Experimental study of the effect of tangential swirling injection on diffuser effectiveness

The experimental data on studying the tangential swirling injection effect on the effectiveness of a conical diffuser with an aperture angle of $18^{\circ}$ and the expansion ratio equal to four are presented. It has been indicated that the effect becomes maximal for a given diffuser at an insignificant initial thickness of the boundary layer, when the injected jet swirling angle is $15^{\circ}$ and the relative injection rate is $7.7\%$, as a result of which the pressure increases from $0.48$ to $0.79$ if the injected jet energy is taken into account.