Diffuser (thermodynamics)

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

Numerical Calculations of the Flow in Annular Combustor Dump Diffuser Geometries

Abstract: A method for calculating the turbulent isothermal flow in axisymmetric annular dump diffuser geometries is described and appraised. The calculation method is based on the numerical solution of the time-averaged transport equations for momentum, continuity, turbulence kinetic energy and energy dissipation, using a finite difference formulation. A boundary-fitted curvilinear orthogonal grid obtained from a solution of the inverse Laplace equations is used to represent the curved combustor head accurately and reduce numerical diffusion errors due to better alignment of the flow streamlines with the grid lines. Comparison between predicted results and measurements indicates that variations in (a) the overall pressure recovery and (b) the loss coefficient performance of the dump diffuser system, with changes in diffuser design features (for example inner/outer annulus mass flow split or dump gap), can be predicted to within 7 per cent of the inlet dynamic head without adopting a more refined turbulence closure...

Oscillating flow in a 2-D diffuser

Abstract: Separating oscillating flows in an internal, adverse pressure gradient geometry are studied experimentally. Simultaneous velocity and pressure measurements demonstrate that the minor losses associated with oscillating flow in an adverse pressure gradient geometry can be smaller or larger than those for steady flow. Separation is found to begin high in the diffuser and propagate downward. The flow is able to remain attached further into the diffuser with larger Reynolds numbers, small displacement amplitudes, and smaller diffuser angles. The extent of separation grows with L 0/h. The minor losses grow with increasing displacement amplitude in the measured range 10 < L 0/h < 40. Losses decrease with increasing Re δ in the measured range of 380 < Re δ < 740. It is found that the losses increase with increasing diffuser angle over the measured range of 12° < θ < 30°. The nondimensional acoustic power dissipation increases with Reynolds number in the measured range and decreases with displacement amplitude.

Plural turbochargers having a common exhaust housing

Abstract: The twin exhaust-gas-powered turbines (9, 10) driving intake air compressors (1, 2) for an internal-combustion engine are connected together and mounted on central support brackets (47, 48) by a common turbine discharge housing (20) that deflects the discharge of each turbine separately towards an outlet funnel (24) with the help of a guiding structure that contains a median wall (33). Diffuser horns (31, 32) and hollow central plugs provide, in a short axial distance, for establishing a static pressure for causing the gas to flow with uniform pressure distribution out through the discharge funnel (24). The latter portion of the outflow path is enlarged by side pieces (26, 27) fitting over holes in the central piece (20) of the discharge casing through which the diffuser horns (31, 32) protrude with ample spacing from other components. The static pressure just mentioned creates a back pressure that improves the efficiency of the turbo-superchargers in their extraction of dynamic energy from the exhaust gas stream. The air compressors are provided with a "floating" suspension from brackets (49, 50) that is tolerant of thermal expansion.

Turbocompressor and refrigerating machine

Abstract: The invention is aimed at making a space necessary for installing an adjusting mechanism for a diffuser small to thereby miniaturize a turbocompressor as well as a refrigerating machine where this turbocompressor is a constituent element. A compressor incorporating a diffuser 34 adopts an adjusting mechanism comprising; a diffuser ring 37 forming one wall 34 a, arranged so as to be a concentric circle with the surroundings of a second stage impeller 17 b and supported on a casing 25, and which can be rotated in the circumferential direction and which can be moved in an axial direction of the second stage impeller 17 b, with a groove 37 a formed on an outer peripheral face at an incline to the axial direction of the second stage impeller 17 b; a protrusion 40 provided on the casing 25 and fitted into the groove 37 a; a shaft 38 axially supported on the diffuser ring 37; and a drive section 39 for driving the shaft 38 in a lengthwise direction.

Air diffuser for combustor

Abstract: A system includes a multi-tube fuel nozzle of a turbine combustor. The multi-tube fuel nozzle includes a support structure defining an interior volume configured to receive an air flow; a plurality of mixing tubes disposed within the interior volume, wherein each of the plurality of mixing tubes comprises a respective fuel injector; and an outer annular wall configured to direct an air flow from an annulus between a liner and a flow sleeve of the turbine combustor at least partially radially inward into the interior volume through an air inlet and toward the plurality of mixing tubes, wherein the outer annular wall at least partially defines an air flow passage extending from the annulus to the interior volume.