SUMMARYThis report presents an experimental investigation of the mean properties of turbulent, three-dimensional, incompressible air jets issuing into a quiescent air ambient from various rectangular orifices parallel to, and at the surface of, a flat plate. An analytical approach to estimate the shear stress distribution at the plate is also presented.The flow field of a three-dimensional wall jet is found to be characterized by three discinct regions in the axis velocity decay.From the results obtained it is concluded that for three-dimensional wall jets the maximum velocity in the flow in the near field exhibits a decay rate dependent on orifice geometry, while far downstream of the jet exit it decays at the same ra 4 .e as that in a radial wall jet flow field independent of orifice geometry.Furthermore, it is shown that the growth of the mixing layer normal to the plate is apparently independent oZ orifice shape while the near field spanwise growth is affected by initial geometry.
An experimental investigation of heated three-dimensional turbulent free jets is presented. Emphasis is placed on the basic character of such flows and their relation to their unheated counterparts and to heated axisymmetric jets. Temperature and velocity distributions indicate that these flow fields may be characterized by three distinct regions in terms of the axis decays: a potential core region where axis values are close to the exit values, a characteristic decay region wherein the axis decays are dependent upon orifice geometry, and an axisymmetric decay region where the axis decay is axisymmetric in nature and thus independent of orifice geometry. These regions are not exactly the same for temperature as for velocity, the former being shifted somewhat upstream of the latter. Half-width data indicate that heated three-dimensional jets change shape as they proceed downstream, ultimately becoming axisymmetric in nature, regardless of initial orifice shape. Profile characteristics and similarity are discussed as well as cross-plane contours of pertinent flow variables. Some of the effects of initial conditions and exit flow quality on the subsequent development of three-dimensional jets are shown and the sensitivity of such flows to these factors is described.
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