Blade Loading and Numerical Slip Factor of Centrifugal Compressor Impellers

1999 ◽  
Author(s):  
JongSik Oh
Keyword(s):  
State Of The Art ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Blade Design ◽  
Direct Relation ◽  
Blade Profile ◽  
Blade Loading ◽  
Slip Factor ◽  
Compressible Turbulent Flow ◽  
Good Agreement

Abstract Through the state-of-the-art CFD approach, the Eckardt radial bladed and backswept impellers were analyzed to investigate the effect of blade loadings from blade design shape on the slip factor variation for the change of the flow rate. In addition, a new design of the blade profile was arbitrarily attempted to generate a center-loading pattern in the Eckardt backswept impeller. Three dimensional compressible turbulent flow analysis was applied, with the Baldwin-Lomax turbulence model adopted, to get the numerical slip factor, using the mass-averaged concept, at the discharge plane of each impeller. The numerical slip factors are in good agreement with the experimental ones, and the Wiesner’s slip factors are found to deviate further from the numerical and experimental ones, especially in the two backswept impellers. The deviation angles and the blade loadings in the meridional channel are found in no direct relation with the trend of change of the slip factors. Blade-to-blade loadings in midspan location are, however, found in direct relation, especially at the sections where maximum loadings are to be expected. That information can be utilized in establishing an improved expression for slip factor in the future.

Influence of Blade Aerodynamic Loading on Efficiency of Radial-Inflow Turbines

1992 ◽  
Author(s):  
T. Takamura ◽  
F. Nishiguchi
Keyword(s):  
Shape Factor ◽  
Rotor Blade ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Blade Loading ◽  
Stream Surface ◽  
Turbine Efficiency ◽  
Blade Shape ◽  
Velocity Triangle ◽  
The Mean

This paper describes the relation between turbine efficiency and rotor blade loading parameters. Tests were carried out on 12 kinds of rotors, which had the same inlet velocity triangle and meridional contour, but different blade numbers (8–11) and blade lengths. The momentum thickness and shape factor of the boundary layers obtained from the results of a quasi-three dimensional flow analysis were used as the rotor blade loading parameters. It was found that blade loading could be evaluated by the shape factor at the mean stream surface and that turbine efficiency was affected by the blade shape of the exducer.

Improving a conjugate-heat-transfer immersed-boundary method

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1272-1288 ◽  
Author(s):  
Dario De Marinis ◽  
Marco Donato de Tullio ◽  
Michele Napolitano ◽  
Giuseppe Pascazio
Keyword(s):  
Turbulent Flow ◽  
Immersed Boundary Method ◽  
Conjugate Heat Transfer ◽  
State Of The Art ◽  
Three Dimensional ◽  
Immersed Boundary ◽  
Turbine Cascade ◽  
Wall Functions ◽  
Content Type ◽  
Compressible Turbulent Flow

Purpose – The purpose of this paper is to provide the current state of the art in the development of a computer code combining an immersed boundary method with a conjugate heat transfer (CHT) approach, including some new findings. In particular, various treatments of the fluid-solid-interface conditions are compared in order to determine the most accurate one. Most importantly, the method is capable of computing a challenging three dimensional compressible turbulent flow past an air cooled turbine vane. Design/methodology/approach – The unsteady Reynolds-averaged Navier–Stokes (URANS) equations are solved within the fluid domain, whereas the heat conduction equation is solved within the solid one, using the same spatial discretization and time-marching scheme. At the interface boundary, the temperatures and heat fluxes within the fluid and the solid are set to be equal using three different approximations. Findings – This work provides an accurate and efficient code for solving three dimensional CHT problems, such as the flow through an air cooled gas turbine cascade, using a coupled immersed boundary (IB) CHT methodology. A one-to-one comparison of three different interface-condition approximations has shown that the two multidimensional ones are slightly superior to the early treatment based on a single direction and that the one based on a least square reconstruction of the solution near the IB minimizes the oscillations caused by the Cartesian grid. This last reconstruction is then used to compute a compressible turbulent flow of industrial interest, namely, that through an air cooled gas turbine cascade. Another interesting finding is that the very promising approach based on wall functions does not combine favourably with the interface conditions for the temperature and the heat flux. Therefore, current and future work aims at developing and testing appropriate temperature wall functions, in order to further improve the accuracy – for a given grid – or the efficiency – for a given accuracy – of the proposed methodology. Originality/value – An accurate and efficient IB CHT method, using a state of the art URANS parallel solver, has been developed and tested. In particular, a detailed study has elucidated the influence of different interface treatments of the fluid-solid boundary upon the accuracy of the computations. Last but not least, the method has been applied with success to solve the well-known CHT problem of compressible turbulent flow past the C3X turbine guide vane.

