Drag reduction in pipe flow using microbubbles and acoustic energy

Abstract

Methods and apparatus for reducing drag in fluid flow through pipes that utilizes microbubbles and acoustic energy are provided. A gas ejector for microbubble generation in a pipe is provided and includes a pipe comprising a wall having inner and outer diameters and at lease one orifice in the wall for ejecting gas microbubbles into the pipe. To cause the formation of the microbubbles, a flow restrictor is provided in the pipe, with the flow restrictor being spaced from the inner diameter of the pipe wall and positioned adjacent the at least one orifice. The flow restrictor causes and increase in the velocity of the fluid in the pipe past the at least one orifice, and produces a pressure drop which draws gas into the orifice. That gas is then ejected into the pipe in the form of microbubbles. Acoustic energy may be used to provide further reductions in drag.