Modeling, Structural & CFD Analysis and Optimization of UAV

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Modeling, Structural & CFD Analysis and Optimization of UAV

  1. 1. Modeling, Structural & CFD Analysis and Optimization of UAV Dr Lazaros Tsioraklidis Department of Unified Engineering InterFEA Engineering, Tantalou 7 Thessaloniki GREECE
  2. 2. Next Generation tools for UAV’s The current paper present the usages of Hyperworks on the design of New ages Aerostructures as UAVs. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 2 reserved
  3. 3. UAV marketplace a moving target UAVs are now in service in more than 50 countries. During 2007, these aircraft logged more than 500,000 flight hours, increase bylogarithmic rate. Thousands of different aircraft in various stages of design, development or production.70 active companies and nearly 200 unique platforms enter production or currentlyunder development. Top 30 programs accounted for ~3,000 aircraft deliveries during 2008 and will deliver3,350 more during 2009 — about 93 percent of the delivery total. Over the next fiveyears, the same programs will deliver about 13,000 aircraft. Over our 2009-2018 forecastperiod, they will account for close to 65 percent of expected UAV deliveries. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 3 reserved
  4. 4. UAV’s Future “Teal Groups 2010 market study estimates that UAV spending will more than double over the next decade from current worldwide UAV expenditures of $4.9 billion annually to $11.5 billion, totaling just over $80 billion in the next ten years.” “A new study reflects the rapid growth of interest in the UAV business by increasing the number of companies covered to almost 30 U.S., European and Israeli companies, and reflect the fundamental reshaping of the industrial environment” Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 4 reserved
  5. 5. Types of UAV’s• Target drones — UAVs that simulate enemy missiles oraircraft in the demonstration and testing of antiaircraftand antiship missiles systems.• Radar decoys — Unmanned decoy aircraft deployedfrom a larger manned aircraft and designed to subvert,confuse or fool enemy radar systems.• Information, surveillance and reconnaissance (ISR)aircraft — UAVs that perform a variety of surveillance,observation and data-relay missions. For combat troopson the ground, small UAVs, including micro-UAVs(handheld/hand launched), provide “over-the-hill”scouting, to avoid ambushes and scare off insurgents.• Unmanned combat aerial vehicles (UCAVs) — Aircraftdesigned to provide unmanned weapons capabilities andsupport manned aircraft. Their capabilities include theuse of bombs and missiles, electronic warfare equipmentand directed-energy weapons. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 5 reserved
  6. 6. Hyperworks A platform for Innovation Modern FE Modeling Ultimate post processing Robust CFD solver Explore, Study, Optimize Motion Dynamic Reduce weight PA speed up projects linear and non-linear simulationsAltair Hyperworks is an engineering simulation environment which can use from engineersduring all stages of the Design and Optimization of UAVs. From design stage when the engineertests and validates new Shapes and mechanism and determine correct shapes for the engineinlet, determines optimum composite structure, reduce weight and provide more Payload. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 6 reserved
  7. 7. CFD Analysis & Optimization on UAV From Design to the Reality of Flow Challenges First 3D Design  Low Drag Cd Post Modeling for High lift CL Processing CFD Less Noise Coupling CFD Eliminate Turbulence + Shapes for Optimization Optimization code Determination of pressure distribution on the surface of the UAV that later on leads tocalculations of aerodynamics characteristics of uav such as CL, CD and CM at various angle ofattack Visualization of the airflow around the UAV using Post Processing to recognize some criticalarea with possible vortex reduction in the near future. The analytical of aerodynamicscharacteristics for various angles of attacks using CFD simulation will be conducted in this finalstage Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 7 reserved
  8. 8. High Quality meshing for CFD By using Hypermesh the total cost on human hours from Geometrycleanup to tetra mesh reduced by 60%. Special tools as Layer meshing & Refinement box option provides fastand accurate mesh for CFD analysis. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 8 reserved
