Flow Development Through Interturbine Diffusers

1998 ◽  
Vol 120 (2) ◽  
pp. 298-304 ◽  
Author(s):  
R. G. Dominy ◽  
D. A. Kirkham ◽  
A. D. Smith
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Experimental Measurements ◽  
Good Prediction ◽  
Pressure Gradients ◽  
Computational Simulations ◽  
Flow Development ◽  
Inlet Swirl

Interturbine diffusers offer the potential advantage of reducing the flow coefficient in the following stages, leading to increased efficiency. The flows associated with these ducts differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. Experimental data and numerical simulations clearly reveal the generation of significant secondary flows as the flow develops through the diffuser in the presence of cross-passage pressure gradients. The further influence of inlet swirl is also demonstrated. Data from experimental measurements with and without an upstream turbine are discussed and computational simulations are shown not only to give a good prediction of the flow development within the diffuser but also to demonstrate the importance of modeling the fully three-dimensional nature of the flow.

scholarly journals Flow Development Through Inter-Turbine Diffusers

1996 ◽  
Author(s):  
Robert G. Dominy ◽  
David A. Kirkham ◽  
Andrew D. Smith
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Experimental Measurements ◽  
Good Prediction ◽  
Pressure Gradients ◽  
Computational Simulations ◽  
Flow Development ◽  
Inlet Swirl

Inter-turbine diffusers offer the potential advantage of reducing the flow coefficient in the following stages leading to increased efficiency. The flows associated with these ducts differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. Experimental data and numerical simulations clearly reveal the generation of significant secondary flows as the flow develops through the diffuser in the presence of cross-passage pressure gradients. The further influence of inlet swirl is also demonstrated. Data from experimental measurements with and without an upstream turbine are discussed and computational simulations are shown not only to give a good prediction of the flow development within the diffuser but also to demonstrate the importance of modelling the fully three-dimensional nature of the flow.

Visualization Study of Flow in Axial Flow Inducer

1972 ◽  
Vol 94 (4) ◽  
pp. 777-787 ◽  
Author(s):  
B. Lakshminarayana
Keyword(s):  
Radial Velocity ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Axial Flow ◽  
Flow Theory ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Flow Through

A visualization study of the flow through a three ft dia model of a four bladed inducer, which is operated in air at a flow coefficient of 0.065, is reported in this paper. The flow near the blade surfaces, inside the rotating passages, downstream and upstream of the inducer is visualized by means of smoke, tufts, ammonia filament, and lampblack techniques. Flow is found to be highly three dimensional, with appreciable radial velocity throughout the entire passage. The secondary flows observed near the hub and annulus walls agree with qualitative predictions obtained from the inviscid secondary flow theory. Based on these investigations, methods of modeling the flow are discussed.

Secondary Flow Development In A Cascade Like Passage Of A Turbomachine

1983 ◽  
pp. 11-23
Author(s):  
Amer Nordin Darus
Keyword(s):  
Experimental Data ◽  
Numerical Solution ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Rotational Flow ◽  
Simultaneous Solution ◽  
Analytical Formulation ◽  
Curved Duct ◽  
Flow Development ◽  
Vorticity Equations

Makalah ini memaparkan formulasi analitik dan penyelesaian numerik aliran dimensi tiga yang rotasional di dalam sebuah saluran yang melengkung. Formulasi ini berdasarkan perhitungan halaju aliran dan komponen vortisiti selari axis saluran tersebut. Halaju sekunder ditentukan melalui penyelesaian serentak persamaan-persamaan ke terusan dan vortisiti melalui penggunaan fungsi seperti fungsi arus. Hasil-hasil numerik diberikan dan dibandingkan dengan data-data eksperimen yang ada. This article presents the analytical formulation and numerical solution of the three-dimensional rotational flow in curved duct. The formulation is based on calculating the flow - wise velocity and vorticity. components from the momentum equation. The secondary velocities are determined from the simultaneous solution of the continuity and vorticity equations through the use of a streamlike function. The results presented arc compared with the existing experimental data.

