scholarly journals Three-Dimensional Flow Predictions in Axial-Flow Turbine Cascades

1998 ◽  
Author(s):  
O. Niestroj ◽  
P. M. Came
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Axial Flow ◽  
Flow Angle ◽  
Contour Plots ◽  
Turbine Cascades ◽  
Flow Effects ◽  
Set Up ◽  
Annular Cascade ◽  
Good Agreement

Numerical investigations of the three-dimensional flowfields in a turbine linear cascade and in an annular, non-rotating turbine cascade have been carried out. Both cascades were the subjects of published experimental studies. In the experimental set-up for the annular cascade the hub wall upstream of the blades could be either stationary or rotating so that a collateral or a skewed inlet boundary layer could be achieved. The results of the computations have been compared with the experimental data. Total pressure loss coefficients and exit flow angles have been studied and in both cascades the predicted secondary flow effects are in good agreement with the experimental results. Two-dimensional contour plots in the measurement planes and pitchwise-averaged flow angle comparisons illustrate the accuracy of the computations.

Experimental Studies of Leading Edge Contouring Influence on Secondary Losses in Transonic Turbines

2012 ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Noticeable Effect ◽  
Flow Angle ◽  
Wide Range ◽  
Contour Plots

An experimental study of the hub leading edge contouring using fillets is performed in an annular sector cascade to observe the influence of secondary flows and aerodynamic losses. The investigated vane is a three dimensional gas turbine guide vane (geometrically similar) with a mid-span aspect ratio of 0.46. The measurements are carried out on the leading edge fillet and baseline cases using pneumatic probes. Significant precautions have been taken to increase the accuracy of the measurements. The investigations are performed for a wide range of operating exit Mach numbers from 0.5 to 0.9 at a design inlet flow angle of 90°. Data presented include the loading, fields of total pressures, exit flow angles, radial flow angles, as well as profile and secondary losses. The vane has a small profile loss of approximately 2.5% and secondary loss of about 1.1%. Contour plots of vorticity distributions and velocity vectors indicate there is a small influence of the vortex-structure in endwall regions when the leading edge fillet is used. Compared to the baseline case the loss for the filleted case is lower up to 13% of span and higher from 13% to 20% of the span for a reference condition with Mach no. of 0.9. For the filleted case, there is a small increase of turning up to 15% of the span and then a small decrease up to 35% of the span. Hence, there are no significant influences on the losses and turning for the filleted case. Results lead to the conclusion that one cannot expect a noticeable effect of leading edge contouring on the aerodynamic efficiency for the investigated 1st stage vane of a modern gas turbine.

scholarly journals An Investigation of Spanwise Mixing in Multistage Axial Flow Compressors

1992 ◽  
Author(s):  
S.-M. Li ◽  
M.-Z. Chen
Keyword(s):  
Secondary Flow ◽  
Turbulent Diffusion ◽  
Flow Model ◽  
Three Dimensional ◽  
Axial Flow ◽  
Equation System ◽  
Meridional Flow ◽  
Flow Effects ◽  
Annular Cascade ◽  
Axial Flow Compressors

An equation system has been deduced for meridional throughflow fields of multistage axial flow compressors, presenting different kinds of spanwise mixing effects of the fields in a unified form. The spanwise mixing in compressors is caused by three kinds of effects, molecular motion, turbulent diffusion, and circumferential non–uniformities, the last of which includes secondary flow effects and others. This equation system thus unifies the two models for spanwise mixing analyses by Adkins & Smith (1981) and Gallimore & Cumpsty (1986). The turbulent diffusion in the two–dimensional (2–D) meridional fields is determined by complex three–dimensional (3–D) shear flows in compressors, rather than the 2–D shearing alone, so a turbulence model for 2–D meridional flow calculations is proposed on the basis of a simplified 3–D shearing structure in compressors. The circumferentially non–uniform correlation terms in the equation system have been modeled on the basis of Adkins and Smith (1981) secondary flow model and the experimental data for annular cascade wakes. The results obtained agree well with the experiments for five compressors. The results also show some improvement over the previous theories.

