcationBISCALEX 1.000BISHIFTX .0BISCALEW 1.000BISCALEW 1.000BISHIFTW .0KCOLOR cellInlet2DetailOutlinePROGRAM CONTROLSInsertDataZoomCopReturnFigure 1. Nacelle geometry generation tool user's view.6103.2
PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS AND CHALLENGESGOING INTO THE 21st CENTURYC1A Mn 0.82 ALPHAI -1.0 MFR 0.651.8.6ANALYSISTEST DATA.2.4IDEAL MACH NUMBER1.21.41.6CROWN, THETA 00nacelle geometry generation package (Figure 1)that can rapidly generate nacelle flow lines.Virtually every component of the entire threedimensional geometry can be generated using aset of standardized parameters. This includes theinlet, from the fan face through the highlight andouter flow path, the nacelle external geometryincluding consideration for the thrust reverserand nacelle internal components and accessories,the fan duct, fan nozzle, core cowl, aft centerbody and duct bifurcation’s.All of the above flow lines are generatedusing established geometric curve designpractices and take into account lessons learnedfrom previous designs. Also built into thispackage are design rules which, based on thegeometric and historical data, calculate initialweight, loss and inlet capability estimates.Once the flow lines have been generated,they are transferred as input to individualcomponent CFD analysis tools tailored to thatparticular component. An example of one thesecomponent tailored tools is illustrated in figure 2,which is used for the aerodynamic analysis ofisolated nacelles [3]. The plot shows predictedstatic pressure distributions, (plotted as idealMach number), compared with experimentaldata. Excellent agreement of this type can beobtained on a routine basis using these types oftailored tools.This tool, in conjunction with the nacellegeometry package, is used extensively to rapidlyscreen nacelle inlet design concepts and evaluatedesign changes encountered during the productdevelopment cycle. The tool can also be used torapidly evaluate operating condition changes toexisting products such as an increased thrustrating for an existing engine or using a commonnacelle on a new derivative engine.Output from this particular componentanalysis are used to evaluate, nacelleaerodynamic loads, inlet recovery and drag forengine and aircraft performance, high angle ofattack and cross-wind capability, and inlet100120140160180200220240260280300320340Figure 2. Isolated nacelle analysis CFD baseddesign system results compared with test data.distortion to aid in the evaluation of engineoperability characteristics.Exercising these design tools very early onin the preliminary design phase of an aircraftsystem program, enables a high degree ofconfidence in predicted quantities over a widerange of operating conditions. By evaluating arange of operating conditions which includespossible requirement changes during the aircraftsystem development, as well as potential growthapplications, flow paths can be set extremelyearly in product development. This allows forearly evaluation by other downstream functionsto minimize the throughput cycle.Of course CFD has not totally replaced theneed for component testing. It has significantlyreduced the time required to optimize a design inrelative terms, often to the extent that only oneconfiguration is required to be tested todetermine the absolute value of key performanceparameters.The use of the tailored design system can bevery productive but there are drawbacks.Maintenance of the system, to add new e, analysis of designs not originallycreated within the system can be difficult if notimpossible.6103.3
Kevin EarlyIntegrated Design SystemsThe tailored design system described worksextremely well for conventional configurations.New design innovations however may not lendthemselves to the established design rules in anexisting system. Advanced methods must beused which can evaluate new design conceptsefficiently. The following is a specific exampleof how these advanced methods can be used onunconventional design challenges.For many applications currently underdevelopment, innovative concepts to reduce jetnoise are under investigation. Most prominentamong these concepts is the use of chevronexhaust nozzles [4] (Figure 3).Figure 3. Chevron core exhaust nozzleThese nozzles have been demonstrated todecrease jet noise effective perceived noise levelswhile having little impact on thrust performance.Reduced noise is essentially achieved bychanging jet plume mixing rates to move thenoise generated to frequency ranges that are lessannoying to the human ear.There are two major markets for chevronexhaust nozzle technology, retrofit of currentengines in the fleet, and as an offering to newapplications. From an aircraft integration pointof view, the chevron nozzle could impact themounting aft pylon, jet plume impingementcharacteristics on flaps, landing gear doors and inextreme cases, the aircraft tail structure, and theextent of exhaust hazard zones for groundoperations.The challenge is to have tools in place torapidly evaluate these designs not only from theengine acoustic and performance perspective butalso in terms of aircraft integration. A largehistorical database exists for conventional planerexit exhaust