Analytical Study of Ventilated Wind Tunnel Boundary Interference on V/ STOL Models Including Wake Curvature and Decay Effects
Final rept. Feb-Oct 1973
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN
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The wind tunnel boundary interference on a VSTOL model is calculated in a rectangular test section with solid vertical walls and ventilated perforated or slotted horizontal walls. The interference is found by applying the small perturbation theory of an incompressible fluid to the boundary value problem. The theory uses an image method in addition to Fourier transforms with an equivalent homogeneous boundary condition on the ventilated wall. The mathematical representation of the VSTOL model accounts for the curvature and decay of the wake. The assumption of a constant wake strength produces a paradox in that the maximum value of the interference factors increases as the initial jet velocity decreases. The most significant aspect of the analysis shows that nonlinear cross-flow effects at the tunnel boundary are important in the VSTOL case, and a quasi-linear approximation to these effects is introduced into the solution providing good agreement with experimental data.
- Test Facilities, Equipment and Methods