Effects of Inlet Swirl Angle on Flow and Heat Transfer in Contoured Turbine Nozzle Guide Vanes

2001 ◽  
Author(s):  
Y.-L. Lin ◽  
H. J. Schock ◽  
T. I-P. Shih ◽  
R. S. Bunker
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Stokes Equations ◽  
Secondary Flows ◽  
Stagnation Zone ◽  
Transfer Coefficients ◽  
Pressure Surface ◽  
Flow And Heat Transfer ◽  
Swirl Angle ◽  
Inlet Swirl

Abstract Computations, based on the ensemble-averaged compressible Navier-Stokes equations closed by the shear-stress transport (SST) model of turbulence, were performed to investigate the effects of inlet swirl angle on the three-dimensional flow and heat transfer in two contoured endwall configurations. Swirl angles investigated include three constant angles (0°, 15°, 30°) and a linearly varying angle from +30° at one endwall to −30° at the other. For all swirl angles, the mass-flow rate through the nozzle was fixed so that the higher the swirl angle, the higher is the velocity magnitude. Of the two endwalls investigated, one has all of the contouring upstream of the airfoil (C1), and another has contouring that starts upstream of the airfoil and continues until the airfoil’s trailing edge (C2). Computed results show that at all swirl angles investigated, the C2 configuration was able to reduce significantly secondary flows on the contoured endwall. Results also show that with reduced secondary flows, the heat-transfer coefficients are also reduced on the suction surface next to the juncture, where the airfoil meets the contoured endwall. On aerodynamics, the C2 configuration was found to produce essentially the same lift as the C1 configuration, but does so with less loss in stagnation pressure. For the C1 configuration, secondary flows are quite pronounced, and they increase slightly in size and in magnitude when swirl angle is increased. However, aerodynamic loss and surface heat transfer were found to decrease with increase in swirl angle. One explanation is that increasing the swirl angle shifted the stagnation zone downstream on the pressure surface to a flatter portion of the airfoil, producing a thicker boundary layer at the stagnation zone, and this changed considerably the evolution of the turbulent boundary layer. When the swirl angle varied linearly from +30° to −30°, increasing the velocity component towards the pressure surface was found to enhance instead of suppress the formation of secondary flows.

Controlling Secondary-Flow Structure by Leading-Edge Airfoil Fillet and Inlet Swirl to Reduce Aerodynamic Loss and Surface Heat Transfer

2002 ◽  
Author(s):  
T. I.-P. Shih ◽  
Y.-L. Lin
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Leading Edge ◽  
Surface Heat ◽  
Secondary Flows ◽  
Maximum Height ◽  
Surface Heat Transfer ◽  
Aerodynamic Loss ◽  
Swirl Angle ◽  
Inlet Swirl

Computations, based on the ensemble-averaged compressible Navier-Stokes equations closed by the shear-stress transport (SST) turbulence model, were performed to investigate the effects of leading-edge airfoil fillet and inlet-swirl angle on the flow and heat transfer in a turbine-nozzle guide vane. Three fillet configurations were simulated: no fillet (baseline), a fillet whose thickness fades on the airfoil, and a fillet whose thickness fades on the endwall. For both fillets, the maximum height above the endwall is positioned along the stagnation zone/line on the airfoil under the condition of no swirl. For each configuration, three inlet swirls were investigated: no swirl (baseline) and two linearly varying swirl angle from one endwall to the other (+30° to −30° and −30° to +30°). Results obtained show that both leading-edge fillet and inlet swirl can reduce aerodynamic loss and surface heat transfer. For the conditions of this study, the difference in stagnation pressure from the nozzle’s inlet to its exit were reduced by more than 40% with swirl or with fillet without swirl. Surface heat transfer was reduced by more than 10% on the airfoil and by more than 30% on the endwalls. When there is swirl, leading-edge fillets became less effective in reducing aerodynamic loss and surface heat transfer, because the fillets were not optimized for swirl angles imposed. Since the intensity and size of the cross flow were found to increase instead of decrease by inlet swirl and by the type of fillet geometries investigated, the results of this study indicate that the mechanisms responsible for aerodynamic loss and surface heat transfer are more complex than just the intensity and the magnitude of the secondary flows. This study shows their location and interaction with the main flow to be more important, and this could be exploited for positive results.

