Flow Predictions for Multi-Element Control Surfaces
Final rept. 1 Jan 2000-30 Sep 2001
NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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The TAC Tab-Assisted Control and FlexTAC Flexible Tab-Assisted Control airfoils based on NACA 0018 sections are conceptual multi-element airfoil designs for future marine vehicle control surfaces. In addition to a relative motion between the stabilizer and the flap, either a rigid for TAC or a flexible for FlexTAC tab is used to augment the functionality of the control surfaces. The TAC airfoil has a front and a rear gap while FlexTAC airfoil has only the front gap. This report summarizes CFD validations on the TAC and FlexTAC airfoils using unstructured Reynolds Averaged Navier Stokes RANS solvers, i.e. UNCLE and CRUNCH codes. The force and moment predictions are compared with the 24- inch water-tunnel test data obtained for the TAC airfoil and the 36-inch water-tunnel data obtained for the FlexTAC airfoil. The CFD results suggest that the UNCLE and CRUNCH codes are able to predict the forces and moments with reasonable accuracy for flap angles under 20 degrees. The comparisons also indicate that the FlexTAC measured force data may have been over-corrected for the water-tunnel blockage. Comparisons between the measured TAC data and FlexTAC data imply that the gudgeons installed for the TAC experiments have a profound effect on the stabilizer and flap torque calculations, but have a minimum effect on the force calculations.
- Fluid Mechanics