讲义参考教案08-optimate propellercase

1、Optimization of a propeller in tunnelSTAR-CCM+ / OPTIMATECarlo Pettinelli CD-adapco TorinoIntroductionA simplified tunnelled-propeller model is parametrized inside CADNo gapsNo curvature on leading and trailing edgeIn this example the 3D-CAD model within STAR-CCM+ was usedFixed: # of blades, RPM = 5

2、00 , hub and tunnel size3 Objectives Maximize ThrustMinimize TorqueWater Speed minimumStagnationInflow P=0P=0Parameters3 sections with customizable cordand positionEach profile has camber, % of max camber along lengthThickness was kept constant throught, but could be variedTotal of 14 geometrical va

3、riables, with given rangesSetup 1/4Choose the type of explorationUse optimization to reduce design spaceUse DoE /DE later for refiningSetup 2/4Transfer a subset of the parameters from the 3DCAD to the Optimate panelChoose the rangeSetup 3/4Define objectives, if necessary also constraintsChoose outpu

4、t Plots & ScenesSetup 4/4Define number of runsChoose how to use processors Baseline testcase200 K trim cellswith prism layersGood convergenceof mass flow, torque and Thrust in 400 iterFirst 120 props.Evolution (Pressure on suction side )“Last Generation” Designs.Clear trend towards “C” shape, small

5、tipReverse “C” show broader tipTorque / Thrust Pareto FrontEvolution towards the front (compromise of Thrust/ Torque/ MF)All design (400) ID 400ID 397Thrust / MF Pareto FrontDue to strong physical correlation the margin to reduce mass flow are very small 3D Pareto surfaceDue to strong correlation be

6、tween Thrust and MF, the 3D Pareto surface is close to a line Analysys : camber and eccentricitylowest profile needs high camber and high eccentricityMid profile also required ecc close to .7Analsys : camber and eccentricityChord of lowest profile has “two families”Transversal shift has clear patter

7、 to “c” shapeHighest profile has small cordAnalysis: angle of incidenceAverage AoA are respectively 16.5 / 20 / 6 for base/mid/tipLarge spread of values on tip, very low on mid, moderate at base basemidtipTHRUST: Single objective OptimizationPareto Optimization test has shown variables sensitivities

8、Helps restrict the range or reduce variablesNew test with the single objective of maximizing thrust, given a threshold on power used.Restrict variable to profile lengths and skew (angle) Profile shapes and AoA fixedTwo different hypothesis on max power: 2 and 4 KWattLow Power CaseConvergence of best

9、 designsLow Power CaseTORQUE vs THRUSTHigh Power SolutionOnly marginal thrust increase achieved by doubling the powerConstraints probably too strongHigh Power SolutionConclusionsSTAR-CCM+ and Optimate can be used effectively to exploring large design spaces Various types of explorations are possible: Pareto, Single Objective, DoEEase of use and speed of setup, no par