The Research of Navigation Flow Conditions and Improvement Measures on Entrance Area and Connecting Reach of Dahua Lock in Hongshui River

2011 ◽  
Vol 250-253 ◽  
pp. 3624-3629
Author(s):  
Dian Guang Ma ◽  
Xin Liu ◽  
Jia Qiang Zhao ◽  
Xiao Fei Liu ◽  
Shao Xi Li
Keyword(s):  
Flow Conditions ◽  
Guangxi Province ◽  
Navigation Problem ◽  
Model Combining ◽  
Approach Channel ◽  
Improvement Measures ◽  
Navigation Lock ◽  
Lock In ◽  
Inflow Conditions ◽  
Pattern Problem

The ship facilities didn’t be constructed in step with the construction of Dahua Terminal in Hongshui River of Guangxi province, while the argumentation didn’t be carried out when navigation lock was built out. In the condition above, when the navigation lock was completed, the navigation flow conditions in the entrance area of downstream and the linkage section was bad, so ships were difficult to enter the approach channel. The research of navigation flow conditions and nay navigation mechanism in the entrance area of downstream and the linkage section in current condition was implemented through physical model combining ship model. The method of using traditional navigation wall and navigation pier to improve flow conditions didn’t be adopted in renovation research. The new renovation idea of changing inflow conditions was used innovatively and bad flow pattern problem was solved by using deep pools terrain in the entrance area of downstream. After the implementation of the engineering, nay navigation problem was solved effectively and ships could pass the terminal successfully. This engineering provides a new way to solve similar terminal navigation problem.

scholarly journals Equilibrium scour morphology downstream of rock sills under unsteady flow conditions

2018 ◽  
Vol 40 ◽  
pp. 03004 ◽  
Author(s):  
Stefano Pagliara ◽  
Michele Palermo
Keyword(s):  
Unsteady Flow ◽  
Experimental Tests ◽  
Peak Discharge ◽  
Flow Conditions ◽  
Different Shapes ◽  
Equilibrium Morphology ◽  
Inflow Discharge ◽  
Inflow Conditions ◽  
Scour Morphology ◽  
Correct Design

The present study aims to analyze the equilibrium scour morphology occurring downstream of rock-made sills with different shapes, under different inflow conditions. Namely, experimental tests were conducted under both steady and unsteady flow conditions. In this last case, the peak discharge was kept the same as the respective base tests performed for steady flow conditions. The scour evolution was carefully monitored, as well as the main characteristic lengths of the scour hole (e.g., maximum scour depth and axial length). The inflow discharge characteristics were varied, i.e., the maximum peak discharge was reached by adopting different hydrographs, in order to test their influence on the equilibrium morphology. Experimental results showed significant similitudes in terms of equilibrium scour morphology between steady and unsteady flow conditions when the hydrograph duration is enough long. The results of the present study can be useful for a correct design of such structure typology in usual applications.

Analysis of Unsteady Hydrodynamics Related to Vortex Induced Vibrations on Bluff-Bodied Offshore Structure

2017 ◽  
Author(s):  
Mandar Tabib ◽  
Adil Rasheed ◽  
Franz Georg Fuchs
Keyword(s):  
Drag Coefficient ◽  
Vortex Shedding ◽  
Pulsation Frequency ◽  
Offshore Structure ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Vortex Induced Vibrations ◽  
Shedding Frequency ◽  
Lock In ◽  
Inflow Conditions