Controlling Secondary-Flow Structure by Leading-Edge Airfoil Fillet and Inlet Swirl to Reduce Aerodynamic Loss and Surface Heat Transfer

2003 ◽  
Vol 125 (1) ◽  
pp. 48-56 ◽  
Author(s):  
T. I-P. Shih ◽  
Y.-L. Lin
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Leading Edge ◽  
Surface Heat ◽  
Secondary Flows ◽  
Maximum Height ◽  
Surface Heat Transfer ◽  
Aerodynamic Loss ◽  
Swirl Angle ◽  
Inlet Swirl

Computations, based on the ensemble-averaged compressible Navier-Stokes equations closed by the shear-stress transport (SST) turbulence model, were performed to investigate the effects of leading-edge airfoil fillet and inlet-swirl angle on the flow and heat transfer in a turbine-nozzle guide vane. Three fillet configurations were simulated: no fillet (baseline), a fillet whose thickness fades on the airfoil, and a fillet whose thickness fades on the endwall. For both fillets, the maximum height above the endwall is positioned along the stagnation zone/line on the airfoil under the condition of no swirl. For each configuration, three inlet swirls were investigated: no swirl (baseline) and two linearly varying swirl angle from one endwall to the other (+30 to −30 deg and −30 to +30 deg). Results obtained show that both leading-edge fillet and inlet swirl can reduce aerodynamic loss and surface heat transfer. For the conditions of this study, the difference in stagnation pressure from the nozzle’s inlet to its exit were reduced by more than 40% with swirl or with fillet without swirl. Surface heat transfer was reduced by more than 10% on the airfoil and by more than 30% on the endwalls. When there is swirl, leading-edge fillets became less effective in reducing aerodynamic loss and surface heat transfer, because the fillets were not optimized for swirl angles imposed. Since the intensity and size of the cross flow were found to increase instead of decrease by inlet swirl and by the type of fillet geometries investigated, the results of this study indicate that the mechanisms responsible for aerodynamic loss and surface heat transfer are more complex than just the intensity and the magnitude of the secondary flows. This study shows their location and interaction with the main flow to be more important, and this could be exploited for positive results.

Mixed Convective Heat Transfer From Rotating Spheres

1998 ◽  
Author(s):  
Ali Heydari ◽  
Bahar Firoozabadi ◽  
Hamid Fazelli
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Transfer Coefficients ◽  
Navier Stokes Equations ◽  
Flow And Heat Transfer ◽  
Layer Flow

Abstract This paper presents an analysis of flow and heat transfer over a rotating axsisymmetric body of revolution in a mixed convective heat transfer along with surface conditions of heating or cooling as well as surface transpriation. Boundary-layer approximation reduces the elliptic Navier-Stokes equations to parabolic equations, where the Keller-Cebeci method of finite-difference solution is used to solve the resulting system of partial-differential equations. Comparison of the calculated values of the velocity and temperature profiles as well as the shear and the heat transfer coefficients at the surface for the case of a sphere with the available literature data indicate the model well predicts the boundary-layer flow and heat transfer over a rotating axsisymmetric body.

scholarly journals Measurement of Unsteady Flow and Heat Transfer in a Linear Turbine Cascade

1992 ◽  
Author(s):  
X. Liu ◽  
W. Rodi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Unsteady Flow ◽  
Boundary Layers ◽  
Suction Side ◽  
Turbine Cascade ◽  
Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Background Turbulence ◽  
Hot Film

A detailed experimental study has been conducted on the wake-induced unsteady flow and heat transfer in a linear turbine cascade. The unsteady wakes with passing frequencies in the range zero to 240 Hz were generated by moving cylinders on a squirrel cage device. The velocity fields in the blade-to-blade flow and in the boundary layers were measured with hot-wire anemometers, the surface pressures with a pressure transducer and the heat transfer coefficients with a glue-on hot film. The results were obtained in ensemble-averaged form so that periodic unsteady processes can be studied. Of particular interest was the transition of the boundary layer. The boundary layer remained laminar on the pressure side in all cases and in the case without wakes also on the suction side. On the latter, the wakes generated by the moving cylinders caused transition, and the beginning of transition moves forward as the cylinder-passing frequency increases. Unlike in the flat-plate study of Liu and Rodi (1991a) the instantaneous boundary layer state does not respond to the passing wakes and therefore does not vary with time. The heat transfer increases under increasing cylinder-passing frequency even in the regions with laminar boundary layers due to the increased background turbulence.

Nonaxisymmetric Three-Dimensional Stagnation-Point Flow and Heat Transfer on a Flat Plate

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Ali Shokrgozar Abbassi ◽  
Asghar Baradaran Rahimi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flat Plate ◽  
Stagnation Point ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Stagnation Point Flow ◽  
Navier Stokes ◽  
Dimensional Flow ◽  
Flow And Heat Transfer

The existing solutions of Navier–Stokes and energy equations in the literature regarding the three-dimensional problem of stagnation-point flow either on a flat plate or on a cylinder are only for the case of axisymmetric formulation. The only exception is the study of three-dimensional stagnation-point flow on a flat plate by Howarth (1951, “The Boundary Layer in Three-Dimensional Flow—Part II: The Flow Near Stagnation Point,” Philos. Mag., 42, pp. 1433–1440), which is based on boundary layer theory approximation and zero pressure assumption in direction of normal to the surface. In our study the nonaxisymmetric three-dimensional steady viscous stagnation-point flow and heat transfer in the vicinity of a flat plate are investigated based on potential flow theory, which is the most general solution. An external fluid, along z-direction, with strain rate a impinges on this flat plate and produces a two-dimensional flow with different components of velocity on the plate. This situation may happen if the flow pattern on the plate is bounded from both sides in one of the directions, for example x-axis, because of any physical limitation. A similarity solution of the Navier–Stokes equations and energy equation is presented in this problem. A reduction in these equations is obtained by the use of appropriate similarity transformations. Velocity profiles and surface stress-tensors and temperature profiles along with pressure profile are presented for different values of velocity ratios, and Prandtl number.

