An experimental investigation of a wall jet in a torus

Results of an experimental investigation of the velocity profile of a turbulent gas injected in a toroidal configuration are presented. The measurements surprisingly show that it is possible to describe the radial distribution of the azimuthal velocity in terms of a plane wall jet discharging in an external stream. The growth of the inner boundary layer, the width of the jet, and the velocity profile are in accordance with the known experimental data on this subject. A fundamentally different relation has been deduced for the decay of the maximum velocity. Up to now Sigalla's formula \(U_m /U_j \propto \sqrt {a/x}\) is generally accepted. Our data based on an essentially extended range of x/a, correlate with the exponential relation $$U_m /U_j = exp\left { - 154(Re_x )^{ - 0.777} \frac{x}{a}} \right].$$