Flows around a fixed cylinder with uniform and pulsating inflow conditions at different Reynolds numbers are simulated using Large Eddy Simulation (LES). For pulsating inflow, a sinusoidal profile, with an amplitude ΔU and a pulsation frequency fe, is superimposed onto the mean velocity U∞ at the inlet plane. The current study reveals that the pulsation can influence flow-physics in three possible ways as compared to uniform inflow conditions: (a) The vortex shedding pattern is seen to be more asymmetric for pulsating inflow than for uniform inflow. This needs to be validated with an experimental campaign devoted to the study of flow-asymmetricity due to pulsatile and uniform flow condition. (b) The dominant shedding frequency fd gets locked with respect to the frequency of the pulsating inflow fe, (for both the turbulent and transition regime) at a ratio of fe/fs0 equivalent to 0.65 – 0.75 (where fs0 is the vortex shedding frequency for uniform inflow) and ε = ΔU / (2πfeD) ≈ 0.2, where D is the diameter of the cylinder. This numerical observation is validated using the experimentally observed turbulent vortex regime work ( [1])in this range. For conditions with fe/fs0 > 0.75 the lock-in may happen at fe/2. (c) Compared to uniform inflow, the pulsating inflow leads to a larger drag coefficient. The drag coefficient is influenced by the ratios fe/fs0 and ΔU / U∞.

Flow Management in a Double-Offset, Transitional Twin Air-Intake at Different Inflow Conditions

2019 ◽  
Vol 12 (2) ◽  
pp. 168-179 ◽  
Author(s):  
Yadav K.K. Rajnath ◽  
Akshoy R. Paul ◽  
Anuj Jain
Keyword(s):  
Flow Control ◽  
Aerodynamic Performance ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Control Technique ◽  
Flow Conditions ◽  
Worst Case ◽  
Combat Aircraft ◽  
Air Intake ◽  
Inflow Conditions

Background: Transitional twin air-intake is a vital component of the air-induction system of single-engine combat aircraft. Combat aircraft do not always fly at steady, uniform flow conditions. But in some cases, it operates at different asymmetric flow conditions, which cause a change in aerodynamic performance of aircraft components like compressor and combustor. Objective: In order to improve the air quality at the outlet of air-intake- called Aerodynamic Inlet Plane (AIP) of this twin air-intake and to improve its aerodynamic performance for wide ranges of inflow conditions, slotted synthetic jets are used. Methods: Computational studies are carried out using Computational Fluid Dynamics (CFD) software for various types of skewed turbulent velocity profiles at inlet-2 with skewness number (ξ = 0, 0.3, 0.5, 0.7), while an average uniform velocity of 20m/s at inlet-1. Based on this analysis, worst case is selected and a pair of slotted synthetic jets is used just before the inflexion plane of the twin air-intake using transition SST turbulence model. Results: The flow behaviour of transitional twin air-intake becomes more complex with the increase in skewness number, thereby decreasing the aerodynamic performance of the air-intakes. With the use of slotted synthetic jets, an improvement in static pressure recovery and decrement in total pressure loss coefficient, distortion in coeffient swirl coefficient and secondary flow non-uniformity are observed which is a great sign of improved aerodynamic performance for the twin air-intakes. Conclusion: It is proved in this study that synthetic jet can be used effectively in twin air-intake to control the flow features leading to better flow uniformity and increased overall performance at the AIP without increasing the net-mass flow rate, thereby reducing the chance of stall/surge in the aeroengines. Hybrid flow control technique (synthetic jet coupled with vortex generator array) or newer flow control technique (plasma jet) are being explored for its possible use in engine air-intakes as revealed from recent patents filed/published in this area.

An Experimental Analysis of the Structural Response of Flexible Lightweight Hydrofoils in Cavitating Flow

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Alexandra Lelong ◽  
Pierre Guiffant ◽  
Jacques André Astolfi
Keyword(s):  
High Speed ◽  
Structural Response ◽  
Reynolds Numbers ◽  
Cavitating Flow ◽  
Static Deformation ◽  
Flow Conditions ◽  
Bending Mode ◽  
Measurement Laser ◽  
Lock In ◽  
Specific Distance

This paper presents an original experimental study concerning the structural response of a flexible lightweight hydrofoil undergoing various flow conditions including partial cavitating flow. It is based on the analysis of the static deformation, the vibrations, the strains, and the stresses of a polyacetal NACA0015 cantilevered hydrofoil in a hydrodynamic tunnel, at Reynolds numbers ranging from 3 × 105 to 6 × 105. A specific distance measurement laser device was developed to measure the static deformation of the hydrofoil. The vibration response was measured by means of two laser vibrometers in order to identify the structural modal response. The strains and stresses were obtained from integrated strain gauges embedded in the foil close to the root section. A high-speed camera was used in order to analyze unsteady features of the cavitating flow. This paper presents the experimental setup and several results in both noncavitating and cavitating flow that should be very useful for numerical developments of fluid structure interaction (FSI) in heavy fluid. Several observations are reported in the paper showing the strong coupling between the fluid and the structure. Particularly, a frequency lock-in of the cavity frequency to the first bending mode is clearly observed for a narrow band of cavitation numbers.