Modelling Non-Uniform Bleed in Axial Compressors

2015 ◽  
Author(s):  
S. D. Grimshaw ◽  
G. Pullan ◽  
T. P. Hynes
Keyword(s):  
Experimental Data ◽  
Computational Cost ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Axial Distance ◽  
Two Dimensional ◽  
Flow Angle ◽  
Axial Compressors ◽  
Two Dimensional Flow ◽  
Satisfactory Prediction

The coupling between the bleed system and the flowfield of a downstream compressor stage is studied using two approaches. In the first, three-dimensional, full annulus, unsteady computations simulate the flow in a low speed research compressor with non-uniform bleed extraction. Comparisons with experimental data show that the flow prediction in the main annulus is accurate to within 0.005 of flow coefficient and 0.5° of flow angle. The CFD is then used to provide a description of flow within the bleed system itself. In the second approach, a two-dimensional mean radius model, similar to that adopted by Hynes and Greitzer in previous work on compressor stability, is used to simulate the response of the compressor to non-uniform bleed. This model is validated against experimental data for a single stage compressor and despite the inherent assumptions (two dimensional flow and simplified compressor response) provides a satisfactory prediction of the flow for preliminary design purposes with orders of magnitude less computational cost than full 3D CFD. The model is then used to investigate the effect of different levels of bleed non-uniformity and of varying the axial distance between the bleed and the downstream stage. Reducing bleed non-uniformity and moving the stage away from the bleed slot are predicted to reduce the circumferential non-uniformity of the flow entering the stage.

Diffusion rate influences on inter-turbine diffusers

1997 ◽  
Vol 211 (3) ◽  
pp. 235-242 ◽  
Author(s):  
G Norris ◽  
R G Dominy
Keyword(s):  
Fluid Dynamics ◽  
Diffusion Rate ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Low Energy ◽  
Experimental Measurements ◽  
Low Pressure Turbine ◽  
The Mean ◽  
Lp Turbine ◽  
Stage Efficiency

Inter-turbine diffusers are becoming of increasing importance to the aero gas turbine designer to diffuse the flow between the HP (high-pressure) or IP (intermediate-pressure) turbine and the LP (low-pressure) turbine. Diffusing the flow upstream of the LP turbine and raising the mean passage radius increases stage efficiency. These inter-turbine diffusers, which have high curvature, S-shaped geometry and low-energy wakes created by the upstream turbine, together give rise to secondary flows, making the flow fully three-dimensional. Using both experimental measurements and CFD (computational fluid dynamics) predictions, this paper demonstrates how the secondary flow behaviour is controlled by both the duct diffusion rate and upstream wake intensity.

Single Phase CFD Inside a Water Safety Valve

2010 ◽  
Author(s):  
Christophe Vallet ◽  
Je´roˆme Ferrari ◽  
Jean-Franc¸ois Rit ◽  
Fe´de´ric Dehoux
Keyword(s):  
Experimental Data ◽  
Single Phase ◽  
Safety Valve ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Water Safety ◽  
Relief Valve ◽  
Valve Opening

In this paper, Computational Fluid Dynamics (CFD) modeling is used to improve the understanding of the liquid flow inside a safety valve and to predict both the hydraulic force acting on the disk and the flow coefficient Cv. The three-dimensional simulations are performed on a realistic geometry and with an unstructured hybrid mesh. Independent calculations are performed for several valve openings. Turbulence is simulated using the Reynolds-Averaged Navier-Stokes (RANS) model k – ω SST, and a single-phase flow is considered for simplification. First, sensitivity of results with boundary conditions and mesh fineness is analysed. The dependence of hydraulic parameters with the valve opening is then investigated and numerical results are compared to experimental data coming from a test rig reproducing industrial conditions. Results indicate firstly that the flow inside the valve is stationary and axisymmetric. Quantitative comparison with the experiment must account for cavitation which is not simulated. We show, however, the adequacy of our results with experimental data and that single phase CFD can provide valuable insights on cavitating relief valve flow.

