| 摘要 |
A swivelling joint for a multifunction pressure probe comprising flexible conduits connecting external pressure capture orifices and internal pressure measurement receptors. The joint is shown in section in Figure 1. It comprises a fixing base equipped with a bearing, a mobile pallet rotating freely on a limited displacement and provided with a foot pivoting in the bearing of the fixing base, pressure capture orifices located on the mobile pallet and pneumatic conduits linking them to pressure measurement receptors by passing through the foot of the mobile pallet and the fixing base. The joint comprises a plate rotating relative to the food of the mobile pallet fixed under the fixing base on the same axis as and separated from the bearing of the mobile pallet and pieces of flexible tubing, located symmetrically with respect to the axis, which connect the foot of the mobile pallet to the plate and form the pneumatic conduits running from the foot of the pallet to the plate, beyond with the pressure measurement receptors are located. The joint additionally comprises electrical wires placed symmetrically with respect to the axis and close to it. The joint comprises a system for measuring the angular position of the probe with means for correcting the error arising from the elastic stiffness estimated by the relationship alphaapproximatelyn - alpha = ((alpha - alpha0)R)/kV2, where V is air speed, kV2 is the coefficient of aerodynamic return, alpha0 is the neutral position of the pallet and R the coefficient of stiffness or by the relationship alphaapproximatelyn - alpha = K((alpha - alpha0)/(Pt - Ps)), where K is a wind tunnel measured coefficient, Pt is total pressure and Ps is the static pressure.
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