scholarly journals STUDY OF FLOW CHARACTERISTICS OF JUNCTION FLOW WITH FREE FLOW CONDITION AT BRANCH CHANNEL

2003 ◽  
Vol 47 ◽  
pp. 601-606
Author(s):  
Sunil Kumar LAMA ◽  
Keita KUDOH ◽  
Mikio KUROKI
Keyword(s):  
Flow Condition ◽  
Flow Characteristics ◽  
Free Flow ◽  
Junction Flow

Calibration 7" – Cutthroat Flume as New Size for Discharge Measurement at Free Flow Condition

2020 ◽  
Vol 38 (12A) ◽  
pp. 1783-1789
Author(s):  
Jaafar S. Matooq ◽  
Muna J. Ibraheem
Keyword(s):  
Steady State ◽  
Flow Condition ◽  
Laboratory Experiments ◽  
Free Flow ◽  
Experimental Program ◽  
Steady State Flow ◽  
Empirical Formulas ◽  
State Flow ◽  
Operation Conditions ◽  
Throat Width

 This paper aims to conduct a series of laboratory experiments in case of steady-state flow for the new size 7 ̋ throat width (not presented before) of the cutthroat flume. For this size, five different lengths were adopted 0.535, 0.46, 0.40, 0.325 and 0.27m these lengths were adopted based on the limitations of the available flume. The experimental program has been followed to investigate the hydraulic characteristic and introducing the calibrated formula for free flow application within the discharge ranged between 0.006 and 0.025 m3/s. The calibration result showed that, under suitable operation conditions, the suggested empirical formulas can accurately predict the values of discharge within an error ± 3%.

A particle image velocimetry study on the pulsatile flow characteristics in straight tubes with an asymmetric bulge

2000 ◽  
Vol 214 (5) ◽  
pp. 655-671 ◽  
Author(s):  
S C M Yu ◽  
J B Zhao
Keyword(s):  
Particle Image Velocimetry ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Condition ◽  
Particle Image ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Conditions ◽  
Image Velocimetry

Flow characteristics in straight tubes with an asymmetric bulge have been investigated using particle image velocimetry (PIV) over a range of Reynolds numbers from 600 to 1200 and at a Womersley number of 22. A mixture of glycerine and water (approximately 40:60 by volume) was used as the working fluid. The study was carried out because of their relevance in some aspects of physiological flows, such as arterial flow through a sidewall aneurysm. Results for both steady and pulsatile flow conditions were obtained. It was found that at a steady flow condition, a weak recirculating vortex formed inside the bulge. The recirculation became stronger at higher Reynolds numbers but weaker at larger bulge sizes. The centre of the vortex was located close to the distal neck. At pulsatile flow conditions, the vortex appeared and disappeared at different phases of the cycle, and the sequence was only punctuated by strong forward flow behaviour (near the peak flow condition). In particular, strong flow interactions between the parent tube and the bulge were observed during the deceleration phase. Stents and springs were used to dampen the flow movement inside the bulge. It was found that the recirculation vortex could be eliminated completely in steady flow conditions using both devices. However, under pulsatile flow conditions, flow velocities inside the bulge could not be suppressed completely by both devices, but could be reduced by more than 80 per cent.

scholarly journals Impact of Different Vegetation Zones on the Velocity and Discharge of Open-Channel Flow

2021 ◽  
Author(s):  
Xiaonan Tang ◽  
Yutong Guan ◽  
Yuxiang Hu
Keyword(s):  
Shear Layer ◽  
Management Practices ◽  
Open Channel ◽  
Flow Characteristics ◽  
Flow Region ◽  
Free Flow ◽  
Flow Process ◽  
Riparian Management ◽  
Free Zone ◽  
Rigid Vegetation

Different types of vegetation widely exist in rivers and wetlands. The vegetation will affect the ecological environment and flow process, thus becoming increasingly significant in river engineering and aquatic environmental management. Previous research on vegetated flow is mainly to understand the flow structure of open channels with fully covered one-layer vegetation. However, vegetation often grows along a river bank and co-exists in different heights. The present paper presents experimental results about the flow characteristics of an open-channel with two sides covered by differently layered vegetation, focusing on the effect of vegetation on the velocity distribution and discharge. Two heights of dowels in 10 cm and 20 cm were used to simulate rigid vegetation and arranged in a linear form on both sides of a channel bed under emergent and fully submerged flow conditions. The velocity at different positions was obtained using ADV (Acoustic Doppler Velocimetry). Measured results demonstrate that there exists a shear layer between free-flow and vegetated zones, indicating that the flow transition occurs between fast-moving flow in the free zone and slowly obstructed flow in the vegetated zone and induces a high shear layer and transverse coherent vortices near the interface. Furthermore, compared with the emergent condition, the discharge through the free-flow region slightly decreases under full submerged conditions while the discharge in the vegetated region increases, indicating that the vegetation does not significantly change the discharge percentage in the free region. These findings on differently-layered vegetation would help riparian management practices to maintain healthy ecological and habitat zones.

