scholarly journals PIV Investigation of the Flow Characteristics in an Internal Coolant Passage With 45deg Rib Arrangement

1999 ◽  
Author(s):  
J. Schabacker ◽  
A. Boelcs ◽  
B. V. Johnson
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Outer Wall ◽  
Secondary Flows ◽  
Mean Velocity ◽  
Piv Measurements ◽  
Working Medium ◽  
Staggered Arrangement ◽  
Flow Phenomena ◽  
Rib Arrangement

Flow characteristics in a model of a stationary two-pass internal coolant passage were measured with the stereoscopic PIV technique. From the PIV measurements, the 3D mean velocity field and turbulence quantities of the flow were obtained simultaneously with high spatial resolution, which allowed for an understanding of the flow phenomena in the coolant passage. The model of the coolant passage consists of two square legs, each having a length of 19 hydraulic diameters that are connected by a sharp 180deg bend with a rectangular outer wall. In the two legs, 45deg ribs are mounted in a staggered arrangement on the bottom and top wall, with rib heights equal to 0.1 hydraulic diameter, and rib spacing of 10 rib heights. The measurements were carried out for a Reynolds number of 45,700 with air as working medium. The paper presents results of the flow development in the straight legs of the passage and in the bend. The oblique ribs in the straight legs contribute to the development of secondary flows that transport fluid from the leg center towards the walls. In the bend of the passage, the interaction between rib-induced and bend-induced secondary flows leads to a three-dimensional flow. Downstream of the bend, the ribs quickly dominate the flow and thus lead to a fast recovery of the flow from the bend effect.

Flow Characteristics in Two-Leg Internal Coolant Passages of Gas Turbine Airfoils With Film-Cooling Hole Ejection

2002 ◽  
Vol 124 (3) ◽  
pp. 499-507 ◽  
Author(s):  
D. Chanteloup ◽  
A. Bo¨lcs
Keyword(s):  
Reynolds Number ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Outer Wall ◽  
Detailed Comparison ◽  
Mean Velocity ◽  
Cooling Channels ◽  
Staggered Arrangement ◽  
Cooling Hole ◽  
Turbine Airfoils

A study of flow in two stationary models of two-pass internal coolant passages is presented, which focuses on the flow characteristics in the 180-deg bend region, and downstream of the bend, where the flow is redeveloping. A stereoscopic digital PIV system measured all three velocity components simultaneously to obtain mean velocity, and turbulence quantities of the flow field. The coolant passage model consisted of two square passages, each having a 20 hydraulic diameter length, separated by a rounded-tip web of 0.2 passage widths, and connected by a sharp 180-deg bend with a rectangular outer wall. Ribs were mounted on the bottom and top walls of both legs, with a staggered arrangement, and at 45 deg to the flow. The rib height and spacing were 0.1 and 1.0 passage heights, respectively. The measurements were obtained for a flow condition, with a Reynolds number of 50,000. The geometries are similar in both sections except for one, which is equipped with extraction holes to simulate holes for film cooling. Two series of holes are placed solely in the bottom wall, four holes are located in the bend, and 12 in the downstream leg. The global extraction through the holes was set to 50% of the inlet massflow. This paper presents new measurements of the flow in the straight legs, as well as in the bend of the passage equipped with holes, detailed comparison of the flow upstream, inside and downstream of the bend region between both configurations, and the effects of extraction inside the cooling channels.

Combined 3D Flow and Heat Transfer Measurements in a 2-Pass Internal Coolant Passage of Gas Turbne Airfoils

2002 ◽  
Author(s):  
D. Chanteloup ◽  
Y. Juaneda ◽  
A. Bo¨lcs
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Outer Wall ◽  
Hydraulic Diameter ◽  
Secondary Flows ◽  
Thermochromic Liquid Crystal ◽  
Flow Measurements ◽  
Detailed Measurement ◽  
Flow And Heat Transfer ◽  
Staggered Arrangement

