Mathematical Formulation of Blade Surfaces in Turbomachinery: Part I — Theoretical Surface Formulations

This paper justifies recent trends in the mathematical definition of blade surfaces of impellers and rotors. The authors introduce a simple and efficient surface definition method, which is highly suited for numerical manufacture. Examples of a centrifugal compressor impeller, a mixed flow pump impeller and a gas turbine blade manufactured using the method are also presented. In this first part the theoretical approach and the mathematical derivations of the authors STRAIGHT-LINE-SURFACE structure method is introduced.

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Study of Internal Flows in a Mixed-Flow Pump Impeller at Various Tip Clearances Using 3D Viscous Flow Computations

Volume 1: Turbomachinery ◽

10.1115/90-gt-036 ◽

1990 ◽

Cited By ~ 6

Author(s):

Akira Goto

Keyword(s):

Reverse Flow ◽

Three Dimensional ◽

Interaction Mechanism ◽

Secondary Flows ◽

Wake Flow ◽

Navier Stokes ◽

Tip Leakage Flow ◽

Mixed Flow ◽

Pump Impeller ◽

Flow Pump

The complex three-dimensional flow fields in a mixed-flow pump impeller are investigated by applying the incompressible version of the Dawes’ 3D Navier-Stokes code. The applicability of the code is confirmed by comparison of computations with a variety of experimentally measured jet-wake flow patterns and overall performances at four different tip clearances including the shrouded case. Based on the computations, the interaction mechanism of secondary flows and the formation of jet-wake flow are discussed. In the case of large tip clearances, the reverse flow caused by tip leakage flow is considered to be the reason for the thickening of the casing boundary layer followed by the deterioration of the whole flow field.

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Anti-Cavitation Design of the Symmetric Leading-Edge Shape of Mixed-Flow Pump Impeller Blades

Symmetry ◽

10.3390/sym11010046 ◽

2019 ◽

Vol 11 (1) ◽

pp. 46 ◽

Cited By ~ 4

Author(s):

Di Zhu ◽

Ran Tao ◽

Ruofu Xiao

Keyword(s):

Fluid Dynamics ◽

Genetic Algorithm ◽

Design Method ◽

Leading Edge ◽

Mixed Flow ◽

Pump Impeller ◽

Cavitation Performance ◽

Optimal Sample ◽

Dynamics Method ◽

Flow Pump

Mixed-flow pumps compromise large flow rate and high head in fluid transferring. Long-axis mixed-flow pumps with radial–axial “spacing” guide vanes are usually installed deeply under water and suffer strong cavitation due to strong environmental pressure drops. In this case, a strategy combining the Diffusion-Angle Integral Design method, the Genetic Algorithm, and the Computational Fluid Dynamics method was used for optimizing the mixed-flow pump impeller. The Diffusion-Angle Integral Design method was used to parameterize the leading-edge geometry. The Genetic Algorithm was used to search for the optimal sample. The Computational Fluid Dynamics method was used for predicting the cavitation performance and head–efficiency performance of all the samples. The optimization designs quickly converged and got an optimal sample. This had an increased value for the minimum pressure coefficient, especially under off-design conditions. The sudden pressure drop around the leading-edge was weakened. The cavitation performance within the 0.5–1.2 Qd flow rate range, especially within the 0.62–0.78 Qd and 1.08–1.20 Qd ranges, was improved. The head and hydraulic efficiency was numerically checked without obvious change. This provided a good reference for optimizing the cavitation or other performances of bladed pumps.