scholarly journals Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

2000 ◽  
Author(s):  
Daniel J. Dorney ◽  
Karen L. Gundy-Burlet
Keyword(s):  
Experimental Data ◽  
Surface Area ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Single Stage ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Strong Function ◽  
Hot Streak ◽  
Turbine Airfoils

Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

Numerical Simulation of Three-Dimensional Viscous Flow in a Linear Compressor Cascade With Tip Clearance

1996 ◽  
Vol 118 (3) ◽  
pp. 492-502 ◽  
Author(s):  
S. Kang ◽  
C. Hirsch
Keyword(s):  
Viscous Flow ◽  
Flow Structure ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Linear Compressor ◽  
Linear Compressor Cascade

A Navier–Stokes solver is applied to investigate the three-dimensional viscous flow in a low-speed linear compressor cascade with tip clearance at design and off-design conditions with two different meshes. The algebraic turbulence model of Baldwin–Lomax is used for closure. Relative motion between the blades and wall is simulated for one flow coefficient. Comparisons with experimental data, including flow structure, static and total pressures, velocity profiles, secondary flows and vorticity, are presented for the stationary wall case. It is shown that the code predicts well the flow structure observed in experiments and shows the details of the tip leakage flow and the leading edge horseshoe vortex.

scholarly journals Unsteady Numerical Simulations of Radial Temperature Profile Redistribution in a Single-Stage Turbine

1995 ◽  
Author(s):  
Daniel J. Dorney ◽  
John R. Schwab
Keyword(s):  
Experimental Data ◽  
Temperature Profile ◽  
Total Pressure ◽  
Three Dimensional ◽  
Temperature Gradients ◽  
Single Stage ◽  
Angle Distribution ◽  
Pressure Gradients ◽  
Flow Angle ◽  
Radial Temperature

Experimental data taken from gas turbine combustors indicate that the flow exiting the combustor can contain both circumferential and radial temperature gradients. A significant amount of research recently has been devoted to studying turbine flows with inlet temperature gradients, but no total pressure gradients. Less attention has been given to flows containing both temperature and total pressure gradients at the inlet. The significance of the total pressure gradients is that the secondary flows and the temperature redistribution process in the vane blade row can be significantly altered. Experimental data previously obtained in a single-stage turbine with inlet total temperature and total pressure gradients indicated a redistribution of the warmer fluid to the pressure surface of the airfoils, and a severe underturning of the flow at the exit of the stage. In a concurrent numerical simulation, a steady, inviscid, three-dimensional flow analysis was able to capture the redistribution process, but not the exit flow angle distribution. In the current research program, a series of unsteady two- and three-dimensional Navier-Stokes simulations have been performed to study the redistribution of the radial temperature profile in the turbine stage. The three-dimensional analysis predicts both the temperature redistribution and the flow underturning observed in the experiments.

scholarly journals Experimental Measurements of Rotordynamic Forces Caused by Front Shroud Pump Leakage

1999 ◽  
Vol 121 (3) ◽  
pp. 633-637 ◽  
Author(s):  
Robert V. Uy ◽  
Christopher E. Brennen
Keyword(s):  
Fluid Flow ◽  
Flow Coefficient ◽  
Leakage Flow ◽  
Experimental Measurements ◽  
Unsteady Forces ◽  
Leakage Path ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Flow Through ◽  
Rotordynamic Forces

Unsteady forces generated by fluid flow through the impeller shroud leakage path of a centrifugal pump were investigated. Different pump shroud geometries were compared, and the effect of leakage path inlet swirl (pump discharge swirl) on the rotordynamic forces was examined for various ratios of fluid throughflow velocity to impeller tip speed. A short axial length leakage path reduced the measured forces, while curvature appeared to increase the destabilizing forces when inlet swirl was present. It was observed that changing the inlet swirl velocity does not appear to significantly affect the measured forces for a given leakage flow coefficient, but any nonzero inlet swirl is destabilizing when compared to cases with no inlet swirl.

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