On the role of three-dimensional inverse design methods in turbomachinery shape optimization

1999 ◽  
Vol 213 (1) ◽  
pp. 27-42 ◽  
Author(s):  
M Zangeneh ◽  
A Goto ◽  
H Harada
Keyword(s):  
Flow Field ◽  
Inverse Method ◽  
Design Method ◽  
Three Dimensional ◽  
Design Guidelines ◽  
Secondary Flows ◽  
Inverse Design ◽  
Vaned Diffuser ◽  
Oil Flow ◽  
Inverse Design Method

The application of a three-dimensional (3D) inverse design method in which the blade geometry is computed for a specified distribution of circulation to the design of turbomachinery blades is explored by using two examples. In the first instance the method is applied to the design of radial and mixed flow impellers to suppress secondary flows. Based on our understanding of the fluid dynamics of the flow in the impeller, simple guidelines are developed for input specification of the inverse method in order to systematically design impellers with suppressed secondary flows and a more uniform exit flow field. In the second example the method is applied to the design of a vaned diffuser. Again based on the understanding of the detailed flow field in the diffuser obtained by using 3D viscous calculations and oil flow visualizations, simple design guidelines are developed for input specification to the inverse method in order to suppress corner separation. In both cases the guidelines are verified numerically and in the case of the diffuser further experimental validation is presented.

Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of Three-Dimensional Inverse Design Method: Part 1—Design and Numerical Validation

1996 ◽  
Vol 118 (3) ◽  
pp. 536-543 ◽  
Author(s):  
M. Zangeneh ◽  
A. Goto ◽  
T. Takemura
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Inverse Design ◽  
Suction Surface ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Inverse Design Method ◽  
Flow Pump

This paper describes the design of the blade geometry of a medium specific speed mixed flow pump impeller by using a three-dimensional inverse design method in which the blade circulation (or rVθ) is specified. The design objective is the reduction of impeller exit flow nonuniformity by reducing the secondary flows on the blade suction surface. The paper describes in detail the aerodynamic criteria used for the suppression of secondary flows with reference to the loading distribution and blade stacking condition used in the design. The flow through the designed impeller is computed by Dawes’ viscous code, which indicates that the secondary flows are well suppressed on the suction surface. Comparison between the predicted exit flow field of the inverse designed impeller and a corresponding conventional impeller indicates that the suppression of secondary flows has resulted in substantial improvement in the exit flow field. Experimental comparison of the flow fields inside and at exit from the conventional and the inverse designed impeller is made in Part 2 of the paper.

Optimization of Microturbine Aerodynamics Using CFD, Inverse Design and FEM Structural Analysis: 1st Report — Compressor Design

2004 ◽  
Author(s):  
Kosuke Ashihara ◽  
Akira Goto ◽  
Shijie Guo ◽  
Hidenobu Okamoto
Keyword(s):  
High Speed ◽  
Structural Reliability ◽  
Design Method ◽  
Three Dimensional ◽  
Design Procedure ◽  
Inverse Design ◽  
Blade Profile ◽  
Vaned Diffuser ◽  
Performance Improvements ◽  
Inverse Design Method

In this paper, a new aerodynamic design procedure is presented for a centrifugal compressor stage of a microturbine system. To optimize the three-dimensional (3-D) flows and the performance, an inverse design method, which numerically generates the 3-D blade geometry for specified blade loading distribution, has been applied together with the numerical validation using CFD (Computational Fluid Dynamics) and FEM (Finite Element Method). The blade profile along the shroud surface of the impeller was optimized based on the 3-D inverse design and CFD. However, the blade profile towards the hub surface was modified geometrically to achieve a nearly radial blade element especially at the inducer part of the impeller, in order to meet the required structural strength. The modified impeller successfully kept similar aerodynamic performance as that of a blade with a fully 3-D shape, whilst showing improved structural reliability. So, the proposed method to adopt the blade profile designed by the inverse method along the shroud, and to geometrically modify the blade profile towards the hub, was confirmed to be effective to design a high-speed compressor impeller. The vaned diffuser has also been re-designed using the inverse design method. The corner separation in the conventional wedge-type diffuser channel was suppressed in the new design. The stage performance improvements were confirmed by stage calculations using CFD.