systems. From this database, wellestablished analysis techniques have beendeveloped to quickly predict aircraft integrationimpacts. These methods are often not applicableto chevron exhaust nozzle designs and moreadvanced methods including high fidelity CFDmust be used.As with the well-established componentdesign methods, the new productive designmethods start with flexible geometry definition.Of course geometry is the basis of mostdownstream engineering functions once theaerodynamic flow path has been set. High-endCAD systems now have the capability to define3D geometry using engineering basedparameters. These parameters can be driven byengineering design rules. The electronic modelcan be viewed differently depending on theengineering function, e.g. aerodynamic ormechanical design. Electronic CAD models thatutilize these advanced features are referred to asmaster models.Figure 4 shows the aerodynamicrepresentation of a parametric master model usedto generate chevron nozzle geometry. The threeFigure 4. Aerodynamic representation ofchevron paramtric master model.6103.4
PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS AND CHALLENGESGOING INTO THE 21st CENTURYFigure 5. CFD computational grids, of chevron nozzle periodic sectors, generated using automated replayable method driven by CAD parametric master model.dimensional representation of the nozzle canquickly be generated using knowledge based [5]parameters.These parameters can describegeometric features and functions that are basedon rules which capture the methodology used foraerodynamic design and analysis, mechanicalstress, and manufacturing process development.This master model can then be used bymultiple downstreamfunctionsensuringinterdisciplinary commonality.From theinstallation aerodynamics point of view, thisfunction is primarily CFD for aerodynamicperformance evaluation, and preliminaryscreening of acoustic performance. Essential tothe CFD analysis process is the generation of ahigh quality computational grid. Considerationmust be given to the type of grid to be useddepending on the intent of the prediction. Forthis particular application a blocked structuredgrid (Figure 5) is used for a higher degree ofconfidence in the turbulent mixing predictioncapabilities.Accurate geometric representation isimportant to ensure quality results. Fortunately,developers of commercially available software,applicable to different parts of the design cycle,are cognizant of the need for common geometricrepresentation. Some suppliers of this type ofsoftware have even collaborated to developessentially direct interfaces between theirproducts through Application ProgrammingInterfaces (APIs). This capability allows directtransfer of CAD generated geometry into the Depending on the level of integrationbetween the products, functional parametervalues used in the downstream function canactually be assigned in the CAD system. For aCFD application this includes grid density andspacingparameters,surfaceboundaryspecification etc. This offers a tremendousadvantage in productivity during the designiteration process. If the design change is suchthat the grid block structure topology does notchange, a new computational grid can begenerated in a matter of minutes.Figure 6. CFD prediction of conventional planerexit and chevron exhaust nozzles6103.5
Kevin EarlyThe two grids shown in figure 5 weregenerated using this technique. This type ofmodel and system can be used effectively toconduct Design of Experiments (DOEs)analytical studies. This allows for a rapidunderstanding of the design space in terms ofperformance and acoustic trades for a particularapplication. Figure 6 shows CFD predictedtemperature contours and plume mixingcharacteristics from such a study.Installed AnalysisThe installed engine flow field analysis forpropulsion airframe integration analysis isinherently more challenging than the isolatedcomponent analysis. The use of block structuredgrid techniques to solve this problem can be verytime consuming to the point that CFD analysiscan not readily impact the design cycle.Chimera grid techniques have been used in thisapplication with only moderate improvement indesign iteration time.Unstructured grid generation tools, , and their accompanying solvers,have been developed to the point that oncegeometry is provided in the required format, theycan be used productively in a designenvironment. In the past, the specification of thisgeometry was ad hoc and could not respondquickly to the significant geometric changes.The key to productive use of any of thesetechniques is the use of standardized underlyinggeometry, e.g. a parasolid. This geometryrepresentation is used by many of thecommercially available CAD, CAE, and CFDsoftware suppliers.For installed predictions, the isolatedcomponents of the fuselage, wing, and nacelleare assembled within the CAD system. Theindividual components, and their relativepositions, can be defined parametrically. Theparametric representation allows for rapidchanges. Once the configuration is set, aparasolid of the fluid is created. This parasolid isthen imported into the grid generation package.If viscous effects are important to theprediction, some