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Performance Study of a Mixed Flow Impeller Covering an Unsteady Flow Field

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/pime_proc_1992_206_015_02 ◽

1992 ◽

Vol 206 (2) ◽

pp. 83-93 ◽

Cited By ~ 6

Author(s):

S Sarkar

Keyword(s):

Axial Flow ◽

Rotating Stall ◽

Operating Conditions ◽

Performance Study ◽

Mixed Flow ◽

Pump Impeller ◽

Wide Range ◽

Reversal Flow ◽

Flow Through ◽

Flow Pump

The results presented here are part of a detailed programme measuring the aerodynamics of a high specific speed mixed flow pump impeller over a wide range of operating conditions, including its behaviour in the unsteady stalled regime. The aim is to elucidate the physics of the flow through such an impeller. The noticeable features are the formation of part-span rotating stall cells having no periodicity and organized structure at reduced flow and also the shifting positions of reversal flow pockets as the flowrate changes. Measurements of loss and its variation with span-wise positions and flowrates enable the variation of local efficiency to be determined. The overall flow picture is similar to that expected in an axial flow impeller, though the present impeller displays a narrow stall hysteresis loop almost right through its operating range.

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3-D Viscous Flow Analysis of a Mixed Flow Pump Impeller

International Journal of Rotating Machinery ◽

10.1155/s1023621x01000057 ◽

2001 ◽

Vol 7 (1) ◽

pp. 53-63 ◽

Cited By ~ 2

Author(s):

Steven M. Miner

Keyword(s):

Static Pressure ◽

Stokes Equations ◽

Leading Edge ◽

Flow Coefficient ◽

Design Parameters ◽

Design Environment ◽

Suction Surface ◽

Mixed Flow ◽

Pump Impeller ◽

Flow Pump

This paper presents the results of a study using a coarse grid to analyze the flow in the impeller of a mixed flow pump. A commercial computational fluid dynamics code (FLOTRAN) is used to solve the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system. The standardk-εturbulence model is used. The mesh for this study uses 26,000 nodes and the model is run on a SPARCstation 20. This is in contrast to typical analyses using in excess of 100,000 nodes that are run on a super computer platform. The smaller mesh size has advantages in the design environment. Stage design parameters are, rotational speed 1185 rpm, flow coefficientφ=0.116, head coefficientψ=0.094, and specific speed 2.01 (5475 US). Results for the model include circumferentially averaged results at the leading and trailing edges of the impeller, and analysis of the flow field within the impeller passage. Circumferentially averaged results include axial and tangential velocities, static pressure, and total pressure. Within the impeller passage the static pressure and velocity results are presented on surfaces from the leading edge to the trailing edge, the hub to the shroud, and the pressure surface to the suction surface. Results of this study are consistent with the expected flow characteristics of mixed flow impellers, indicating that small CFD models can be used to evaluate impeller performance in the design environment.

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Closure to “Discussion of ‘An Experimental Study of Cavitation in a Mixed Flow Pump Impeller’” (1960, ASME J. Basic Eng., 82, p. 940)

Journal of Basic Engineering ◽

10.1115/1.3662808 ◽

1960 ◽

Vol 82 (4) ◽

pp. 940-940

Author(s):

G. M. Wood ◽

J. S. Murphy ◽

J. Farquhar

Keyword(s):

Experimental Study ◽

Mixed Flow ◽

Pump Impeller ◽

Flow Pump

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An Experimental Study of Cavitation in a Mixed Flow Pump Impeller

Journal of Basic Engineering ◽

10.1115/1.3662806 ◽

1960 ◽

Vol 82 (4) ◽

pp. 929-940 ◽

Cited By ~ 4

Author(s):

G. M. Wood ◽

J. S. Murphy ◽

J. Farquhar

Keyword(s):

Experimental Study ◽

Static Pressure ◽

Hydraulic Performance ◽

Mixed Flow ◽

Pump Impeller ◽

Flow Models ◽

Cavitation Performance ◽

Pressure Profiles ◽

Closed Water ◽

Flow Pump

A mixed flow impeller design was tested with six, five, and four vanes in a closed water loop to study the effects of cavitation on hydraulic performance and the results were compared with the work of other investigators. Two idealized flow models for incipient cavitation were derived to illustrate limits of cavitation design. It was found that both vane blockage and solidity effects are important when designing for optimum cavitation performance. Data showing incidence and speed effects plus the tip static pressure profiles in cavitating and noncavitating flow are also presented.

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