  9. 9. CFD Optimization of the Wing shapeThe NACA 4412 Airfoil choose as an option for the UAV’s wing,the NACA 4412 profile provides high CL on low speed forsubsonic aircrafts.Several shapes (50) created for the optimization of the wingfor reducing the CD and increase CL, in the same time severalconstrains have to be satisfied as volume and turbulence. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 9 reserved
  10. 10. Optimized wingThe optimization of the wing create optimize performance as : Optimized Cd /Iteration Cd reduction = 35% CL increased =5% Turbulence reduction = 21% Cd Iterations Initial Optimized Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 10 reserved
  11. 11. Optimized wing on several angles of attack Lift Coefficient Analysis For each wind tunnel airspeed, the value of CL increases as the angle of attack is increased until its maximum value at around α = 35º and decreases afterwards with lower slope. Computational Fluid Dynamics (CFD) results at Mach 0.6 and 0.8 also give the same trend with maximum CL located at α = 39º and α = 35º respectively. It is observed that the value of CLmax increases as the air velocity of the wind tunnel is increased. Hence, the CL max increases with the increase of Reynolds number. This explains the difference of values of CL max between the experiments and the CFD. Drag Coefficient Analysis The variation of drag coefficient (CD) versus angle of attack (α) taken at different air speeds and Mach numbers. It is observed that the variation of drag coefficient is very slow and almost constant at low angle of attacks (below 8º). In that range of α, CD is small, below 0.03 for both experiments and CFD. As explained in the previous section, at low angle of attack, the air flow is still attached to the body and the wing. Above 8º, CD grows at higher rate as α is increased. Within this range, the wing is already in stall condition. Around 35º, a slight deflection occurs on wind tunnel experiment curves. This is where the lift coefficient reaches its maximum value. This deflection is not clearly seen on the CFD curves. Beyond this angle of attack, the drag coefficient continues to increase with almost the same slope as between 8º and 34º, and it is getting slower when α approaches 90º. From the overall curves, it is observed that higher airspeeds (or higher Reynolds number) produce higher drag coefficients. Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 11 reserved
  12. 12. Nose OptimizationThe optimization of the Nose create optimize performance as : Morph volume & Shapes Cd reduction = 18% CL increased =2% Turbulence reduction = 10% Initial Optimized Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 12 reserved
  13. 13. Engine inlet OptimizationThe optimization of the Engine Inlet create optimize performance as : Cd reduction = 10% Morph volume & Shapes CL increased =2.89% Turbulence reduction = 12% Initial Optimized Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 13 reserved
  14. 14. Conclusions of the CFD & Structural Optimization CFD Optimization Conclusions Combat Radius Max take off Increased load increased CFD Analysis & Optimization 34% 10 %  Cd Reduction : 51 %  CL Increased : 9.89 % Stabilization Problems Solved CL = Optimized Flight Load Cd = Fuel Consumption Reduction Optimized Inlet for Better Engine Performance Optimized Turbulence flow Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 14 reserved
  15. 15. Structural Analysis and Optimization Load transfer from Acusolve to Hypermesh for Linear Analysis and Optimization Data from: Angles of Attack 00, 50, 150, 200 Aerodynamic loads on the wing from extra external fuel tanks External Devices as cameras etc Linear Interpolation Pressure on the UAV surface Structural model of the UAV Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 15 reserved
  16. 16. Structural Analysis of the UAV wing Analysis  25 Loadcases (strength, pressure)  370.000 Elements  15 Material types  842 Plies  145 Laminates Aerodynamic Pressure on the wing surface Composite Structure Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 16 reserved
  17. 17. Structural Analysis of the UAV wing The UAV Wing is made by CFRP Material, several parts are assembled to create the wing. The deformation of the wing and the stresses have been calculated by using Radioss (Bulk). The traditional design of the CFRP wing provide us a heavy structureDeformation of the wing at angle of attack 00 Stresses on the wing at angle of attack 00 Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 17 reserved
