Fluids mixing apparatus

In apparatus for introducing a first fluid into a second fluid, said apparatus having a shaft which extends into said second fluid, an impeller on said shaft, said shaft and impeller having a passageway for said first fluid which extends through said shaft and said impeller into communication with said second fluid, the improvement which comprises a pumping impeller comprising a blade having a cross-sectional profile which defines an airfoil with a suction surface and a pressure surface on opposite sides thereof, said airfoil blade having a camber, a leading edge and a trailing edge which defines a chord therebetween, said camber having a maximum length in the range of about 2% to 6% of the length of said chord, the location of said maximum camber length being measured between the midline of said blade and said chord along a perpendicular to said chord in a region measured along said chord a distance of in a range about 20% to 60% away from said leading edge toward said trailing edge, the maximum thickness of said blade between said pressure and suction surfaces being in a range from about 10% to 18% of the length of said chord, and the portion of said fluid passageway in said impeller comprising a hole, extending through said suction surface in and only in a region of said suction surface located between perpendiculars from said chord to said suction surface in a range from about 60% to 80% of the length of said chord along said chord from said leading edge toward said trailing edge, the axis of said hole being perpendicular to said suction surface.