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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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Patent
08 Jul 1992
TL;DR: In this paper, the authors describe an environmental control system for conditioning air in a vehicle compartment, such as an aircraft cabin, which includes an inlet section, an outlet section, a diffuser section and a mixing section.
Abstract: An environmental control system for conditioning air in a vehicle compartment, such as an aircraft cabin. Cool expanded higher-pressure air from a turbine is mixed with recirculated warmer, lower pressure air from the compartment. The air is mixed and recirculated by a jet pump which includes an inlet section, an outlet section, a diffuser section and a mixing section. The mixing section includes a plurality of separate mixing chambers. The diffuser section includes diffusers for receiving mixed gases from each of the mixing chambers. The outlet section receives the mixed gases which are then conveyed to the compartment. The inlet section includes for each of the mixing chambers, a primary nozzle for introducing the higher-pressure air into a respective mixing chamber, and a secondary nozzle for introducing the lower pressure air to a respective mixing chamber.

143 citations

Journal ArticleDOI
TL;DR: In this article, two-dimensional and three-dimensional, unsteady state Reynolds-averaged Navier-Stokes (RANS) equations with standard k-e turbulence models were solved within an entire stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes.
Abstract: Two-dimensional and three-dimensional, unsteady state Reynolds-averaged Navier-Stokes (RANS) equations with standard k-e turbulence models were solved within an entire stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes. A complete solution of transient flows due to the interaction between components in the whole pump without approximating the blade count ratio of impeller to diffuser was obtained by employing an Arbitrary Sliding Mesh. The unsteady numerical results were compared with experimental data and values calculated by the singularity method

133 citations

01 Jan 2002
TL;DR: In this paper, the authors used airflow modeling and particle tracking methodologies to compare the risk of contaminant deposition on an operating room (OR) surgical site and back table for different ventilation systems.
Abstract: This paper uses airflow modeling and particle-tracking methodologies to compare the risk of contaminant deposition on an operating room (OR) surgical site and back table for different ventilation systems. The ventilation system designs considered incorporated commonly used diffuser types, in particular, conventional, laminar, nonaspirating, and displacement diffuser types. Further, a range of different air change rates were considered, from 15 to 150 ACH. The room equipment layout and distribution was agreed upon by a panel of physicians and engineers as being representative of a typical newly designed operating room. The type of particle considered in this study was a squame, or skin scale, which is around 10 microns in size. Particles were released from three locations in the room, which represented likely sources of generation, and tracked to determine whether they would impinge on either the surgical site or a back table. The results were tabulated such that the lowest percentage of impacts would indicate the most appropriate ventilation system. The results show that ventilation systems that provide laminar flow conditions are the best choice, although some care needs too be taken in their design. A face velocity of around 30 to 35 fpm (0.15m/s to 0.18m/s) is sufficient from the laminar diffuser array, provided that the size of the diffuser array is appropriate.

131 citations

Journal ArticleDOI
TL;DR: In this paper, the frequency response of a normal shock in a diverging channel is calculated for application to problems of pressure oscillations in ramjet engines, and two limits of a linearized analysis arc are discussed: one represents isentropic flow on both sides of a shock wave; the other may be a crude estimate to the influence of flow separation induced by the wave.
Abstract: The frequency response of a normal shock in a diverging channel is calculated for application to problems of pressure oscillations in ramjet engines. Two limits of a linearized analysis arc discussed: one represents isentropic flow on both sides of a shock wave; the other may be a crude appr'l'I;imation to the influence of flow separation induced hy the wave. Numerical results arc given, and the influences of the shock wave on oscillations in the engine are discus,ed.

130 citations

Journal ArticleDOI
TL;DR: In this paper, the relationship between nozzle/diffuser flow coefficients and the performance of the valveless pumps with different Reynolds number ranges and conical angles is investigated. And the authors also proposed a flow model of the Valveless pump with a silicon micro-valveless wafer.
Abstract: The nozzle/diffuser flow with different Reynolds number ranges and conical angles is analyzed first. It is found that the flow coefficients of nozzle/diffuser ξn and ξd vary with angle with different trends for large (> 105) and small (<50) Reynolds number ranges. The flow model of valveless pumps with nozzle/diffusers is proposed, and the relationship between nozzle/diffuser flow coefficients and the performance of the valveless pumps is investigated. In experiments, silicon nozzle/diffuser elements with conical angles of 5°, 7.5° and 10° and a silicon micro valveless pump wafer are fabricated. The experimental ξd, ξn, and ξn/ξd decrease with increasing nozzle/diffuser angles in the Re range ( 2000) of the experiment. The pumping direction of the fabricated valveless pump agrees with the nozzle/diffuser flow experiments and analysis. The pump works successfully with the output flow rate of 28 μl/min under the input power of 50 mW and 500 Hz.

128 citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20224
2021156
2020186
2019216
2018236
2017263