scholarly journals Modeling and Computation of Flow in a Passage With 360° Turning and Multiple Airfoils

1991 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Numerical Modeling ◽  
Detailed Analysis ◽  
Flow Condition ◽  
Global Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
The Individual ◽  
Spiral Casing

Numerical modeling of the three-dimensional flows in a spiral casing of a hydraulic turbine, containing a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor), is made. The physical model is based on a novel two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

Pressure-flow characteristics of coronary collaterals in dogs

1989 ◽  
Vol 256 (2) ◽  
pp. H441-H445 ◽  
Author(s):  
K. W. Scheel ◽  
H. Mass ◽  
S. E. Williams
Keyword(s):  
Isolated Heart ◽  
Flow Characteristics ◽  
Back Pressure ◽  
Free Flow ◽  
Flow Index ◽  
Collateral Flow ◽  
Retrograde Flow ◽  
Pressure Flow ◽  
Flow Method ◽  
Pressure Method

In this study we utilized two methods to investigate the pressure-flow, P-F, relationship of the coronary collateral vessels in a beating, blood-perfused, isolated heart preparation. In the first method (free-flow method), 12 dog hearts were perfused at pressures ranging from 100 to 0 mmHg, whereas the retrograde flow (index of collateral flow) was measured on the circumflex coronary artery, LCA, against atmospheric pressure, first during autoregulation and then after maximum vasodilation. In the second method (back-pressure method), the back pressure to retrograde flow was varied from 0 to 100 mmHg, whereas the perfusion pressure to the remaining vessels was maintained constant at 100 mmHg. This procedure was performed on four hearts with and without embolization of the LCA by 25-microns spheres. The free-flow method demonstrated a linear P-F relationship with an average correlation coefficient, r, of 0.98. The pressure intercept was 1.7 +/- 1.2 mmHg. The back-pressure method yielded a relationship that was more curvilinear with an average pressure intercept of 13 mmHg without embolization and 38 mmHg with embolization. An analog of the coronary and collateral circulation was used to illustrate that, in the back-pressure method, changes in the coronary resistance at low pressures contributed to the nonlinearity of the collateral P-F characteristics and that the network formed between the collateral and coronary resistances was responsible for the higher pressure intercept value.

Experimental and Numerical Investigation of Near-Tip Flow Field in an Axial Flow Compressor Rotor: Part II — Flow Characteristics at Stall Inception Condition

2013 ◽  
Author(s):  
Yanhui Wu ◽  
Junfeng Wu ◽  
Haoguang Zhang ◽  
Wuli Chu
Keyword(s):  
Flow Field ◽  
Flow Condition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Current Investigation ◽  
Flow Mechanism ◽  
Stall Inception ◽  
Compressor Rotor ◽  
Casing Pressure ◽  
Stable Flow

Systematical casing pressure measurements were undertaken to supplement instantaneous experiment data to available database of a high-speed small-scale compressor rotor, which was crucial for understanding the flow mechanism of short-length scale stall inception. At the same time, improved full-annulus simulations were conducted to assist in interpretation of experimental observations. In Part II of current investigation, original instantaneous casing pressure signals and STFT (short time Fourier transformation) analyses were conducted to conclude flow characteristics near casing at stall inception operating condition, and reasonable explanation of experimental observations was given in combination with numerical results. The current experimental investigation showed the stall inception of the test rotor was triggered by a spike, propagating at about 66.7%, which evolved into a single fully-developed stall cell. STFF analysis of pressure signal detected by probe located at tip leading edge showed that frequency peaks with varied band, which already observed in near-stall stable flow condition in Part I, was still a dominant flow feature before spike emergence, though it was hardly perceived after spike emergence due to a sudden increase in the overall energy of pressure signal, which attributed to the interface of incoming and tip clearance flow beyond leading edge plane according to STFT results. Monitoring results of static pressures in the absolute frame from current simulation and the corresponding FFT and STFT analyses showed a similar flow field evolution process as those observed in experiment. The current investigation provided adequate experimental evidence to support the previous simulation results in which a viewpoint of formation and activity of tip secondary vortex (TSV) was proposed as the underlying flow mechanism of the origin of unsteadiness near casing at near-stall stable operating conditions, and emergence of spike during the transition of flow field into unstable state, and further verified that the unsteady flow phenomenon observed in near-stall stable flow condition was equivalent to rotating instability (RI), thus establishing the causal linkage between RI and stall inception for the test rotor.

Sign in / Sign up

Export Citation Format

Share Document