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

A Method for the Calculation of the Tip Clearance Flow Effects in Axial Flow Compressors: Part II — Calculation Procedure

1993 ◽  
Author(s):  
I. K. Nikolos ◽  
D. I. Douvikas ◽  
K. D. Papailiou
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Vorticity Distribution ◽  
Clearance Flow ◽  
Calculation Results ◽  
Flow Effects ◽  
Set Up ◽  
Induced Velocity ◽  
Theoretical Procedure

An algorithm was set up for the implementation of the tip clearance models, described in Part I, in a secondary flow calculation method. A complete theoretical procedure was, thus, developed, which calculates the circumferentially averaged flow quantities and their radial variation due to the tip clearance effects. The calculation takes place in successive planes, where a Poisson equation is solved in order to provide the kinematic field. The self induced velocity is used for the positioning of the leakage vortex and a diffusion model is adopted for the vorticity distribution. The calculated pressure deficit due to the vortex presence is used, through an iterative procedure, in order to modify the pressure difference in the tip region. The method of implementation and the corresponding algorithm are described in this part of the paper and calculation results are compared to experimental ones for cascades and single rotors. The agreement between theory and experiment is good.

scholarly journals Numerical Investigation on Instability Flow Behaviors of Liquid Oxygen in a Feeding Pipeline with a Five-Way Spherical Cavity

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 926
Author(s):  
Fushou Xie ◽  
Siqi Xia ◽  
Erfeng Chen ◽  
Yanzhong Li ◽  
Hongwei Mao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spherical Cavity ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental System ◽  
Operating Conditions ◽  
Liquid Oxygen ◽  
Cavity Structure ◽  
Set Up ◽  
Pressure Fall

The hydrodynamic information of liquid oxygen in the conveying pipeline of cryogenic launch vehicles directly determines the reliability of the operation of the turbopump. A 0.09 MPa anomalous pressure fall phenomenon in the feeding system has been observed during the flight and run test of a cryogenic rocket with four parallel engines. In previous work, we set up a full-scale experimental system with liquid oxygen as media. The anomalous pressure fall was successfully reproduced. Experimental studies of this phenomenon suggest that the problem might be associated with vortices into the five-way spherical cavity structure. The objective of this study was to determine the three-dimensional instability flow by computational methods to identify and better understand the anomalous pressure fall phenomenon. A numerical model developed by the turbulent conservation equations was validated by experimental data. The generation and evolution of vortices into the five-way spherical cavity of feeding pipelines was captured. It was found that the root cause of the instability flow causing the unusual pressure fall is the formation of a spindle-like vortex into the five-way spherical cavity due to disturbance of the inlet liquid oxygen. The results showed that there is a mirror-symmetrical four-vortices structure in the absence of disturbance, in which the liquid oxygen pressure fall with the rise of the Reynolds number is in good agreement with the predicting values calculated by a set of traditional empirical correlations. In the case of the specific operating conditions, it is also consistent with the experimental results. When the disturbance occurs at the inlet of the spherical cavity, the mirror-symmetrical four-vortices structure gradually evolves into the mirror-symmetrical two-vortices structure. When the disturbance is further enhanced, the mirror-symmetrical two-vortices structure merge with each other to form a spindle-like vortex, which is similar to the Rankine vortex structure. The pressure fall on the corresponding side of the spindle-like vortex core reduces abnormally, and is about 0.07 MPa, which is consistent with the experimental data under certain disturbance conditions. Moreover, it was found that the spindle-like vortex is a stable eddy structure, and would continue to exist once it is formed, which could also not disappear with the removal of the disturbance.

The exploitation of three-dimensional flow in turbomachinery design

1998 ◽  
Vol 213 (2) ◽  
pp. 125-137 ◽  
Author(s):  
J. D. Denton ◽  
L Xu
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Field Calculation ◽  
3D Flow ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
3D Effects ◽  
Flow Effects ◽  
Turbomachinery Design

Many of the phenomena involved in turbomachinery flow can be understood and predicted on a two-dimensional (2D) or quasi-three-dimensional (Q3D) basis, but some aspects of the flow must be considered as fully three-dimensional (3D) and cannot be understood or predicted by the Q3D approach. Probably the best known of these fully 3D effects is secondary flow, which can only be predicted by a fully 3D calculation which includes the vorticity at inlet to the blade row. It has long been recognized that blade sweep and lean also produce fully 3D effects and approximate methods of calculating these have been developed. However, the advent of fully 3D flow field calculation methods has made predictions of these complex effects much more readily available and accurate so that they are now being exploited in design. This paper will attempt to describe and discuss fully 3D flow effects with particular reference to their use to improve turbomachine performance. Although the discussion is restricted to axial flow machines, many of the phenomena discussed are equally applicable to mixed and radial flow turbines and compressors.