A Parametric Study of Radial Turbomachinery Blade Design in Three-Dimensional Subsonic Flow

1990 ◽  
Vol 112 (3) ◽  
pp. 338-345 ◽  
Author(s):  
W. S. Ghaly
Keyword(s):  
Parametric Study ◽  
Subsonic Flow ◽  
Pressure Field ◽  
Design Method ◽  
Three Dimensional ◽  
Rate Of Change ◽  
Blade Design ◽  
Blade Loading ◽  
Pressure Fields ◽  
Blade Shape

An aerodynamic design method is described and used to implement a parametric study of radial turbomachinery blade design in three-dimensional subsonic flow. Given the impeller hub and shroud, the number of blades and their stacking position, the design method gives the detailed blade shape, flow, and pressure fields that would produce a prescribed tangentially averaged swirl schedule. The results from that study show that decreasing the number of blades increases the blade wrap, and that the blade loading is strongly affected by the rate of change of mean swirl along the mean streamlines. The results also show that the blade shape and the pressure field are rather sensitive to the prescribed mean swirl schedule, which suggests that, by carefully tailoring the swirl schedule, one might be able to control the blade shape and the pressure field and hence secondary flow.

Three-Dimensional Flow Analysis and Improvement of Slip Factor Model for Forward-Curved Blades Centrifugal Fan

2003 ◽  
Author(s):  
En-Min Guo ◽  
Kwang-Yong Kim
Keyword(s):  
Factor Model ◽  
Pressure Coefficient ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Correction Method ◽  
Factor Models ◽  
Centrifugal Impeller ◽  
Centrifugal Fan ◽  
Slip Factor ◽  
Cfd Analyses

The objective of this work is to develop improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan by investigating the validity of various slip factor models. Both steady and unsteady three-dimensional CFD analyses were performed with a commercial code to validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the presented model takes into account the effect of blade curvature. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peak total pressure coefficient.

Optimum Aerodynamic Design of Centrifugal Compressor Impeller Using an Inverse Method Based on Meridional Viscous Flow Analysis

2017 ◽  
Author(s):  
Nobuhito Oka ◽  
Masato Furukawa ◽  
Kazutoyo Yamada ◽  
Sasuga Itou ◽  
Seiichi Ibaraki ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Optimum Design ◽  
Inverse Method ◽  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Blade Design ◽  
Aerodynamic Design ◽  
Compressor Impeller ◽  
Optimum Aerodynamic

An optimum aerodynamic design method for centrifugal compressor impeller has been developed. The present optimum design method is using a genetic algorithm (GA) and a two-dimensional inverse blade design method based on a meridional viscous flow analysis. In the meridional viscous flow analysis, an axisymmetric viscous flow is numerically analyzed on a two-dimensional meridional grid to determine the flow distribution around the impeller. Full and splitter blade effects to the flow field are successfully evaluated in the meridional viscous flow analysis by a blade force modeling. In the inverse blade design procedure, blade loading distribution is given as the design variable. In the optimization procedure, the total pressure rise and adiabatic efficiency obtained from the meridional viscous flow analysis are employed as objective functions. Aerodynamic performance and three-dimensional flow fields in the Pareto-optimum design and conventional design cases have been investigated by three-dimensional Reynolds averaged Navier-Stokes (3D-RANS) and experimental analyses. The analyses results show performance improvements and suppressions of flow separations on the suction surfaces in the optimum design cases. Therefore, the present aerodynamic optimization using the inverse method based on the meridional viscous flow analysis is successfully achieved.

