Abstract: A throttling valve that has an outer ring unit having a plurality of superimposed cylindrical shaped outer throttling rings that define a series of annular passages between the rings. An inner ring unit also having a plurality of superimposed cylindrical shaped inner throttling rings is adapted to movably support the inner rings within the annular passages to establish elongated flow orifices between the adjacent surfaces of the rings. The geometry of each orifice is arranged so that the fluid in transit remains attached to the control surfaces of each orifice and to insure that the static pressure along the length of the orifice remains above the dynamic pressure. The tip region of each orifice is provided with a diverging flow section to further insure quiet performance along the entire length of the orifice.