Numerical Simulation of Three-Dimensional Separated Flow and Heat Transfer Around a Surface-Mounted Square Plate

2003 ◽  
Author(s):  
Hiroyuki Yoshikawa ◽  
Keisuke Shimizu ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Separated Flow ◽  
Numerical Calculations ◽  
Flow And Heat Transfer ◽  
Square Plate ◽  
Separated And Reattached Flow

Direct Numerical Simulation results of three-dimensional laminar separated and reattached flow and heat transfer around a surface-mounted square plate are presented in this paper. Numerical calculations of Navier-Stokes equations and energy one are carried out using the finite difference method with SMAC method. A square plate is presumed to be mounted in a laminar boundary layer developing on a flat surface and to be heated under a constant heat flux. Numerical calculations are made on two boundary layer thicknesses at the plate, and the Reynolds number is varied from 300 to 1000. Details of the separated and reattached flow and the thermal field therein are clarified.

scholarly journals Fluid Flow and Heat Transfer Prediction in a Non-Rotating Axial Turbine Internal Coolant Passage and Comparison With Experiment

1993 ◽  
Author(s):  
W. N. Dawes ◽  
A. J. White
Keyword(s):  
Heat Transfer ◽  
General Purpose ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Transfer Coefficients ◽  
Absolute Level ◽  
Flow Solver ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Unstructured Meshing

This paper describes the application of an unstructured mesh, solution-adaptive, 3D Navier-Stokes solver to the numerical simulation of the flow in a complex, three pass, turbulated, serpentine coolant passage, typical of modern axial gas turbine practice. The predicted variation of heat transfer coefficient on the convex, pressure side of the passage is in encouraging agreement with measurements from a very similar geometry, particularly as regards spatial distribution. The absolute level of the predicted heat transfer coefficients is somewhat lower than in the measurements but this is consistent with the post-processing difficulty of defining the temperature difference used to form the coefficient. A strong inter-relationship was observed between the secondary flows in the coolant passage and the heat transfer distribution. The paper attempts to show that the benefits of unstructured meshing, solution-adaption and a general purpose flow solver combine to produce a very powerful analytical ability which now permits routine solution of complex geometries such as that described here.

scholarly journals Magnetohydrodynamic slip flow and heat transfer over a nonlinear shrinking surface in a heat generating fluid

2020 ◽  
Vol 9 (2) ◽  
pp. 534
Author(s):  
Leli Deswita ◽  
Mohamad Mustaqim Junoh ◽  
Fadzilah Md Ali ◽  
Roslinda Nazar ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Slip Flow ◽  
Transfer Coefficients ◽  
Suction Parameter ◽  
Boundary Layer Equations ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Layer Flow ◽  
Shrinking Surface

In this paper, the problem of steady slip magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a nonlinear permeable shrinking surface in a heat generating fluid is studied. The transformed boundary layer equations are then solved numerically using the bvp4c function in MATLAB solver. Numerical results are obtained for various values of the magnetic parameter, the slip parameter and the suction parameter. The skin friction coefficients, the heat transfer coefficients, as well as the velocity and temperature profiles for various values of parameters are also obtained and discussed. 

scholarly journals Computation of Flow and Heat Transfer in Rotating Two-Pass Square Channels by a Reynolds Stress Model

1999 ◽  
Author(s):  
Hamn-Ching Chen ◽  
Yong-Jun Jang ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Stress ◽  
Stokes Equations ◽  
Secondary Flows ◽  
Moment Closure ◽  
Closure Model ◽  
Second Moment ◽  
Flow And Heat Transfer ◽  
Second Moment Closure ◽  
Near Wall

A multiblock numerical method has been employed for the calculation of three-dimensional flow and heat transfer in rotating two-pass square channels with smooth walls. The finite-analytic method solves Reynolds-Averaged Navier-Stokes equations in conjunction with a near-wall second-order Reynolds stress (second-moment) closure model and a two-layer k–ε isotropic eddy viscosity model. Comparison of second-moment and two-layer calculations with experimental data clearly demonstrate that the secondary flows in rotating two-pass channels have been strongly influenced by the Reynolds stress anisotropy resulting from the Coriolis and centrifugal buoyancy forces as well as the 180° wall curvatures. The near-wall second-moment closure model provides the most reliable heat transfer predictions which agree well with measured data.

Sign in / Sign up

Export Citation Format

Share Document