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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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TL;DR: In this paper, an efficient and robust algorithm is presented for the optimum design of plane symmetric diffusers handling incompressible turbulent flow, which uses the CFD software: Fluent for the hydrodynamic analysis and employs a GA for optimization.
Abstract: An efficient and robust algorithm is presented for the optimum design of plane symmetric diffusers handling incompressible turbulent flow. The indigenously developed algorithm uses the CFD software: Fluent for the hydrodynamic analysis and employs a genetic algorithm (GA) for optimization. For a prescribed inlet velocity and outlet pressure, pressure recovery coefficient C (the objective function) is estimated computationally for various design options. The CFD software and the GA have been combined in a monolithic platform for a fully automated operation using some special control commands. Based on the developed algorithm, an extensive exercise has been made to optimize the diffuser shape. Different methodologies have been adopted to create a large number of design options. Interestingly, not much difference has been noted in the optimum C values obtained through different approaches. However, in all the approaches, a better design has been obtained through a proper selection of the number of design variables. Finally, the effect of diffuser length on the optimum shape has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.
23 citations
TL;DR: In this paper, the authors focus on the improvement of the internal volute performance by taking into account the interaction between the diffuser and the volute, and two alternative configurations with enhanced aerodynamic performance are presented.
Abstract: Internal volutes have a constant outer radius, slightly larger than the diffuser exit radius, and the circumferential increase of the cross section is accommodated by a decrease of the inner radius. They allow the design of compact radial compressors and hence are very attractive for turbochargers and high-pressure pipeline compressors where small housing diameters have a favorable impact on weight and cost. Internal volutes, however, have higher losses and lower pressure rise than external ones in which the center of the cross sections is located at a larger radius than the diffuser exit. This paper focuses on the improvement of the internal volute performance by taking into account the interaction between the diffuser and the volute. Two alternative configurations with enhanced aerodynamic performance are presented. A first one features a novel, non-axi-symmetric diffuser/internal volute combination. It demonstrates an increased pressure ratio and lower loss over most of the operating range at all rotational speeds. The circumferential pressure distortion at off design operation is slightly larger than in the original configuration with a concentric vaneless diffuser. Alternatively, a parallel-walled Low-Solidity Diffuser (LSD) with an internal volute allows a reduction of the unsteady load on the impeller and an improved performance close to the one of a vaneless concentric diffuser with a large external volute.Copyright © 2005 by ASME
23 citations
TL;DR: In this article, a seven-hole probe was used to measure the mixing effectiveness of a lobe-ejector combined with a double-wall diffuser, and the results showed that the lobe ejected the air from surrounding between the double walls as well as the secondary flow.
23 citations
Patent•
19 Oct 1995
TL;DR: In this paper, a weld shield is used to provide an atmosphere of inert gas within a conduit in an underbead region where an external weld joint is to be produced, and a seal is positioned immediately upstream from the diffuser structure and is positioned to engage the inner walls of the conduit so as to prevent the passage of gas in an upstream direction.
Abstract: A weld shield apparatus provides an atmosphere of inert gas within a conduit in an underbead region where an external weld joint is to be produced. The weld shield apparatus includes a diffuser structure having a convex exterior surface that is defined by a wall structure, the convex exterior surface is shaped to fit within the conduit and to be separated from an inner wall of the conduit by a clearance space. The diffuser wall structure is comprised of a porous material which enables gas communication between an inlet to the diffuser and the convex exterior surface. A seal is positioned immediately upstream from the diffuser structure and is positioned to engage the inner walls of the conduit so as to prevent the passage of gas in an upstream direction. A source of gas is coupled to the inlet to the diffuser structure and enables inert gas to pass through the porous material and to flow in a laminar manner, via the clearance space, past the underbead region and into the downstream region of the conduit. The resulting laminar flow and use of a neutral density gas enable small amounts of gas to be employed as a weld shield.
23 citations
TL;DR: In this article, the vaneless diffuser of a 1-3-dia low-speed backwept centrifugal compressor using a phase lock loop technique was used for hot-wire anemometer measurements.
Abstract: Hot-wire anemometer measurements have been made in the vaneless diffuser of a 1-3-dia low-speed backswept centrifugal compressor using a phase lock loop technique. Radial, tangential, and axial velocity measurements have been made on eight measurement planes through the diffuser. The flow field at the diffuser entry clearly shows the impeller jet-wake flow pattern and the blade wakes. The passage wake is located on the shroud side of the diffuser and mixes out slowly as the flow moves through the diffuser. The blade wakes, on the other hand, distort and mix out rapidly in the diffuser. Contours of turbulent kinetic energy are also presented on each of the measurement stations, from which the regions of turbulent mixing can be deduced
23 citations