A study of the flow and heat transfer in a stationary model of a two-pass internal coolant passage is presented, which focuses on the flow characteristic effects on the wall heat transfer distribution. Results are given in the upstream fully developed region. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface temperature. The technique allows full surface heat transfer coefficient measurements on all the walls. Flow measurements were made with a stereoscopic digital PIV system, which measures all three-velocity components simultaneously. The coolant passage model consists of two square ducts, each having a 20 hydraulic diameter length. The ducts are connected by a sharp 180° bend with a rectangular outer wall. 45° ribs are mounted in a staggered arrangement on the bottom and top walls of both legs. The height of the ribs is equal to 0.1 hydraulic diameters. They are spaced 10 rib heights apart. The flow and heat transfer measurements were obtained at one flow condition with an inlet flow Reynolds number, based on the hydraulic diameter, of 50,000. The paper presents detailed measurement results of the flow characteristics and of the heat transfer distribution in the upstream straight leg of the passage and describes how the main and secondary flows influence the heat transfer distribution in the fully developed regions of the channel.

Pulsatile Non-Newtonian Flow Characteristics in a Three-Dimensional Human Carotid Bifurcation Model

1991 ◽  
Vol 113 (4) ◽  
pp. 464-475 ◽  
Author(s):  
K. Perktold ◽  
M. Resch ◽  
H. Florian
Keyword(s):  
Shear Stress ◽  
Carotid Sinus ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Outer Wall ◽  
Maximum Diameter ◽  
Newtonian Flow ◽  
Pulse Cycle ◽  
Flow Phenomena ◽  
Human Carotid

Numerical analysis of flow phenomena and wall shear stresses in the human carotid artery bifurcation has been carried out using a three-dimensional geometrical model. The primary aim of this study is the detailed discussion of non-Newtonian flow velocity and wall shear stress during the pulse cycle. A comparison of non-Newtonian and Newtonian results is also presented. The applied non-Newtonian behavior of blood is based on measured dynamic viscosity. In the foreground of discussion are the flow characteristics in the carotid sinus. The investigation shows complex flow patterns especially in the carotid sinus where flow separation occurs at the outer wall throughout the systolic deceleration phase. The changing sign of the velocity near the outer sinus wall results in oscillating shear stress during the pulse cycle. At the outer wall of the sinus at maximum diameter level the shear stress ranges from −1.92 N/m2 to 1.22 N/m2 with a time-averaged value of 0.04 N/m2. At the inner wall of the sinus at maximum diameter level the shear stress range is from 1.16 N/m2 to 4.18 N/m2 with a mean of 1.97 N/m2. The comparison of non-Newtonian and Newtonian results indicates unchanged flow phenomena and rather minor differences in the basic flow characteristics.

scholarly journals Combined 3-D Flow and Heat Transfer Measurements in a 2-Pass Internal Coolant Passage of Gas Turbine Airfoils

2002 ◽  
Vol 124 (4) ◽  
pp. 710-718 ◽  
Author(s):  
D. Chanteloup ◽  
Y. Juaneda ◽  
A. Bo¨lcs
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Outer Wall ◽  
Hydraulic Diameter ◽  
Secondary Flows ◽  
Thermochromic Liquid Crystal ◽  
Flow Measurements ◽  
Detailed Measurement ◽  
Flow And Heat Transfer ◽  
Staggered Arrangement

A study of the flow and heat transfer in a stationary model of a two-pass internal coolant passage is presented, which focuses on the flow characteristic effects on the wall heat transfer distribution. Results are given in the upstream fully developed region. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface temperature. The technique allows full surface heat transfer coefficient measurements on all the walls. Flow measurements were made with a stereoscopic digital PIV system, which measures all three-velocity components simultaneously. The coolant passage model consists of two square ducts, each having a 20 hydraulic diameter length. The ducts are connected by a sharp 180 deg bend with a rectangular outer wall. 45 deg ribs are mounted in a staggered arrangement on the bottom and top walls of both legs. The height of the ribs is equal to 0.1 hydraulic diameters. They are spaced 10 rib heights apart. The flow and heat transfer measurements were obtained at one flow condition with an inlet flow Reynolds number, based on the hydraulic diameter, of 50,000. The paper presents detailed measurement results of the flow characteristics and of the heat transfer distribution in the upstream straight leg of the passage and describes how the main and secondary flows influence the heat transfer distribution in the fully developed regions of the channel.

scholarly journals Hydrodynamics of an in-pond raceway system with an aeration plug-flow device for application in aquaculture: an experimental study

2019 ◽  
Vol 6 (7) ◽  
pp. 182061 ◽  
Author(s):  
Wuhua Li ◽  
Xiangju Cheng ◽  
Jun Xie ◽  
Zhaoli Wang ◽  
Deguang Yu
Keyword(s):  
Water Flow ◽  
Plug Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
High Water ◽  
Secondary Flows ◽  
Commercial Application ◽  
Flow Device ◽  
Intensive Aquaculture

An in-pond raceway system (IPRS) is an effective intensive aquaculture practice for regions with high water consumption and limited land resources. Water flow and dissolved oxygen (DO) are important for sustainable aquaculture. Several innovations have been made in IPRS design and operation to increase water exchange and DO concentration; one of these is the aeration plug-flow device (APFD). The APFD is commonly used in China as the only power source for water recirculation in aquaculture ponds. Understanding of the hydrodynamics of the system is necessary to improve the design of the IPRS with APFD. To this end, we performed experimental studies on a model system. We measured three-dimensional velocity at various locations using an Acoustic Doppler Velocimeter. Velocity distribution and turbulence characteristics were assessed, and plug-flow characteristics were analysed. Two patterns of velocity and turbulence in horizontal sections were observed: near the APFD, the water flow was intensively pushed downstream and simultaneously recirculated; farther away, the reflux area gradually decreased and the velocity and turbulence distribution trended towards uniform. Secondary flows occurred in different directions, which improved the diffusion of materials and DO retention. The system is effectively self-circulating, and the plug-flow capability may be scaled up for commercial application.

scholarly journals Flow-Induced Vibration on the Control Valve with a Different Concave Plug Shape Using FSI Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Akram Zeid ◽  
Mohamed Shouman
Keyword(s):  
High Efficiency ◽  
Complex Structure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Control Valve ◽  
Low Noise ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Flow Phenomena

Control valves have always been recognised as being among the most crucial control equipment, commonly utilised in versatile engineering applications. Hence, the need has arisen to identify the flow characteristics inside the valve, together with the incurred vibration induced as a result of the flow passing through the valve. Thanks to the tangible and fast progress made in the field of the flow simulation and numerical techniques, it has become possible to better observe the behavior of the flow passing inside a valve with view to examining its performance. Hence, the paper at hand is mainly concerned with introducing the modeling and simulation of a control valve. On the contrary, the flow system in a control valve is marked by a complex structure and nonlinear characteristics. The reasons for those qualities could be attributed to its construction as well as the fluid flow phenomena associated with it. It is especially for the sake of investigating and observing the flow characteristics, pertaining to a control valve equipped with different concave plug shapes and different openings, that the three-dimensional FSI simulation is conducted. In addition, it would be possible to make use of the obtained results relating to the three-dimensional analysis to achieve low noise and high efficiency improvement. Furthermore, all results will be validated on experimental grounds.

PIV Measurements in Diffuser of the Radial Pump

2015 ◽  
Author(s):  
Sung Yong Jung ◽  
Young Uk Min ◽  
Kyung Lok Lee
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Internal Flows ◽  
Piv Measurements ◽  
Image Velocimetry ◽  
Acquisition Device ◽  
Field Information ◽  
Radial Pump

The performance characteristics of the radial pump commonly used as a multistage (8 or 10 stage) pump have been investigated experimentally. Due to the complex three-dimensional geometries, the hydraulic performance of multistage pumps is closely related to the internal flows in diffuser and return vanes. In order to investigate the flow characteristics in these regions by Particle Image Velocimetry (PIV) technique, a transparent pump is designed. A 532 nm continuous laser and a high-speed camera are used as a light source and an image acquisition device, respectively. The velocity field information in a diffuser of the radial pump is successfully obtained by two-dimensional PIV measurements at various operating conditions.

