scholarly journals Effect of the Radial Pressure Gradient on the Secondary Flow Generated in an Annular Turbine Cascade

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Hesham M. El-Batsh
Keyword(s):  
Pressure Gradient ◽  
Secondary Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Radial Pressure ◽  
Navier Stokes ◽  
Pressure Probe ◽  
Passage Vortex ◽  
Flow Loss ◽  
Radial Pressure Gradient

This paper introduces an investigation of the effect of radial pressure gradient on the secondary flow generated in turbine cascades. Laboratory measurements were performed using an annular sector cascade which allowed the investigation using relatively small number of blades. The flow was measured upstream and downstream of the cascade using a calibrated five-hole pressure probe. The three-dimensional Reynolds Averaged Navier Stokes equations were solved to understand flow physics. Turbulence was modeled using eddy-viscosity assumption and the two-equation Shear Stress Transport (SST)k-ωmodel. The results obtained through this study showed that the secondary flow is significantly affected by the pressure gradient along blade span. The experimental measurements and the numerical calculations predicted passage vortex near blade hub which had larger and stronger values than that predicted near blade tip. The loss distribution revealed that secondary flow loss was concentrated near blade hub. It is recommended that attempts of reducing secondary flow in annular cascade should put emphasis on the passage vortex near the hub.

The Importance of Circumferential Non-uniformities in a Passage-Averaged Quasi-Three-Dimensional Turbomachinery Design System

1986 ◽  
Vol 108 (2) ◽  
pp. 240-245 ◽  
Author(s):  
I. K. Jennions ◽  
P. Stow
Keyword(s):  
Pressure Gradient ◽  
Guide Vane ◽  
Three Dimensional ◽  
Radial Pressure ◽  
Turbine Rotor ◽  
Design System ◽  
Radial Pressure Gradient ◽  
Flow Effects ◽  
Nozzle Guide ◽  
Turbomachinery Design

The purpose of this paper is to show, for both rotating and non-rotating blade rows, the importance of including circumferential non-uniform flow effects in a quasi-three-dimensional blade design system. The paper follows from previous publications on the system in which the mathematical analysis and computerized system are detailed. Results are presented for a different stack of the nozzle guide vane presented previously and for a turbine rotor. In the former case it is again found that the blade force represents a major contribution to the radial pressure gradient, while for the rotor the radial pressure gradient is dominated by centrifugal effects. In both examples the effects of circumferential non-uniformities are detailed and discussed.

scholarly journals A Remark on the Regularity Criterion for the 3D Boussinesq Equations Involving the Pressure Gradient

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Zujin Zhang
Keyword(s):  
Pressure Gradient ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Boussinesq Equations ◽  
Regularity Criterion ◽  
Navier Stokes ◽  
Navier Stokes Equations

We consider the three-dimensional Boussinesq equations and obtain a regularity criterion involving the pressure gradient in the Morrey-Companato spaceMp,q. This extends and improves the result of Gala (Gala 2013) for the Navier-Stokes equations.

The Importance of Circumferential Non-Uniformities in a Passage-Averaged Quasi-Three-Dimensional Turbomachinery Design System

1985 ◽  
Author(s):  
I. K. Jennions ◽  
P. Stow
Keyword(s):  
Pressure Gradient ◽  
Guide Vane ◽  
Three Dimensional ◽  
Radial Pressure ◽  
Turbine Rotor ◽  
Design System ◽  
Radial Pressure Gradient ◽  
Flow Effects ◽  
Nozzle Guide ◽  
Turbomachinery Design

The purpose of this paper is to show, for both rotating and non-rotating blade rows, the importance of including circumferential non-uniform flow effects in a quasi-three-dimensional blade design system. The paper follows on from previous publications on the system in which the mathematical analysis and computerised system are detailed. Results are presented for a different stack of the nozzle guide vane presented previously and for a turbine rotor. In the former case it is again found that the blade force represents a major contribution to the radial pressure gradient, while for the rotor the radial pressure gradient it is dominated by centrifugal effects. In both examples the effects of circumferential non-uniformities are detailed and discussed.