packages now have the abilityto inflate a prismatic grid from the solid surface.This technique offers greater accuracy and moreeconomical use of grid than the use of tetrahedralcells in the boundary layer. Figure 7 shows aprismatic layer, inflated from the surface,beneath the tetrahedron cell volume.PrismaticInflationLayerFigure 7. Inflated prismatic grid beneathtetrahedron volume grid for accurate predictionof viscous effects on a nacelle inlet.In addition to providing grid that canaccurately predict viscous effects, theunstructured grid must conform and add griddensity to geometric regions with discontinuitiesand high curvature. Some of these solvers haveadaptive capabilities to cluster the grid not onlyto resolve geometric features, but flow fieldfeatures as illustrated in figure 8. The ability toadapt the unstructured grid to local flow fieldInitial GridRefined GridMach NumberContoursFigure 8. Automatic local grid refinement used toaccurately resolve flow field features.6103.6
PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS AND CHALLENGESGOING INTO THE 21st CENTURYgradients is important in that the unstructuredgrid solvers inherently use more computerresources for a given number of computationalcells.In order to take advantage of theproductivity increases, which automatic gridgeneration of unstructured codes offer, automaticgrid flow field adaptation is essential.For the installed propulsion system problemtoday, these unstructured grid techniques areused extensively to evaluate qualitative flowfield effects. Qualitative insight into the complexinstalled flow field can have dramatic impact onthe installation.Often quantitative deltasbetween two designs can be determined. Figure9 shows a typical result for a fuselage enginemounted application. As computer capabilityand software robustness improves, andappropriate validation of these methods isperformed, detailed quantitative predictions willbecome possible.Bombardier CRJ. New entries by FairchildDornier and Embraer are also being offered.These applications represent the first time thatrelatively high bypass turbofans are being used inthis thrust class and size of aircraft. In the lattertwo applications, wing mounted installations arebeing employed.On the other end of the spectrum, thedevelopment of the Airbus A3XX and theBoeing 777-200/300 will offer unprecedentedentries in the long-range market.Thediverseness of the marketplace, the establishmentof the true global economy, and the complexbusiness relationships of these new businessventures, present significant challenges todevelop high quality designs in a competitive,productive environment. High quality designtools and standardized processes to apply thesetools are required to meet these challenges.In the future, the challenge of analyzingadvanced designs will dictate the use ofadvanced techniques for quantitative analysis.Several unconventional concepts are beingexamined to achieve greater capacity andimproved performance [6]. Concepts like theBWB configuration (Figure 10) where engineinlets and airframe are closely coupled, willmake it very difficult to analyze componentsisolated from one another.Figure 9. Unstructured flow field analysis offuselage mounted installation.Design ChallengesThe commercial airline industry is growingrapidly in terms of the current fleet's passengerand freight usage, as well as in new productdevelopment.Stricter noise and emissionsregulations are requiring engine modifications orreplacements. At the same time new aircraft arebeing developed requiring new engineapplications.The turbofan engine has established astronghold in the regional market through theFigure 10. Blended Wing Body concept, withhighly integrated, “buried”, engine inlets [6].Published with PermissionThe highly integrated inlet and airframeof such concepts could have significant impacton the propulsion system characteristics6103.7
Kevin Earlyincluding engine operability and thrust reverseoperation.In order to reduce the drag of pylons whichclassically offset the engine nacelle from theaircraft surface flow path, concepts like the BWBwill allow the boundary layer developed forwardof the engine face to be ingested by the inlet.This could impact not only engine performance,but the total pressure distortion seen by theengine fan, could be detrimental to its operatingcharacteristics.Innovative flow control mechanisms likemicro-blowing and synthetic jets willundoubtedly need to be developed to minimize oreliminate these potential adverse effects. Thesedevices have been shown in laboratory typeenvironments to control boundary layer thicknessand reduce the tendency for separation.The flow field phenomena produced bythese devices are of a scale and complexity suchthat they are not typically considered in thepresent mainstream, design and analysisenvironment. They typically involve geometricfeatures that are of much smaller scale than thecharacteristic dimensions typical of propulsionairframe integration predictions. They also oftenutilize unsteady flow phenomena at very highfrequencies. Again, characteristics not routinelyconsidered.Techniques must be developed to simulatethese devices in a design