Journal of Fluids Engineering · 1977 · 91 citations · 0 references
EngineeringAerospace EngineeringAerodynamicsParametric DesignTunnel EngineeringBoundary Layer FlowBoundary-layer TheoryFlow SeparationNozzle DesignNozzle FlowWind-tunnel TestingBoundary Layer ThicknessFlow Separation CriteriaNozzle AnalysisNozzle Flow SeparationNozzle GeometryPressure Coefficients
The study compares its 2‑D contraction designs to earlier axisymmetric geometry results. The authors developed design charts for 2‑D wind tunnel contractions using inviscid flow analysis of a one‑parameter family of wall shapes defined by two cubic arcs, with inlet and exit pressure‑coefficient parameters determining shape and length, and incorporated Stratford’s separation criteria. The charts enable design of nozzles that avoid flow separation and achieve any desired exit velocity uniformity, and when inlet and exit pressure coefficients are set to just avoid separation, the exit boundary layer thickness is minimized.
Design charts for 2-D wind tunnel contractions have been developed using inviscid flow analysis, in which a one-parameter family of wall shapes, based on two cubic arcs, was investigated in detail. The design chart parameters are the maximum wall pressure coefficients at the inlet (as an indicator of the danger of separation at the inlet end) and at the exit (which is related to the exit velocity non-uniformity as well as to separation). For any choice of these two parameters the charts yield the shape parameter and the nozzle length for this particular family of shapes. The charts may be used to design nozzles with no flow separation and with any desired exit velocity uniformity. When the two pressure coefficients are chosen so that separation at both ends is just avoided, the exit boundary layer thickness should be near its minimum. Simple working forms of Stratford’s separation criteria are suggested for the prediction of separation. The results of this study are compared to those obtained earlier for axisymmetric geometries.