March 18-20, 2013 THE EFFECTS OF THE PLANFORM SHAPE ON DRAG POLAR CURVES OF WINGS: FLUID-STRUCTURE INTERACTION ANALYSES RESULTS Authors: M.R. Chiarelli, M. Ciabattari, M. Cagnoni, G. Lombardi Speaker: Aerospace Engineer Matteo CIABATTARI matteo.ciabattari@gmail.com
Relationship between Critical Conditions and the component U cosλ
The reaction moments and stress values at the root of the curved wing are reduced by about 5% - 8 % Abstract AEROELASTIC ANALYSES OF TWO HALF WING MODELS: CURVED AND SWEPT PLAN - FORM The curved plan-form causes a variable angle of sweep along the wing span, so, in the transonic flight conditions wave drag effects are strongly reduced The effects of the plan-form shape on drag polar curves (fixed values of CL) leads to the reduction of CD of 7% - 10% The curved plan-form configuration improves the wing s aeroelastic behavior : Analyses have been carried out by using STAR - CCM+ 6.04.14 and Abaqus 6.11 in co - simulation
Index 1. Introduction 2. Rigid wing s model : STAR - CCM+ 6.04.14 CFD analyses 3. Elastic wing s model : Fluid - structure - interaction (FSI) analyses STAR - CCM+ 6.04.14 and Abaqus 6.11 co - simulation 4. Detailed analysis of rigid and elastic models results 5. Conclusions and future research activity
1.Introduction: Wings characteristic geometry Half wing area (S) = 239 m 2 Aspect ratio (AR) = 7.53 Taper ratio (λ) = 0.119 Dihedral angle = 0 Leading edge equation y = -13316 x 2 + 43519 x + 166 Supercritical airfoil lies on planes parallel to the longitudinal plane of the wing half models Supercritical airfoil NASA SC(02) 0410 Not twisted airfoils along the half span
Volume of the aerodynamic field built in Catia V5 R20 300,000 hexahedral cells around the wing 100,000 free cells in the far field 2. Rigid wing s model : STAR - CCM+ 6.04.14 CFD analyses
2. Rigid wing s model : STAR - CCM+ 6.04.14 CFD analyses Settings of the CFD model in STAR-CCM+ 6.04.14 Properties standard air H = 10,000 m Density ρ = 0.4135 kg/m 3 Static temperature T = 223.15 k Static pressure p = 26,500 Pa Kinematic viscosity ν = 0.92 10-5 m/s 2 Physic model set into STAR-CCM+ 6.04.14 Space Three Dimensional Motion Stationary Time Steady Material Gas Flow Coupled (Momentum and Energy) Equation of State Ideal Gas (Compressible) Viscous Regime Turbulent Reynolds-Averaged Turbulent k-ε Model
CFD analysis results between the two rigid wing models (CL= 0.4) 200 hours of CPU simulation ( 2 dual core personal computer with 8 GB RAM each one)
CFD analysis results between the two rigid wing models (CL= 0.4) MACH CD RIGID CURVED WING CD RIGID SWEPT WING ΔCD % 0.8 0.024 0.025-4 0.85 0.026 0.029-10 0.875 0.029 0.035-17 0.9 0.036 0.045-20
3. Co-simulation : STAR-CCM+ 6.04.14 and Abaqus 6.11 The CFD model and the FEM structural model must be perfectly complementary in the areas where take place the exchange of the nodal forces and the displacement nodal values: in Catia V5 R20 an aerodynamic field that surround the wing is constructed (slide n. 6) Structural model of swept and curved wing has been built by using Catia V5 R20 Structural properties and dimensions have been assigned to the components (SKIN, STRINGERS, RIBS, SPARS) in Abaqus 6.11 Both models have the same dimensions for all their characteristic components The results (static Aeroelastic analyses) do not take into account the distributions of the structural or not structural weight: little influence on the deformation shape of the wing at the examined flight conditions
3. Co-simulation : STAR-CCM+ 6.04.14 and Abaqus 6.11
3. Co-simulation : STAR-CCM+ 6.04.14 and Abaqus 6.11
3. Co-simulation : STAR-CCM+ 6.04.14 and Abaqus 6.11 MATERIAL PROPERTIES (AL 7075) DENSITY [kg/m 3 ] 2,700 YOUNG MODULUS [MPa] 71,000 POISSON MODULUS 0.3 MASS OF THE HALF WING STRUCTURE [kg] CURVED WING 10,203 SWEPT WING 10,125 NUMBER OF STRUCTURE MESH ELEMENTS CURVED WING 1,456 SWEPT WING 1,525
Set in the CFD code STAR-CCM+ 6.04.14 an implicit unsteady analysis 500 hours of CPU co - simulation to obtain these results
Set in the CFD code STAR-CCM+ 6.04.14 an implicit unsteady analysis 500 hours of CPU co simulation to obtain these results
FLIGHT CONDITIONS : H = 10,000 m ; MACH = 0.85 ; CL = 0.4 ELASTIC CURVED WING CD PRESSURE CD SHEAR CD TOT NOSE 0.0081 0.0006 0.0087 UPPER SURFACE 0.0164 0.0019 0.0183 LOWER SURFACE -0.0015 0.0017 0.0002 Tot 0.0230 0.0042 0.0272 ELASTIC SWEPT WING CD PRESSURE CD SHEAR CD TOT NOSE 0.0111 0.0005 0.0116 UPPER SURFACE 0.0158 0.0018 0.0176 LOWER SURFACE -0.0015 0.0016 0.0001 Tot 0.0254 0.0039 0.0293 ΔCD PRESSURE % ΔCD SHEAR % ΔCD TOT % NOSE -27.0 20-25.9 UPPER 3.8 5.6 4 LOWER 0 6.2 0 Tot -9.4 7.7-7.2