environment. It ispossible that the flow characteristics theyproduce could be simulated through the use ofinnovative surface boundary conditions in CFDor other conventional methods. If not, othermore innovative techniques will need to bedeveloped, up to and including direct simulation.As computer capabilities increase, this may bepossible but this capability will not be availablein the near future at least in a production designenvironment.Engine thrust reverse capability, if requiredon highly integrated concepts, needs to becarefully examined. Over the decades, largecommercial aircraft have come to rely on enginereverse thrust for braking on landing. Indeed, ininclement weather, reverse thrust can be essentialfor safe operation.Significant practical experience has beendeveloped to design and evaluate thrust reversecapability on conventional aircraft. There areseveral significant factors which must beconsidered in thrust reverse operation. From theengine stand point, turbo-machinery operabilityis of key concern. This involves the ability tocreate reverse flow splay patterns from theengine fan stream which provide minimalpressure distortion impact on the fan.Hot gas re-ingestion must also beconsidered for engine operability. This involvesensuring that while in reverse thrust operation,interactions between the reverse flow stream,aircraft flow field, and ground planeimpingement, doesn’t cause hot gases to be reingested into the engine inlet.From the aircraft point of view, reversestream fuselage impingement and aircraft controlmust be considered. This includes aircraftattitude stability and control as well ensuring thatthe reverse thrust flow field does not negateaircraft drag also needed for braking purposes.Of course the engine and aircraftconsiderations are highly integrated. Designswith high degrees of propulsion airframeintegration, will require significant developmentof both analytical and experimental methods, foraccurate predictions.Multidisciplinary Design IntegrationIn order to develop advanced designs in thefuture, in the product development cycle timethat the industry demands, multidisciplinarydesign integration systems must be utilized.These systems must integrate not only the subfunctional disciplines of aerodynamic design andanalysis as described in this paper but othermajor functional disciplines. These includeproduct definition, mechanical stress and 03.8
PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS AND CHALLENGESGOING INTO THE 21st CENTURYKnowledge BasedDesign ParametersIsolated ComponentAnalysisStress AnalysisCAEC1A Mn 0.82 ALPHAI -1.0 MFR 0.651.8.6ANALYSISTEST DATA0.2.4IDEAL MACH NUMBER1.21.41.6CROWN, THETA 0100120140160180200220240260280300320340RSP’s andCustomersAdvanced ComponentAnalysisInstalled AnalysisParametricMaster ModelEntire ProductDevelopment Life CycleManaged Electronically byPDMDPA/DPUFigure 11. Schematic description of a linked model, multidisciplinary design environmentEach of these functions have developedproductive design systems which are essentiallystand alone in the sense that geometry is oftengenerated, analyzed, changed, and nment.Once the design has beendeveloped to a point that the specific discipline’srequirements are met, the results are passed on toother functions performing design and analysisof their own. Often the results indicate that thedesigns are in conflict and major, oftenexpensive, design changes must be made.As stated in the introduction, this interactionprocess can be more difficult for propulsionairframe integration development since, inaddition to multiple disciplines, multiplecompanies are ased,concurrentproductdevelopment systems. Advanced informationtechnology has made it possible to develop6103.9
Kevin Earlyproduct data management systems in whichengineeringanalysissoftwarecanbeencapsulated within the PDM.Many of these systems are being developedby CAD software providers and indeed are oftenfully integrated with the CAD system. This isfortunate since many engineering functions,including propulsion system development, areutilizing CAD based development tools. Thesesystems are based on relational databases. IfRevenue Sharing Partners (RSPs) and customersare also using a similar based product, data maybe transferred electronically and remain underconfiguration control.The PDM provides a means of providingrevision control to the multitudes of designiterations, which are made possible by everincreasing computer speed and informationtechnology. This is important not just from aparticular discipline’s point of view, but toensure all functions are using the proper revisionof other disciplines in which their effort isdependent.The other major advantage of the PDM isthat it enables the use of the exact same data.Storing all data in a central locationaccomplishes this. All disciplines using that dataaccess it from the central location, not from acopy stored at their local workstation. This incombination with revision control ensures that alldisciplines have access to the latest revision ofall data immediately upon its release. Analysismodels are electronically linked to this geometryand can be updated automatically to reflect thelatest