A Parametric Study of Radial Turbomachinery Blade Design in Three-Dimensional Subsonic Flow

1989 ◽  
Author(s):  
W. S. Ghaly ◽  
C. S. Tan
Keyword(s):  
Parametric Study ◽  
Subsonic Flow ◽  
Pressure Field ◽  
Design Method ◽  
Three Dimensional ◽  
Rate Of Change ◽  
Blade Design ◽  
Blade Loading ◽  
Pressure Fields ◽  
Blade Shape

An aerodynamic design method is described and used to implement a parametric study of radial turbomachinery blade design in three-dimensional subsonic flow. Given the impeller hub and shroud, the number of blades and their stacking position, the design method gives the detailed blade shape, flow and pressure fields that would produce a prescribed tangential averaged swirl schedule. The results from that study show that decreasing the number of blades increases the blade wrap, and that the blade loading is strongly affected by the rate of change of mean swirl along the mean streamlines. The results also show that the blade shape and the pressure field are rather sensitive to the prescribed mean swirl schedule which suggests that, by carefuly tailoring the swirl schedule, one might be able to control the blade shape and the pressure field and hence secondary flow.

scholarly journals A Fully Three-Dimensional Inverse Method for Turbomachinery Blading in Transonic Flows

1992 ◽  
Author(s):  
T. Q. Dang
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Transonic Flow ◽  
Inverse Method ◽  
Three Dimensional ◽  
Blade Design ◽  
Blade Profile ◽  
Transonic Flows ◽  
Blade Passage ◽  
Highly Loaded

This paper presents a procedure to extend a recently developed fully three-dimensional inverse method for highly-loaded turbomachine blades into the transonic-flow regime. In this inverse method, the required three-dimensional blade profile to produce a prescribed swirl schedule is determined iteratively using the blade boundary conditions. In the present implementation, the flow is assumed to be inviscid and the blades are assumed to be infinitely thin. The relevant equations are solved in the conservative forms and are discretized in all three directions using a finite-volume technique. Calculations are carried out for the design of high-pressure axial- and centrifugal-compressor rotors. These examples include prescribed swirl schedules that correspond to blade design that are shock-free and blade design that have rapid compression regions in the blade passage.

Numerical Investigation of Blade Profile Effects on Aerodynamic Performance of Ultra-Highly Loaded Turbine Cascades

2004 ◽  
Author(s):  
Hoshio Tsujita ◽  
Shimpei Mizuki ◽  
Atsumasa Yamamoto
Keyword(s):  
Three Dimensional ◽  
Simple Algorithm ◽  
Aerodynamic Performance ◽  
Secondary Flows ◽  
Turbine Cascade ◽  
Blade Profile ◽  
Suction Surface ◽  
Blade Loading ◽  
Turbine Cascades ◽  
Highly Loaded

The increase of blade loading of a turbine cascade makes it possible to reduce the number of blades and stages, and consequently to decrease both the weights and the costs for manufacturing and maintenance. However, strong secondary flows appear in such highly loaded turbine cascades due to the high turning angles which reduce the efficiency. In the present study, the effects of blade profile on the aerodynamic performance of a stationary linear ultra-highly loaded turbine cascade (UHLTC), which will be used for the future gas turbine engines of hypersonic transport, were investigated numerically. The two and three dimensional calculations were carried out for the flows within the three types of UHLTC, which have the same design turning angle of 160 degree and with the different profile of the suction surface. The first was named ‘Original’. The others were ‘Up’ and ‘Down’ which had the longer length of suction surface and the shorter one than that of the Original, respectively. In the present computational code, the governing equations for the incompressible turbulent flow which include the standard k-ε turbulence model were solved by the SIMPLE algorithm. The convection term was estimated by the third order upwind difference scheme. The present computed results were examined by comparing with the experimental results. The total pressure loss, the profile loss, the secondary loss and the blade loading distribution for the three types of UHLTC were compared in detail with each other to reveal the effect of blade profile on the aerodynamic performance of UHLTC.

Analysis of 8 Centrifugal Compressor Impellers Using Two Different CFD Methods: Part II — Blockage and Slip Characteristics

2001 ◽  
Author(s):  
JongSik Oh
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Simple Form ◽  
Model Equation ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Blade Loading ◽  
Design Processes ◽  
Slip Factor ◽  
Improved Model

As the second part of the author’s study, the aerodynamic exit blockage and the slip factor of 8 centrifugal compressor impellers are investigated, when the flow rate is changed from numerical stall to choke, using three-dimensional Navier-Stokes analysis results. Based on all the exit blockage distributions, an improved model equation with two adjusting coefficients is developed for the use in design processes with the agile engineering purpose. A popular expression of simple slip factors, the Wiesner’s equation, cannot be applied in design processes when more accurate prediction is strongly required at design and off-design points. Slip factor variation is found to be also influenced by the blade loadings at midspan. When the flow rate is changed, a pattern of the slip factor variations is assumed to be a simple form which can be explained using midspan blade loading distributions.

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