The Study on the Flow in a Horizontal Pump by 3D-PIV Experiments

2006 ◽  
Author(s):  
Yong Li ◽  
Hailin Pan ◽  
Yanming Wei ◽  
Shuhong Liu ◽  
Yulin Wu
Keyword(s):  
Free Surface ◽  
Chest Wall ◽  
Vortex Flow ◽  
Flow Conditions ◽  
3D Flow ◽  
Operation Conditions ◽  
Key Factor ◽  
Accessory Device ◽  
Pump Sump ◽  
Total Velocity

In order to investigate the flow conditions in a horizontal open pump sump, and to validate chest wall with different angles on preventing the vortex, and to find the key factor to the entrained vortex generating from the free surface, 3D PIV experiments were carried out in the pump sump. In the research, 3D PIV system was used to measure the flow near the free surface in the sump with different chest wall with angle of 0° and 30°. In the research, the refractivity-revised method was applied to get clear images in different media. In the method, an accessory device was used to eliminate the refractive effect between air and water. In the experiments, the multi-step calibrated method was applied to improve the measurement precision of the W vector. For each kind of chest wall, the experiments were performed under three operation conditions with different flow rates. From the experiments, the 3D flow conditions on the measuring plane can be obtained, such as velocity, streamline, and W velocity component. Analyzing those results, it can be concluded that the chest wall with angle of 30° can improve the flow conditions obviously and weaken the entrained vortex flow in the sump. Analyzing the experimental results, it can be found that the entrained vortex are more depended on ratio of the W velocity to the total velocity than other factors.

Avoiding Sedimentation and Air Entrainment in Pump Sump for Wet Pit Pumping Stations

2015 ◽  
Author(s):  
Raja Abou Ackl ◽  
Andreas Swienty ◽  
Flemming Lykholt-Ustrup ◽  
Paul Uwe Thamsen
Keyword(s):  
Physical Model ◽  
Air Entrainment ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Design Criteria ◽  
Flow Conditions ◽  
Pumping Station ◽  
Pumping Stations ◽  
Pump Sump ◽  
Pump Stations

In many places lifting systems represent central components of wastewater systems. Pumping stations with a circular wet-pit design are characterized by their relatively small footprint for a given sump volume as well as their relatively simple construction technique [1]. This kind of pumping stations is equipped with submersible pumps. These are located in this case directly in the wastewater collection pit. The waste water passes through the pump station untreated and loaded with all kind of solids. Thus, the role of the pump sump is to provide an optimal operating environment for the pumps in addition to the transportation of sewage solids. Understanding the effects of design criteria on pumping station performance is important to fulfil the wastewater transportation as maintenance-free and energy efficient as possible. The design of the pit may affect the overall performance of the station in terms of poor flow conditions inside the pit, non-uniform und disturbed inflow at the pump inlet, as well as air entrainment to the pump. The scope of this paper is to evaluate the impact of various design criteria and the operating conditions on the performance of pump stations concerning the air entrainment to the pump as well as the sedimentation inside the pit. This is done to provide documentation and recommendations of the design and operating of the station. The investigated criteria are: the inflow direction, and the operating submergence. In this context experiments were conducted on a physical model of duplex circular wet pit wastewater pumping station. Furthermore the same experiments were reproduced by numerical simulations. The physical model made of acrylic allowed to visualize the flow patterns inside the sump at various operating conditions. This model is equipped with five different inflow directions, two of them are tangential to the pit and the remaining three are radial in various positions relative to the pumps centerline. Particles were used to enable the investigation of the flow patterns inside the pit to determine the zones of high sedimentation risk. The air entrainment was evaluated on the model test rig by measuring the depth, the width and the length of the aerated region caused by the plunging water jet and by observing the air bubbles entering the pumps. The starting sump geometry called baseline geometry is simply a flat floor. The tests were done at all the possible combinations of inflow directions, submergence, working pump and operating flow. The ability of the numerical simulation to give a reliable prediction of air entrainment was assessed to be used in the future as a tool in scale series to define the scale effect as well as to analyze the flow conditions inside the sump and to understand the air entrainment phenomenon. These simulations were conducted using the geometries of the test setup after generating the mesh with tetrahedral elements. The VOF multiphase model was applied to simulate the interaction of the liquid water phase and the gaseous air phase. On the basis of the results constructive suggestions are derived for the design of the pit, as well as the operating conditions of the pumping station. At the end recommendations for the design and operating conditions are provided.

scholarly journals Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

2020 ◽  
Vol 16 ◽  
pp. 1924-1935
Author(s):  
Edgar Peris ◽  
Raúl Porcar ