scholarly journals Risk factor for central to radial pressure gradient in cardiac surgery

2008 ◽  
Vol 55 (S1) ◽  
pp. 4758721-4758721
Author(s):  
Antonio Su ◽  
André Denault ◽  
Alain Deschamps ◽  
Giuseppe Fuda ◽  
Jean Lambert ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Risk Factor ◽  
Pressure Gradient ◽  
Radial Pressure ◽  
Radial Pressure Gradient

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 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 EFFECT OF MIDAZOLAM-FENTANYL ANESTHESIA OF THE AORTO-RADIAL PRESSURE GRADIENT AFTER CPB

1998 ◽  
Vol 89 (Supplement) ◽  
pp. 279A
Author(s):  
A. Yazigi ◽  
F. Haddad ◽  
S. Madi-Jebara ◽  
G. Hayek ◽  
M. C. Antakly
Keyword(s):  
Pressure Gradient ◽  
Radial Pressure ◽  
Radial Pressure Gradient

Influences of Inlet Swirl Distributions on an Inter-Turbine Duct: Part I—Casing Swirl Variation

2011 ◽  
Author(s):  
Shuzhen Hu ◽  
Yanfeng Zhang ◽  
Xue Feng Zhang ◽  
Edward Vlasic
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flow Behavior ◽  
Radial Pressure ◽  
Boundary Layer Separation ◽  
Wake Flow ◽  
Layer Separation ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Radial Pressure Gradient

The inter-turbine transition duct (ITD) of a gas turbine engine has significant potential for engine weight reduction and/or aerodynamic performance improvement. This potential arises because very little is understood of the flow behavior in the duct in relation to the hub and casing shapes and the flow entering the duct (e.g., swirl angle, turbulence intensity, periodic unsteadiness and blade tip vortices from upstream HP turbine blade rows). In this study, the flow development in an ITD with different inlet swirl distributions was investigated experimentally and numerically. The current paper, which is the first part of a two-part paper, presents the investigations of the influences of the casing swirl variations on the flow physics in the ITD. The results show a fair agreement between the predicted and experimental data. The radial pressure gradient at the first bend of ITD drives the low momentum hub boundary layer and wake flow radially, which results in a pair of hub counter-rotating vortices. Furthermore, the radially moving low momentum wake flow feeds into the casing region and causes 3D casing boundary layer. At the second bend, the reversed radial pressure gradient together with the 3D casing boundary layer generates a pair of casing counter-rotating vortices. Due to the local adverse pressure gradient, 3D boundary layer separation occurs on both the casing and hub at the second bend and the exit of the ITD, respectively. The casing 3D separation enhances the 3D features of the casing boundary layer as well as the existing casing counter-rotating vortices. With increasing casing swirl angle, the casing 3D boundary layer separation is delayed and the casing counter-rotating vortices are weakened. On the other hand, although the hub swirls are kept constant, the hub counter-rotating vortices get stronger with the increasing inlet swirl gradient. The total pressure coefficients within the ITD are significantly redistributed by the casing and hub counter-rotating vortices.

Showerhead film cooling injection orientation design on the turbine vane leading edge considering representative lean burn combustor outflow

2021 ◽  
pp. 095441002199656
Author(s):  
Zhuang Wu ◽  
Hui-ren Zhu ◽  
Cun-liang Liu ◽  
Lin Li ◽  
Xu-yang Liu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Gradient ◽  
Film Cooling ◽  
Design Principle ◽  
Leading Edge ◽  
Radial Pressure ◽  
Mass Ratio ◽  
Lean Burn ◽  
Radial Pressure Gradient

The heat transfer performance of showerhead film cooling on the vane leading edge was numerically investigated considering representative lean burn combustor swirling outflow. Three cases with different inflow conditions (uniform inflow, positive swirling inflow, and negative swirling inflow) and three cases with different film injection angles (45°, 90°, and 135°) were studied. As the first study to explore the showerhead film design principle under swirling inflow, a newly designed asymmetrical counter-inclined (45° and 135°) film cooling was also proposed. To examine the design principles, the cooling effectiveness, heat transfer augmentation, and heat flux reduction of the newly designed asymmetrical case were evaluated compared with the traditional symmetrical case. The results show that the swirling inflow introduces obvious radial pressure gradient on the vane. The radial pressure gradient is the key influence factor to deflect the coolant migration, decrease the cooling effect, and degrade the homogeneity. The film with opposite orientation to the radial pressure gradient can weaken the deflect effect. The radial pressure gradient direction differs in different regions, making it impossible for the film with congruent injection orientation to simultaneously resist the pressure gradient on the entire vane. For the new design, the boundary line of the counter-inclined holes is consistent with the twisted stagnation line to guarantee that the injection orientation of all the film holes is opposite to the radial pressure gradient. As expected, the new design can effectively weaken the deflection effect and show uniform film distribution. The higher coolant mass ratio provides more obvious enhancement effect. At coolant mass ratio 3.71% and 4.56%, the overall area-averaged heat flux reduction (Δ q) is increased by 0.311 and 0.576, and the overall area-averaged relative standard deviation is reduced by 12.17 and 11.66 compared with the traditional design. The results have confirmed the adaptability of the film design principle under swirling inflow.

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.

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