Influence of Waterproof Wall in Approach Channel of Double-Line Ship Lock on Flow Condition

2014 ◽  
Vol 716-717 ◽  
pp. 347-350
Author(s):  
Jun Tao Li ◽  
Wei Peng
Keyword(s):  
Flow Velocity ◽  
Flow Condition ◽  
Second Line ◽  
Hydraulic Characteristics ◽  
Xiangjiang River ◽  
Double Line ◽  
Approach Channel ◽  
Lock In ◽  
Transverse Flow Velocity ◽  
Ship Lock

Unsteady flow during lock filling and emptying in approach channel of double-line ship lock is more complicated than that of single line ship lock. In this paper, by a 3-D numerical model, the water fluctuation inside approach channel under different arrangement types of waterproof wall and the hydraulic characteristics such as longitudinal flow velocity and transverse flow velocity were analyzed on the basis of the 2000t second-line ship lock construction project of Zhuzhou navigation power junction in Xiangjiang River. According to the separate arrangement scheme and the completely-connected arrangement scheme of approach channel, the flow condition problem may exist in the scheme was analyzed. In order to improve the ship navigation and berthing condition, it was proposed that the waterproof wall should be set between the approach channels of the second-line ship lock.

A Single-Stage Centripetal Pump—Design Features and an Investigation of the Operating Characteristics

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Mihael Sekavčnik ◽  
Tine Gantar ◽  
Mitja Mori
Keyword(s):  
Single Stage ◽  
Flow Conditions ◽  
Operating Characteristics ◽  
Cfd Simulations ◽  
Pump Design ◽  
Flow Channels ◽  
Performance Curves ◽  
Computational Fluid Dynamics Cfd ◽  
Working Media ◽  
Inflow Conditions

In this paper, we present an experimental and numerical investigation of a single-stage centripetal pump (SSCP). This SSCP is designed to operate in the pump regime, while forcing the working media through impeller-stator flow channels in the radial inward direction. The measured performance curves are characterized by a hysteresis, since the throttle-closing performance curves do not correspond to the throttle-opening performance curves throughout the whole operating range. A computational fluid dynamics (CFD) model was developed to establish these throttle-closing and throttle-opening performance curves. The flow conditions obtained with the CFD simulations confirm that the hydraulic behavior of the SSCP is influenced by the partial circumferential stall that occurs in the impeller-stator flow channels. It was shown that the inflow conditions to the impeller-stator assembly considerably influence the flow rate of the stall cessation, the size of the hysteresis, and the head generated during part-load operations.

scholarly journals Understanding the Influence of Wake Cavitation on the Dynamic Response of Hydraulic Profiles under Lock-In Conditions

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6033
Author(s):  
Rafel Roig ◽  
Jian Chen ◽  
Oscar de la Torre ◽  
Xavier Escaler
Keyword(s):  
Dynamic Response ◽  
Power Systems ◽  
Sharp Decrease ◽  
Negative Consequences ◽  
Flow Conditions ◽  
Near Wake ◽  
Energy Technologies ◽  
Flow Phenomena ◽  
Shedding Frequency ◽  
Lock In

To accelerate the integration of fluctuating renewable energy technologies in the power systems, it is necessary to increase the flexibility of hydropower by operating turbines at off-design conditions. Unfortunately, this strategy causes deleterious flow phenomena such as von Kármán’s vortices at the wake of the vanes and/or blades. When their shedding frequency lies in the vicinity of a structure’s natural frequency, lock-in occurs and vibration amplitudes increase significantly. Moreover, if cavitation occurs at the centers of these vortices, the structure’s dynamic response will be modified. In order to understand this interaction and to avoid its negative consequences, the vibration behavior of a NACA 0009 hydrofoil under a torsional lock-in condition was numerically simulated for cavitation-free and cavitating-flow conditions. The results showed that the presence of vortex cavitation modified the formation and growth process of shed von Kármán vortices in the near-wake region which, in turn, caused an increase of the work performed by the hydrofoil deformation on the surrounding flow and a sharp decrease of the maximum vibration amplitude under resonance conditions.

Impact of Varying High- and Low-Pressure Turbine Purge Flows on a Turbine Center Frame and Low-Pressure Turbine System

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
P. Z. Sterzinger ◽  
S. Zerobin ◽  
F. Merli ◽  
L. Wiesinger ◽  
A. Peters ◽  
...  
Keyword(s):  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Flow Structures ◽  
Flow Conditions ◽  
High Pressure Turbine ◽  
Inlet Flow ◽  
Low Pressure Turbine ◽  
The Impact ◽  
Inflow Conditions

Abstract This paper presents the experimental and numerical evaluation and comparison of the different flow fields downstream of a turbine center frame duct and a low-pressure turbine (LPT) stage, generated by varying the inlet flow conditions to the turbine center frame (TCF) duct. The measurements were carried out in an engine-representative two-stage two-spool test turbine facility at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. The rig consists of a high-pressure turbine (HPT) and a LPT turbine stage, connected via a TCF with non-turning struts. Four individual high-pressure turbine purge flowrates and two low-pressure turbine purge flowrates were varied to achieve different engine-relevant TCF and LPT inlet flow conditions. The experimental data were acquired by means of five-hole-probe (5HP) area traverses upstream and downstream of the TCF and downstream of the LPT. A steady Reynolds-averaged Navier–Stokes (RANS) simulation taking all purge flows in account was used for comparison, and additional insights are gained from a numerical variation of the HPT and LPT purge flowrates. The focus of this study is on the impact of the variations in TCF inlet conditions on the secondary flow generation through the TCF duct and the carryover effects on the exit flow field and performance of the LPT stage. Existing work is limited by either investigating multistage LPT configurations with generally very few measurements behind the first stage or by not including relevant HPT secondary flow structures in setting up the LPT inflow conditions. This work addresses both of these shortcomings and presents new insight into the TCF and LPT aerodynamic behavior at varying the HPT and LPT purge flows. The results demonstrate the importance of the HPT flow structures and their evolution through the TCF duct for setting up the LPT inflow conditions and ultimately for assessing the performance of the first LPT stage.

scholarly journals Effects of the bottom slope and guiding wall length on the performance of a vortex drop inlet

2018 ◽  
Vol 78 (6) ◽  
pp. 1287-1295 ◽  
Author(s):  
Dong Sop Rhee ◽  
Yong Sung Park ◽  
Inhwan Park
Keyword(s):  
Water Surface ◽  
Laboratory Experiments ◽  
Surface Elevation ◽  
Design Criteria ◽  
Bottom Slope ◽  
Flow Conditions ◽  
Water Surface Elevation ◽  
Approach Channel ◽  
Maximum Water ◽  
Intake Structure

Abstract Laboratory experiments were conducted to assess the performance of a vortex drop inlet with a spiral intake in subcritical and supercritical flow conditions. The water surface elevation at multiple locations was measured for different flowrates by varying the extent of the guiding wall and the longitudinal and radial bottom slopes. The measurements show that a steeper longitudinal bottom slope decreases the water surface elevation at the beginning of the intake, resulting in a transcritical flow in the intake structure. However, a steeper longitudinal bottom slope also causes the maximum water surface elevation to occur within the spiral intake. For an effective vortex drop inlet design, achieving a low water surface elevation throughout the entire spiral intake structure is required. Experimental results show that the two seemingly conflicting design criteria, namely, achieving a low water surface elevation in the approach channel and reducing the maximum water surface elevation in the intake structure, can be simultaneously achieved by adding a radial bottom slope.

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