Diffuser (thermodynamics)

About: Diffuser (thermodynamics) is a research topic. Over the lifetime, 6731 publications have been published within this topic receiving 54738 citations.

Liquid Jet Pumps for Two-Phase Flows

Abstract: Isothermal compression of a bubbly secondary fluid in a mixing-throat and diffuser is described by a one-dimensional flow model of a liquid-jet pump. Friction-loss coefficients used in the four equations may be determined experimentally, or taken from the literature. The model reduces to the liquid-jet gas compressor case if the secondary liquid is zero. Conversely, a zero secondary-gas flow reduces the liquid-jet gas and liquid (LJGL) model to that of the familiar liquid-jet liquid pump. A ``jet loss`` occurs in liquid-jet pumps if the nozzle tip is withdrawn from the entrance plane of the throat, and jet loss is included in the efficiency equations. Comparisons are made with published test data for liquid-jet liquid pumps and for liquid-jet gas compressors. The LJGL model is used to explore jet pump responses to two-phase secondary flows, nozzle-to-throat area ratio, and primary-jet velocity. The results are shown in terms of performance curves versus flow ratios. Predicted peak efficiencies are approximately 50 percent. Under sever operating conditions, LJGL pump performance curves exhibit maximum-flow ratios or cut-offs. Cut-offs occurs when two-phase secondary-flow steams attain sonic values at the entry of the mixing throat. A dimensionless number correlates flow-ratio cut-offs with pump geometry and operating conditions.more » Throat-entry choking of the secondary flow can be predicted, hence avoided, in designing jet pumps to hand two-phase fluids.« less

Exhaust diffuser for axial-flow turbine

Abstract: An axial-flow turbine has an exhaust diffuser including a hub-side tube and a tip-side tube. In the exhaust diffuser, front struts and rear struts are placed to cross a flow of working fluid. A wake generated behind the front strut diverts from the rear strut and passes through a gap between a pair of the rear struts. Otherwise, a wake generated behind the front strut hits against the front face of the rear strut. The front struts are equal to or multiple of the rear struts in number.

Lighter than air wind energy conversion system utilizing an external radial disk diffuser

Abstract: A lighter-than-air (LTA) wind energy conversion system (WECS) wherein the gas-filled LTA envelope carries a main rotor and electrical generator to take advantage of high wind speeds available at high altitudes. The LTA envelope is tethered to a ground based mooring system designed to provide self-orientation for the LTA envelope. In a preferred embodiment, heavy mechanical transmissions are eliminated by providing a radial disk diffuser within the LTA envelope coupled through a drive shaft to a wind-driven external rotor. Rotation of the rotor-diffuser drives an induction turbine positioned within the gas inlet to the diffuser, the lifting gas for the envelope also serving as the working fluid for the turbine. The output of the induction turbine is coupled to an electrical generator whose output is, in turn, transmitted to the ground via the tethering system.

Rotating vane diffuser for a centrifugal compressor

Abstract: A vaned diffuser for a centrifugal compressor has provision for selectively adjusting the pitch of the vanes in order to accommodate variable load conditions. Each of the vanes is rotatable about a pivot pin near its leading edge and is engaged with an actuation member near its trailing edge. The actuation members are attached to a common ring which can be selectively rotated to move to the vanes in unison. The ring is supported by rollers at its outer periphery and is positioned at the outer periphery of a diffuser wall such that there is no forward facing step projecting into the flow stream.