The intensity of the shock wave on the curved wing is lower than the intensity of the shock wave on the swept wing Retardation of the boundary layer separation and an increase of aerodynamic efficiency (E = L/D) of the wing
A comparison of the in plant shape and position of the wave front on the two wings upper surface
A comparison of the in plant shape and position of the wave front on the two wings upper surface
FLIGHT CONDITIONS : H = 10,000 m ; MACH = 0.85 ; CL = 0.4 Front view: supersonic zone on the upper surface of the two wings The sonic boundary, the red surface which enclose the supersonic region around the wing, has a different shape and different dimensions comparing the swept wing with the curved wing, especially toward the tip of the two wings
FLIGHT CONDITIONS : H = 10,000 m ; MACH = 0.85 ; CL = 0.4 Rear view: supersonic zone on the upper surface of the two wings The sonic boundary, the red surface which enclose the supersonic region around the wing, has a different shape and different dimensions comparing the swept wing with the curved wing, especially toward the tip of the two wings
4. Detailed analysis of rigid and elastic model results The Elasticity effects lower values of CL for fixed value of angle of attack
4. Detailed analysis of rigid and elastic model results The Elasticity effects lower values of CD for fixed value of angle of attack
4. Detailed analysis of rigid and elastic model results The drag polar curves CL - CD are quite similar for the two model elastic and rigid wing The CD 0 value (drag coefficient corresponding to zero value of the lift) is not influenced by the deformation effects, due to the reduction of the aerodynamic loads along the span of the two wings
4. Detailed analysis of rigid and elastic model results The estimated distribution of the aerodynamic load along the half span for the two elastic wings: the resultant lift for the curved wing tends to move inwards and this causes the reduction of moment characteristics at the root of the wing box.
4. Detailed analysis of rigid and elastic model results The results by the structural FE models of wings: at the clamped section for the curved wing model the stresses are less of 5 % than the swept wing model. It depends on the reduction of both the bending and torque moment at the root of the wing.
5. Conclusion Also taking into account the elasticity effect of the wing - box structure the curved plan-form of a wing favorable influences both CP and MACH distribution along the wing span The results discussed in the present paper agree with previous results published by the authors and confirm that the feasibility of the examined novel wing configuration can be reach adopting standard design technology Flight conditions: H = 10000 m ; CL =0.4 ; MACH = 0.85 The curved wing shows a reduction of CD of 7% than the swept wing The structural bending moment and torsion moment of curved elastic model are less of 5% : the stresses in the skin of the curved wing are less of 5%
5. Conclusion The pressure rise across the shock wave is less intense and smoother in the curved wing. The adverse pressure gradient towards the trailing edge is reduced. The separation of the boundary layer of the curved wing is delayed with respect to the swept wing in transonic regime, with consequent beneficial effects on the drag ( the aerodynamic efficiency tends to increase)
5. Conclusion The plant shape of the shock wave front is strongly influenced by the shape of the wings
5. Conclusion The shape and dimensions of the supersonic zone around the wing (the bubble zone) are strongly influenced by the shape of the wing: the perturbation of the curved wing is less intense and then the energy dissipated in the transonic phenomena around it reduces at same values of CL and MACH of flight Within the limits of a comparative study the result obtained confirm that, also adopting a fluid - structure interaction procedure (FSI), the effects of the curved plan-form configuration of a wing is not negligible from the aerodynamic point of view in the transonic regime.
Thanks to the Co-simulation by using STAR-CCM+ 6.04.14 and Abaqus 6.11 It has been possible to examine with a good level of reliability a complex Aeroelastic phenomena with minimum computational resources : Only two Personal Computer with 8 GB of Ram each one Future research activity Dynamic response analyses ( Flutter Behavior) by using FSI analysis procedure : Co - simulation by using STAR-CCM+ 6.04.14 and Abaqus 6.11
THE END (For the moment...) Thank you Prof. Eng. Mario Rosario CHIARELLI ( - University of Pisa, Italy) phone number:+390502217253 e-mail: chiarelli@dia.unipi.it Speaker: Aerospace Eng. Matteo CIABATTARI phone number :+393284771319 e-mail: matteo.ciabattari@hotmail.com or matteo.ciabattari@gmail.com