On the Design Criteria for Suppression of Secondary Flows in Centrifugal and Mixed Flow Impellers

1998 ◽  
Vol 120 (4) ◽  
pp. 723-735 ◽  
Author(s):  
M. Zangeneh ◽  
A. Goto ◽  
H. Harada
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Centrifugal Compressor ◽  
Design Method ◽  
Three Dimensional ◽  
Design Guidelines ◽  
Secondary Flows ◽  
Mixed Flow ◽  
Optimum Pressure ◽  
Specific Speed

In this paper, for the first time, a set of guidelines is presented for the systematic design of mixed flow and centrifugal compressors and pumps with suppressed secondary flows and a uniform exit flow field. The paper describes the shape of the optimum pressure distribution for the suppression of secondary flows in the impeller with reference to classical secondary flow theory. The feasibility of achieving this pressure distribution is then demonstrated by deriving guidelines for the design specifications of a three-dimensional inverse design method, in which the blades are designed subject to a specified circulation distribution or 2πrVθ. The guidelines will define the optimum choice of the blade loading or ∂rVθ/∂m and the stacking condition for the blades. These guidelines are then used in the design of three different low specific speed centrifugal pump impellers and a high specific speed industrial centrifugal compressor impellers. The flows through all the designed impellers are computed numerically by a three-dimensional viscous code and the resulting flow field is compared to that obtained in the corresponding conventional impeller. The results show consistent suppression of secondary flows in all cases. The design guidelines are validated experimentally by comparing the performance of the inverse designed centrifugal compressor impeller with the corresponding conventional impeller. The overall performance of the stage with the inverse designed impeller with suppressed secondary flows was found to be 5 percent higher than the conventional impeller at the peak efficiency point. Exit flow traverse results at the impeller exit indicate a more uniform exit flow than that measured at the exit from the conventional impeller.

A Compressible Three-Dimensional Inverse Design Method Based on the Streamline Curvature Approach and Clebsch Formulation for Radial and Mixed Flow Turbomachines

2012 ◽  
Author(s):  
Xiao Pei Tian ◽  
Peng Shan
Keyword(s):  
Flow Field ◽  
Inverse Method ◽  
Design Method ◽  
Inverse Design ◽  
Periodic Flow ◽  
Mixed Flow ◽  
3 Dimensional ◽  
Streamline Curvature ◽  
Through Flow ◽  
Inverse Design Method

The through-flow inverse design method based on the streamline curvature approach is nowadays a widely used quasi-3-dimensional blades design method for radial and mixed flow turbomachines. The main limitation of this method is using the flow field on the mean stream surface S2,m to approximate the actual 3-dimensional flow field. Without an effective description of the periodic flow, it is impossible for this method to realize exactly the prescribed circumferentially averaged swirl rVθ. Is there any way to develop this classical through-flow inverse method to a 3-dimensional one conveniently? The answer is yes. A new compressible 3-dimensional inverse design method for radial and mixed flow turbomachines is presented in this paper. This new 3-dimensional inverse method provides a convenient and effective way to obtain the periodic flow field for the streamline curvature through-flow inverse method. Meanwhile, compared with another type of similar 3-dimensional inverse method firstly described by Tan etc. based on Stokes stream functions and Monge potential functions from the Clebsch formulation to calculate the circumferentially averaged flow and the periodic flow respectively, this new method has its own advantages. In order to assess the usefulness of the new method, four centrifugal impellers are designed under the same design specifications by four different inverse methods respectively. They are two quasi-3-dimensional streamline curvature through-flow inverse methods without and with a slip factor model, a 3-dimensional approximated inverse approach based on stream functions and Monge potential functions and the 3-dimensional inverse method presented here. The performances of the four impellers yielding from a RANS commercial solver are compared. The capabilities of the four methods to realize the target circumferentially averaged swirl are also studied.

scholarly journals Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of 3D Inverse Design Method: Part 1 — Design and Numerical Validation

