Topic
Diffuser (thermodynamics)
About: Diffuser (thermodynamics) is a research topic. Over the lifetime, 6731 publications have been published within this topic receiving 54738 citations.
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TL;DR: In this article, the isothermal compression of a gas by a liquid jet in a mixing throat followed by secondary compression in a diffuser is described by a one dimensional model including frictional losses.
Abstract: The isothermal compression of a gas by a liquid jet in a mixing throat followed by secondary compression in a diffuser is described by a one dimensional model including frictional losses. Good theory-experiment agreement is shown; pump efficiencies can exceed 40 percent. Mixing throat and diffuser energy analyses are presented. The isothermal compression mechanism in the throat is related to momentum transfer while the diffuser process consists of a pistonlike compression of entrained gas bubbles by the continuous liquid medium. The efficiency of a liquid-jet gas pump depends primarily on the mixing loss. The mixing loss function, the throat compression ratio and the Mach number are developed as functions of the throat inlet velocity ratio v and the jet pump number n. A zero mixing loss criterion defines the theoretically possible region of pump operation. Design applications are discussed.
56 citations
Patent•
19 May 1995TL;DR: In this paper, the authors proposed a surge detection device in combination with fluid flow guide vanes and blades of a turbomachine, which enables full utilization of the potential capability of the turbomachines.
Abstract: A turbomachine having variable-angle diffuser vanes operates by regulating the angle of the diffuser vanes on the basis of the sensors disposed on the pump body or pipes of a surge detection device. The onset of surge can be forecast by measuring the fluctuations in the operating parameter(s) over a measuring interval of time computed on the basis of the operating characteristics of the impeller of the turbomachine. The onset of surge is prevented by adjusting the angle of the diffuser vanes in accordance with the sampling duration for parameter fluctuations over the measuring interval of time, and by adjusting the diffuser vanes to maintain the operating parameter fluctuations of the fluid machinery below a threshold value of the turbomachine derived from the design flow rate of the turbomachine. Application of the surge detection device in combination with fluid flow guide vanes and blades of the turbomachine enables full utilization of the potential capability of the turbomachine.
56 citations
Patent•
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23 Sep 1985
TL;DR: In this article, the axial fan discharge velocity is slowed in the short diffuser sections where diffuser vanes also block rear noise radiation, and further noise reductions can be provided by inlet sound baffles, outlet acoustic diffuser splitters, and acoustic absorption materials in the inlet and short, rear axial diffuser short sections.
Abstract: A fan assembly provides for the compact and efficient movement of ambient air in areas requiring very low noise generation. In this new configuration, stationary turning vanes are placed at the air inlet followed by a sound cell, axial discharge fan and short axial (vaned) diffuser splitter sections. The stationary turning vanes induce a predetermined air rotation which provides a smooth rotating air flow into the rotating fan blades. The stationary turning vanes also block radiated noise from discharge through the air inlet and support the fan motor. The fan blades impart an opposite rotational momentum just sufficient to obtain an axial or nearly axial velocity discharge increment. The resulting axial fan discharge velocity is slowed in the short diffuser sections where diffuser vanes also block rear noise radiation. The slowed but pressurized air can now enter into an air distribution system with significantly reduced fan generated noise. Further noise reductions can be provided by inlet sound baffles, outlet acoustic diffuser splitters, and acoustic absorption materials in the inlet and short, rear axial diffuser short sections.
55 citations
TL;DR: In this article, an experimental analysis of the unsteady phenomena developing in a vaneless diffuser of a radial flow pump was presented, and the influence of these phenomena on the diffuser efficiency was also investigated.
Abstract: This paper presents an experimental analysis of the unsteady phenomena developing in a vaneless diffuser of a radial flow pump. Partial flow operating conditions were investigated using 2D/3C high repetition rate PIV, coupled with unsteady pressure transducers. Pressure measurements were acquired on the shroud wall of the vaneless diffuser and on the suction pipe of the pump, whereas PIV flow fields were determined on three different heights in the hub to shroud direction, inside the diffuser. The classical Fourier analysis was applied to both pressure signals to identify the spectral characteristics of the developing instabilities, and the high-order spectral analysis was exploited to investigate possible non-linear interaction mechanisms between different unsteady structures. A dedicated PIV averaging procedure was developed and applied to the PIV flow fields so as to capture and visualize the topology of the spectrally identified phenomena. The influence of these phenomena on the diffuser efficiency was also investigated.
55 citations
TL;DR: Optization of the vane shape, in the absence of manufacturing and stress constraints, led to a nearly 8% reduction in the total pressure losses compared to the baseline design by reducing the base separation.
55 citations