Abstract: A cleaning apparatus and method is disclosed which utilizes a nozzle generally comprising a cylindrical drum having external and internal air chambers, each of which terminates in a pipe having a rectangular cross-section. One of the pipes has a smaller cross-section than the other, and is disposed within the larger pipe. A high-pressure water pipe is concentrically disposed along the longitudinal axis of the smaller pipe. The space between the two pipes defines a passageway for a stream of compressed air which shapes the stream of water emanating out of the center of the smaller pipe into a jet of water having a bar-shaped cross-section, and a uniform pressure gradient at all points across this cross-section. The smaller pipe is provided with a symmetrical array of apertures for shunting part of the air stream flowing between the two pipes in a radial direction toward the pressurized stream.