1994 ◽  
Author(s):  
M. Zangeneh ◽  
A. Goto ◽  
T. Takemura
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Secondary Flows ◽  
Inverse Design ◽  
Experimental Comparison ◽  
Suction Surface ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Inverse Design Method ◽  
Flow Pump

This paper describes the design of the blade geometry of a medium specific speed mixed flow pump impeller by using a 3D inverse design method in which the blade circulation (or rVθ) is specified. The design objective being the reduction of impeller exit flow non-uniformity by reducing the secondary flows on the blade suction surface. The paper describes in detail the aerodynamic critria used for the suppression of secondary flows with reference to the loading distribution and blade stacking condition used in the design. The flow through the designed impeller is computed by Dawes viscous code, which indicates that the secondary flows are well suppressed on the suction surface. Comparison between the predicted exit flow field of the inverse designed impeller and a corresponding conventional impeller indicates that the suppression of secondary flows has resulted in substantial improvement in the exit flow field. Experimental comparison of the flow fields inside and at exit from the conventional and the inverse designed impeller is made in part 2 of the paper.

Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of Three-Dimensional Inverse Design Method: Part 2—Experimental Validation

1996 ◽  
Vol 118 (3) ◽  
pp. 544-551 ◽  
Author(s):  
A. Goto ◽  
T. Takemura ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Three Dimensional ◽  
Flow Fields ◽  
Secondary Flows ◽  
Inverse Design ◽  
Suction Surface ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Inverse Design Method ◽  
Flow Pump

In Part 1 of this paper, a mixed-flow pump impeller was designed by a fully three-dimensional inverse design method, aimed at suppressing the secondary flows on the blade suction surface. In this part, the internal flow fields of the impeller are investigated experimentally, using flow visualization and phase-locked measurements of the impeller exit flow, in order to validate the effects of secondary flow suppression. The flow fields are compared with those of a conventional impeller, and it is confirmed that the secondary flows on the blade suction surface are well suppressed and the uniformity of the exit flow fields is improved substantially, in both circumferential and spanwise directions. The effects of tip clearance and the number of blades for the inverse designed impeller are also investigated experimentally and numerically.

Suppression of Secondary Flows in a Turbine Nozzle With Controlled Stacking Shape and Exit Circulation by 3D Inverse Design Method

1999 ◽  
Author(s):  
H. Watanabe ◽  
H. Harada
Keyword(s):  
Nozzle Exit ◽  
Inverse Method ◽  
Design Method ◽  
Secondary Flows ◽  
Inverse Design ◽  
Turbine Stage ◽  
Axial Turbine ◽  
Work Distribution ◽  
Inverse Design Method ◽  
3D Stacking

For the axial turbine stage, the design of circulation rVθ¯ distribution between the nozzle and blade has an important effect on the stage performance, because it determines the work distribution in the blade, the stage reaction and the twisting shape of the blade. This paper describes the new method of full 3D design for axial turbine nozzles and blades by applying the 3D inverse design method in which the blade geometry can be determined by specified distributions of circulation rVθ¯ and blade thickness. In this 3D inverse design method, spanwise work distribution of the turbine stage is controlled by specifying the rVθ¯ distribution of the nozzle exit. In this design procedure, rVθ¯ distribution at the nozzle exit and 3D stacking condition are both controlled by 3D inverse method so as to suppress the nozzle secondary flows effectively. The desirable rVθ¯ distribution and 3D stacking shape which were obtained by the 3D inverse method were confirmed by Dawes’ 3D Navier-Stokes analysis. The results shows that the secondary loss is reduced when the design rVθ¯ at the mid-span is set larger compared to that near the endwall. In addition to the control of the rVθ¯ distribution, 3D stacking shape added only in the front part of the nozzle is very effective to suppress the secondary flows, although this 3D stacking shape is very simple compared to a conventional bowed type stacking. Moreover, when this stacking shape is used, spanwise distribution of work does not change from the design condition unlike the case of conventional bowed type stacking shape. The results of single stage performance test conducted using an air turbine facility show an improvement in efficiency compared to the 2D designed stage and prove viability of the 30 inverse design of axial turbine blades.

