Diffuser (thermodynamics)

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

Optimization of Vane Diffuser in a Mixed-Flow Pump for High Efficiency Design

Abstract: This paper presents an optimization procedure for high-efficiency design of a mixed-flow pump. Optimization techniques based on a weighted-average surrogate model are used to optimize a vane diffuser of a mixed-flow pump. Validation of the numerical results is performed through experimental data for head, power and efficiency. Three-level full factorial design is used to generate nine design points within the design space. Three-dimensional Reynoldsaveraged Navier-Stokes equations with the shear stress transport turbulence model are discretized by using finite volume approximation and solved on hexahedral grids to evaluate the efficiency as the objective function. In order to reduce pressure loss in the vane diffuser, two variables defining the straight vane length ratio and the diffusion area ratio are selected as design variables in the present optimization. As the results of the design optimization, the efficiency at the design flow coefficient is improved by 7.05% and the off-design efficiencies are also improved in comparison with the reference design.

Air cycle machine and fan inlet/diffuser therefor

Abstract: A fan inlet and diffuser apparatus (30) is provided with a lobed mixer (60) for intermixing fan bypass air (25) with a flow of fan discharge air (27). The fan inlet and diffuser apparatus (30) is particularly adapted for use in a inducing a flow of cooling air (21) through an upstream heat exchanger (20) and thence directing a portion (23) of the cooling air passing from the heat exchanger to the inlet side of the fan (14) of an air cycle machine (10), while directing the remaining portion (25) to bypass the fan (14) and pass into the central outlet flow passage (52) flowing over the mixing ejector (60) which imparts a directional swirl to the bypass flow (25) and a counter swirl to the fan discharge flow (27) passing from the fan outlet through the interior of the mixer (60), thereby enhancing the mixing of these two flows within the passage (52).

Experimental Investigation of Rotor-Stator Interaction in a Centrifugal Pump With Several Vaned Diffusers

Abstract: This paper describes an experimental investigation of rotor-stator interaction in a centrifugal pump with several vaned diffusers. Steady and unsteady diffuser vane pressure measurements were made for a two-dimensional test impeller. Unsteady impeller blade pressure measurements were made for a second two-dimensional impeller with blade number and blade geometry identical to the two-dimensional impeller used for the diffuser vane pressure measurements. The experiments were conducted for different flow coefficients and differeent radial gaps between the impeller blade trailing edge and the diffuser vane leading edge (5 and 8 percent of the impeller discharge radius). The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. The largest pressure fluctuations on the diffuser vanes were observed to occur on the suction side of the vane near the vane leading edge, whereas on the impeller blades the largest fluctuations were observed to occur at the blade trailing edge. However, the dependence of the fluctuations on the flow coefficient was found to be different for te diffuser vanes and the impeller blades; on the vane suction side, the fluctuations were largest for the maximum flow coefficient and decreased with decreasing flow coefficient, whereas at the blade trailing edge, the fluctuations were smallest for the maximum flow coefficient and increased with decreasing flow coefficient. Increasing the number of the diffuser vanes resulted in a significant decrease of the impeller blade pressure fluctuations. The resulting lift on the diffuser vanes was computed from the vane pressure measurements; the magnitude of the fluctuating lift was found to be larger than the steady lift.

Pressurized bearing system for submersible motor

Abstract: Pressurized lubricant is used for stabilizing shaft bearings in an electrical submersible pump motor. A lubricant pump is located within the motor housing. The lubricant pump has a set of impellers attached to a lower end of the shaft and rotating with the shaft, the impellers being located in the flow path of the lubricant. A diffuser is located upstream of and adjacent each impeller. The impellers increase the radial velocity of the lubricant, and this velocity is converted into a pressure head at the impeller outlet. The lubricant flows through the first diffuser, through the first impeller, through the second diffuser, and then flows through the second impeller and out into a reservoir. The shaft has an axial flow passage with an outlet at each bearing. The outlet has at least three ports arranged symmetrically around the shaft for discharging lubricant into a clearance between the shaft and bearing to create a fluid film.

Radial split diffuser

Abstract: The invention relates to a radial split diffuser (3) with an inner casing (13) and an outer casing (14) joined together along a cylindrical joint (15). Each diffuser passage is intersected by and extends transversely across the joint. The advantages of this design include: the elimination of a transition within the initial portion of the passages where air flow speeds are supersonic and minute surface discontinuities can significantly effect performance; and the simplification of manufacturing through use of metal castings to replace sheet metal fabrications in the manufacture of diffusers. The joint (15) in the present invention can be located downstream from the diffuser inlet a sufficient distance in a lower velocity area. The joint is located to enable access for precise machining of the critical initial portion of the passages within the inner casing, and to minimise air flow disturbance in the initial portion.