revision. A schematic of this linked modelenvironment is shown in figure 11. Most PDMsare being developed using web technology. Thisallows for rapid notification of effecteddisciplines when a new design revision has beenreleased.In the schematic shown, all of the functionsdescribed earlier, plus other discipline functions,are driven from a common master model,developed from knowledge based parameters.All of the functions are encapsulated with in thePDM, as symbolized by the large blue rectangle.This ensures all functions are using the samegeometry, and revision control is maintained.One of the functions shown is the DigitalPre Assembly / Digital Mock Up (DPA/DMU).The DPA/DMU is now an integral part of theinterfaces between a particular manufacturer andtheir RSP’s and customers. Through the use oftranslators, common geometry can be maintainedwith these entities as well. If these entities arealso using PDM technology, revision control canbe maintained across companies.ConclusionsThis paper has discussed just some of thechallenges being faced in the area of propulsionairframe integration today. These challenges willonly become greater as highly integrated designsevolve, and global business relationshipscontinue to increase.Some of the tools required to meet thesechallenges have been discussed.Advancedcomputer technology is well established, butadvanced CAD and information technology istruly revolutionizing the way design and analysiscan be utilized in the present, and on thechallenges to be faced in the future. It isessential that all these technologies be integratedin a controlled environment, so that we canremain successful, as we head into the 21stcentury, and the second century of poweredflight.References[1] Berry, Dennis L.Engine/Aircraft IntegrationAerodynamic Design – Boeing 777 & Beyond. TheBoeing Company, Published by AIAA, Inc., withpermission, 1997.[2] Tiegarden, Fred W., GE90 Integration with the B777 –A Success Story, Royal Aeronautical Society Paper,RAes Conference, Nottingham England, October,1992.[3] Uenishi, K., Pearson, M.S., Lehnig, T.R., Leon, R.M.CFD-Based 3D Turbofan Nacelle Design System.6103.10
PROPULSION AIRFRAME INTEGRATION DESIGN, ANALYSIS AND CHALLENGESGOING INTO THE 21st CENTURYAIAA 8th Applied Aerodynamics Conference,Portland, OR, AIAA-90-3081, 1990.[4] Norris G. Aircraft & The Environment, SilencePlease, Flight Internationl, 20-26 October, 1999.[5] Bailey, Michael W. Integrated MultidisciplinaryDesign, XIV ISABE Conference, Florence Italy,September, 1999.[6] Yaros, Steven F., McKinley, Robert E. Jr., et. al.Synergistic Airframe-Propulsion Interactions andIntegrations, NASA/TM-1998-207644, March, 1998.6103.11
Propulsion airframe integration presents unique challenges to the development of an aircraft system. Many of these challenges arise from the fact that the airframe integration issues involve major interfaces between aircraft and engine manufacturers. Good working relationships [1,2] bet
airframe supports side by side for the lengths of the airframe support that overlap. If the stabilizer foot will interfere with the previous Airframe support, turn the support 180 degrees. When installing the last airframe supports in any column,
aircraft are discussed first. Next, the key features of the aerodynamic airframe design are outlined, elucidating how a step change in noise reduction and enhanced aerodynamic performance are achieved. The evolution of the airframe design along with the characteristics of three generations of designs is briefly summarized. The airframe design
The Airframe technology development is performed within the VSR&T project. The focus herein is the Airframe technology development. (As a result of NASA’s refocus on exploration, the ISTP has been modified, and the Airframe subproject, as well as much of NGLT, has been cancelled effective the end of FY04.)
to airframe fatigue damage limitation. When delivering the material concerned with construction methods in learning outcome 2, tutors should emphasise the modular nature of the construction of the whole airframe and how the major airframe components are assembled. Examples should al
A Review of Distributed Electric Propulsion Concepts for Air Vehicle Technology 1. Introduction to DEP concept 2. DEP aircraft (CTOL, STOL, & VTOL) 3. DEP/HE system research at NASA 4. Propulsion-Airframe-Integration (PAI) effects Aero-propulsive coupling Aircraft control Noise reductions 5. R&D in electric components 6. Issues .
The aircraft propulsion system can be constructed from a number of components: propulsion groups, engine groups, jet groups, charge groups, and fuel tank systems. The NDARC propulsion group is a mechanical drive t
IMO has recognized wind assisted propulsion technology and its potential impact on energy savings and has included the effects of wind propulsion into the Energy Efficiency Design Index (EEDI) calculation in MEPC.1/Circ. 815, in which wind assisted propulsion technology is considered a method of reducing main engine power requirements.
Online Training Materials 14: Introduction to Arable Field Margins www.NPMS.org.uk Email: Support@npms.org.uk Produced by Kevin Walker for the NPMS in July 2020