Reformulation of a Three-Dimensional Inverse Design Method for Application in a High-Fidelity CFD Environment

2012 ◽  
Author(s):  
Michel van Rooij ◽  
Adam Medd
Keyword(s):  
Inverse Method ◽  
Design Method ◽  
Three Dimensional ◽  
Inverse Design ◽  
Design Quality ◽  
Specific Flow ◽  
Flow Solver ◽  
The Difference ◽  
Inverse Design Method ◽  
Stage Matching

Three-dimensional inverse design has been shown to be a reliable and powerful tool for facilitating the refinement of blading design and improving stage matching, thereby providing increased aero-design quality and productivity in difficult design situations. However, inverse design has not been incorporated widely into design systems. Reasons for this may be that many inverse techniques are limited to two dimensional problems, or are highly integrated with a specific flow solver and therefore difficult to integrate with proprietary or commercial CFD methods. A reformulation of a three-dimensional inverse design method is presented here that overcomes these limitations. The new method is fully consistent with viscous flow modeling. Camber modification is performed using a blade velocity derived from the difference between prescribed and actual pressure loading. The new inverse method completely eliminates differences between analysis and inverse calculations. Moreover, the reformulation effectively decouples the inverse method from the flow solver. This makes it possible to supplement any CFD-code with the developed inverse design module, provided an interface can be created between the solver and the inverse module through which to pass information on flow and mesh. This makes inverse design available to most design offices.

scholarly journals Incidence Angle and Pitch-Chord Effects on Secondary Flows Downstream of a Turbine Cascade

1992 ◽  
Author(s):  
A. Perdichizzi ◽  
V. Dossena
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Turbine Cascade ◽  
Oil Flow ◽  
Secondary Velocity ◽  
Secondary Flow Field

This paper describes the results of an experimental investigation of the three-dimensional flow downstream of a linear turbine cascade at off-design conditions. The tests have been carried out for five incidence angles from −60 to +35 degrees, and for three pitch-chord ratios: s/c = 0.58,0.73,0.87. Data include blade pressure distributions, oil flow visualizations, and pressure probe measurements. The secondary flow field has been obtained by traversing a miniature five hole probe in a plane located at 50% of an axial chord downstream of the trailing edge. The distributions of local energy loss coefficients, together with vorticity and secondary velocity plots show in detail how much the secondary flow field is modified both by incidence and cascade solidity variations. The level of secondary vorticity and the intensity of the crossflow at the endwall have been found to be strictly related to the blade loading occurring in the blade entrance region. Heavy changes occur in the spanwise distributions of the pitch averaged loss and of the deviation angle, when incidence or pitch-chord ratio is varied.

Hydrodynamic Design System for Pumps Based on 3-D CAD, CFD, and Inverse Design Method

2002 ◽  
Vol 124 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Akira Goto ◽  
Motohiko Nohmi ◽  
Takaki Sakurai ◽  
Yoshiyasu Sogawa
Keyword(s):  
Computer Aided Design ◽  
High Performance ◽  
Design Method ◽  
High Reliability ◽  
Secondary Flows ◽  
System Structure ◽  
Inverse Design ◽  
Design System ◽  
Centrifugal Impeller ◽  
Inverse Design Method

A computer-aided design system has been developed for hydraulic parts of pumps including impellers, bowl diffusers, volutes, and vaned return channels. The key technologies include three-dimensional (3-D) CAD modeling, automatic grid generation, CFD analysis, and a 3-D inverse design method. The design system is directly connected to a rapid prototyping production system and a flexible manufacturing system composed of a group of DNC machines. The use of this novel design system leads to a drastic reduction of the development time of pumps having high performance, high reliability, and innovative design concepts. The system structure and the design process of “Blade Design System” and “Channel Design System” are presented. Then the design examples are presented briefly based on the previous publications, which included a centrifugal impeller with suppressed secondary flows, a bowl diffuser with suppressed corner separation, a vaned return channel of a multistage pump, and a volute casing. The results of experimental validation, including flow fields measurements, were also presented and discussed briefly.

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