Investigation of Through-Flow Hypothesis in a Turbine Cascade Using a 3D Navier-Stokes Computation

1993 ◽  
Author(s):  
G. Perrin ◽  
F. Leboeuf
Keyword(s):  
Kinetic Energy ◽  
Three Dimensional ◽  
Radial Pressure ◽  
Momentum Balance ◽  
Navier Stokes ◽  
Minor Role ◽  
Passage Vortex ◽  
Spatial Fluctuations ◽  
Flow Variables ◽  
A Minor

The results of a computation, performed with a three-dimensional Navier-Stokes computation at ONERA, have been averaged in the blade-to-blade direction; the spatial fluctuations around the averaged flow variables have also been determined. It has then been possible to estimate all terms in the average components of the momentum equations. The comparison of the two-dimensional balances of these three equations shows that the shear stress play a minor role in the momentum balance, except on the dissipation of the passage vortex kinetic energy downstream of the blade trailing edges. The kinetic energy of the spanwise component of the velocity spatial fluctuations has a very strong influence on the radial pressure gradient; it introduces a convection effect. This is a key effect for all these balances.

Investigation of Throughflow Hypothesis in a Turbine Cascade Using a Three-Dimensional Navier–Stokes Computation

1995 ◽  
Vol 117 (1) ◽  
pp. 126-132
Author(s):  
G. Perrin ◽  
F. Leboeuf
Keyword(s):  
Kinetic Energy ◽  
Three Dimensional ◽  
Radial Pressure ◽  
Momentum Balance ◽  
Navier Stokes ◽  
Minor Role ◽  
Passage Vortex ◽  
Spatial Fluctuations ◽  
Flow Variables ◽  
A Minor

The results of a computation, performed with a three-dimensional Navier–Stokes computation at ONERA, have been averaged in the blade-to-blade direction; the spatial fluctuations around the averaged flow variables have also been determined. It has then been possible to estimate all terms in the average components of the momentum equations. The comparison of the two-dimensional balances of these three equations shows that the shear stress plays a minor role in the momentum balance, except on the dissipation of the passage vortex kinetic energy downstream of the blade trailing edges. The kinetic energy of the spanwise component of the velocity spatial fluctuations has a very strong influence on the radial pressure gradient; it introduces a convection effect. This is a key effect for all these balances.

scholarly journals A regularity criterion for the Navier-Stokes equations in terms of the pressure gradient

2014 ◽  
Vol 12 (7) ◽  
Author(s):  
Stefano Bosia ◽  
Monica Conti ◽  
Vittorino Pata
Keyword(s):  
Pressure Gradient ◽  
Weak Solutions ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Regularity Criterion ◽  
Navier Stokes ◽  
Navier Stokes Equations

AbstractThe incompressible three-dimensional Navier-Stokes equations are considered. A new regularity criterion for weak solutions is established in terms of the pressure gradient.

Stator Wake Research in Axial-Radial Combined Compressor With Inlet Distortion

2013 ◽  
Author(s):  
Du Li ◽  
Dazhong Lao ◽  
Ben Zhao ◽  
Ce Yang
Keyword(s):  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Potential Effect ◽  
Navier Stokes ◽  
Flow Angle ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Inlet Conditions

A combined compressor consisting of an axial rotor, a stator and a centrifugal rotor was used in a vehicle engine turbocharger because of its better performance compared with a single stage compressor under space restrictions. There have been many studies on the inlet distortion effect on multistage axial compressors; however, few studies have been performed for axial-radial combined compressors. To investigate stator wake characteristics, an axial-radial compressor was unsteadily simulated with three-dimensional Reynolds averaged Navier–Stokes equations by “domain-scaling” the rotor/stator interface method under uniform, circumferential distorted and combined distorted total pressure inlet conditions. In addition to the axial-radial configuration, the unsteady method of analysis was applied to a stand-alone axial stage by the same unsteady method. A comparison shows that at the vane stator outlet, a radial distortion is formed and different total pressure loss occurs at different spans. The circumferential interfaces between the distorted and non-distorted regions generate different flow characteristics due to different pitchwise pressure gradient directions and the absence of a downstream rotor. The stator wake causes more flow loss in the distorted case but less flow angle fluctuation compared to the uniform inlet condition. The downstream potential effect and inlet distortion creates strong pressure pulsation at the stator blade surface. A stator wake oscillation characteristics study shows disturbing effects on the stator wake from the upstream axial rotor, and the downstream radial rotor acts differently both spanwise and pitchwise.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

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