  18. 18. Optimization of the CFRP wing using OptistructThe optimization of the composite wing includes theoptimization of each part composite - metalLoads : 25 loadcases (same as analysis) SkinModel : 370 000 elements (same as analysis) OptimizationObjective : Reduce Weight Metal Parts Optimal RibsSafety Constrains : Strength, stability, strain Optimizaiton Structure OptimizationManufacturing Constrains : Thickness, Stacking etc Spars Optimization Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 18 reserved
  19. 19. Optimization of the CFRP wing using Optistruct Steps of the wing skin optimization using Optistruct • Free-size optimization is used to identify the optimal ply shapes and locations of patches per ply orientation • Size optimization is used to identify the optimal thicknesses of each ply bundle • Shuffling optimization is used to obtain an optimal stacking sequence Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 19 reserved
  20. 20. Optimization of the CFRP wing using OptistructFree size optimization of the skin • Weight Reduction 32% 4 Plies with angles 0, 90, 45, -45 Thickness of each ply 4 mm Manufacturing Constrain : 00 & 900 min - 10% , max- 70% Thickness of the Ply of 00 Thickness of the Ply of 450 Thickness of the Ply of -450 Thickness of the Ply of 900 Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 20 reserved
  21. 21. Optimization of the CFRP wing using Optistruct • Weight Reduction 32% Size optimization In the second design phase, a size optimization is performed to fine tune the thicknesses of the optimized ply bundles from Phase 1. To ensure that the optimization design meets the design requirements, additional performance criteria on natural frequencies and composite strains are incorporated into the problem formulation.  Design variables: Ply thicknesses, which have been defined in the size input deck from Phase 1  Objective: Minimize the total designable volume  Constraints: •Natural frequencies (1st ~ 5th) > 0.06 KHz •Composite strains in the wing < 1800 micro-strain •Ply Thicknesses available 0,1 – 0,2- 0,3 – 0,4 mm Plies of 00 in several point Plies of 900 in several pointThickness 0.1 mm Thickness 0.25 mm Thickness 0.1 mm Thickness 0.25 mm Thickness 0.2 mm Thickness 0.3 mm Thickness 0.2 mm Thickness 0.3 mm Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 21 reserved
  22. 22. Optimization of the CFRP wing using Optistruct • Weight Reduction 32% Shuffling optimization Shuffling optimization is used to obtain an optimal stacking sequence  Design variables: Stacking seguence  Objective: Optimize the stacking seguence  Constraints: 1) The maximum successive number of plies of a particular orientation does not exceed 4 plies. 2) The + 45s and – 45s are reversed paired Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 22 reserved
  23. 23. Optimization using OptistructOptimization ConclusionsComposite Parts Optimization Total Weight Reduction 38 % Stiffness Increased 12% Optimized Initial Stresses Decreased 30 % Deformation Decreased 15% 39 % 32 % 25 % 22 % Main Wing fuseland Fuse skin structure Sub structures Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 23 reserved
  24. 24. Optimization of other parts Overall Structure Optimization  198 Parts Optimized with Optistruct  124 Composite parts  23 Connections simulated and optimized  New material and technologies as Nanotubes in composites tested  Manufacturing constrains increase manufacturing time more than 30%  Thermal loads from the engine was simulated  24 Different maneuvers loads tested  Total time for Development reduce by 40%  Topology Optimization used for Ribs  Topology Optimization used for Internal structure  Turbulence loads during take off and landing that would cause issue eliminated at the stages of development Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 24 reserved
  25. 25. Optimization using Acusolve & OptistructOverall Payload PayloadConclusions 450 Kg 260 Kg Combat Radius Increased by 45% Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 25 reserved
  26. 26. Thank you InterFEA EngineeringInnovative Engineering Solutions Tantalou 7 Thessaloniki GREECE info@interfea.com Copyright InterFEA Engineering Inc. Proprietary and Confidential. All rights 26 reserved

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