Numerical Study of Turbulent Flow and Convective Heat Transfer Characteristics in Helical Rectangular Ducts

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Yunfei Xing ◽  
Fengquan Zhong ◽  
Xinyu Zhang
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Outer Wall ◽  
Centrifugal Effect

Three-dimensional turbulent forced convective heat transfer and its flow characteristics in helical rectangular ducts are simulated using SST k–ω turbulence model. The velocity field and temperature field at different axial locations along the axial direction are analyzed for different inlet Reynolds numbers, different curvatures, and torsions. The causes of heat transfer differences between the inner and outer wall of the helical rectangular ducts are discussed as well as the differences between helical and straight duct. A secondary flow is generated due to the centrifugal effect between the inner and outer walls. For the present study, the flow and thermal field become periodic after the first turn. It is found that Reynolds number can enhance the overall heat transfer. Instead, torsion and curvature change the overall heat transfer slightly. But the aspect ratio of the rectangular cross section can significantly affect heat transfer coefficient.

SIMULATION OF VESSEL STRESS AND SECONDARY FLOWS FOR BLOOD FLOWS THROUGH A REALISTIC AORTA WITH THREE BRANCHES

2007 ◽  
Vol 19 (04) ◽  
pp. 215-223 ◽  
Author(s):  
Yang-Yao Niu ◽  
Pang-Chung Wu ◽  
Wen-Yih I. Tseng ◽  
Hsi-Yu Yu
Keyword(s):  
Secondary Flow ◽  
Aortic Arch ◽  
Three Dimensional ◽  
Wall Stress ◽  
Outer Wall ◽  
Secondary Flows ◽  
Blood Flows ◽  
Flow Recirculation ◽  
Dimensional Reconstruction

Blood secondary flows and vessel wall shear stress distributions in a human aortic arch have been predicted numerically for a Reynolds number of 4700 at entrance. The simulation geometry was derived from a three-dimensional reconstruction of a series of two-dimensional slices obtained in vivo. Numerical results demonstrate wall stresses were highly dynamic, but were generally high along the outer wall in the vicinity of the branches and low along the inner wall, particularly in the descending thoracic aorta. The maximum wall stress distribution is presented on the aortic arch in the systole. Extensive secondary flow motion was observed in the aorta, and the structure of these secondary flows was influenced considerably by the presence of the branches. Within the aorta, it is observed that clockwise secondary flow recirculation, also seen in the MRA scan data, appears in the downstream of aortic arch in the late systole and turn out to be a pair of counter-clockwise vortex in the downstream of the arch in the early diastole.

New Methods for Secondary Flow Phenomena Visualization and Analysis

2019 ◽  
Author(s):  
Mattia Straccia ◽  
Rodolfo Hofmann ◽  
Volker Gümmer
Keyword(s):  
Secondary Flow ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Secondary Flows ◽  
Tip Leakage ◽  
Ansys Cfx ◽  
Flow Phenomena ◽  
Visualization Techniques ◽  
Operating Points

Abstract This work focuses on presenting new techniques for the visualization of Secondary Flow Phenomena (SFP) in transonic turbomachinery. Here, Rotor 37 has been used to develop and apply these techniques in order to study vortices, shocks and secondary flows. They are also used to provide a comparison between turbulence models in Ansys CFX environment, here the Spalart-Allmaras (SA) and Shear Stress Tensor (SST) turbulence models. The scope of this paper is to give an improved understanding of SFP and how their onset and evolution are influenced from the turbulence model. The analysis is based on results of three-dimensional steady-state RANS simulations, for operating points between design point and near-stall condition, achieved by varying the outlet static pressure radial equilibrium distribution at the rotor exit. The new visualization techniques highlight important flow field features less investigated in previous research works, in particular secondary weak strength vortices. They will give a better visualization of and insight to the interaction of the passage shock and the tip leakage vortex, the interaction between vortices and boundary layers and the interaction of the shock wave and endwall boundary layers.

Sign in / Sign up

Export Citation Format

Share Document