scholarly journals Measurement and Prediction of Tip Leakage Losses in an Axial-Flow Transonic Turbine

1997 ◽  
Author(s):  
M. Wehner ◽  
J. Bütikofer ◽  
C-W. Hustad ◽  
A. Bölcs
Keyword(s):  
Flow Analysis ◽  
Axial Flow ◽  
Suction Side ◽  
Angle Of Incidence ◽  
Simple Method ◽  
Flow Angle ◽  
Tip Leakage ◽  
Gap Height ◽  
Exit Mach Number ◽  
Annular Cascade

This paper presents a simple method for predicting tip leakage losses in transonic axial-flow turbines. The method is based upon experimental work conducted on a flat plate at 5° incidence and with isentropic exit Mach number of 1.26. The tip gap height was varied from zero up to 15% of chord. Measurements were made (using Laser-2-Focus) of velocity vectors around the tip gap region. These revealed a strong shear layer emerging from the gap onto the suction side of the plate. The relative angle between the leakage flow and the freestream was identified as a key parameter determining the subsequent mixing and overall loss generation. The proposed model applies two-dimensional potential flow analysis to estimate the flow angle as a function of tip gap height and the angle of incidence. Subsequently, comparisons were made with experimental results obtained in an annular cascade on the outer profile of the last-stage blade of a steam turbine. The predicted tip leakage losses compare favourably with the measured values.

scholarly journals Analysis of Hydrodynamics of Fluid Flow on Corrugated Sheets of Packing

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Kumar Subramanian ◽  
Günter Wozny
Keyword(s):  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Elementary Geometry ◽  
Ansys Fluent ◽  
Vof Model ◽  
Corrugated Sheets ◽  
Wetted Area ◽  
Icem Cfd ◽  
Good Agreement

Modelling of the hydrodynamics behaviour of the liquid on the corrugated sheets of packing is studied using three-dimensional, volume-of-fluid (VOF) model that is incorporated in Ansys Fluent 12.0. The flow of three different liquids with different physical properties is modelled. A domain of corrugated sheets of packing resembling the real structured packing with little modifications in the elementary geometry is constructed using ICEM CFD 12.0. The quantitative comparisons of the wetting behavior from the simulations are in good agreement with experiments. Further, the study has been extended to understand the influence of the second corrugated sheet on the flow behavior. The contours from the simulations indicate the liquid hold-up in the crimp of two corrugated sheets, and these results are in good agreement with the earlier experimental studies performed using X-ray tomography in the literature. The result from the simulation shows that even for the high flow rate of around 811 mL/min for silicon-oil (DC5), only 60% of the corrugated sheet has been wetted. Hence, the efficiency of the existing packing can be further increased by increasing the wetted area in the corrugated sheet of packing.

Effect of Blade Curving on the Flow Field Structure in an Annular Turbine Cascade

1999 ◽  
Author(s):  
Yanping Song ◽  
Zhongqi Wang ◽  
Wencai Lu ◽  
Wenyuan Xu
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Field Structure ◽  
Turbine Cascade ◽  
Three Dimensional Flow ◽  
Surface Pressure Distribution ◽  
Pressure Distributions ◽  
Curved Blade ◽  
Turbine Cascades ◽  
Annular Cascade

In the present paper, two annular turbine cascades have been tested in order to investigate the effect of blade curving on the structure of the three-dimensional flow field. The blades in all two cascades have the same section and they are stacked on the trailing edge that is straight in the first and a circular arc in the second. Detailed cascade tests consisted of passage flow parameter traverses, blade and endwall surface pressure distribution, and flow visualization. The results show that the flow field is three dimensional in an annular cascade with different pressure distributions near two endwalls, whose direct effect is amplified through the creation of passage vortices of different scale and strength at hub and tip. Blade curving changes the pressure field completely, in axial, pitchwise and spanwise directions. The combined effect of 3-D characteristics and blade curving causes significant differences of flow field structure in curved blade.

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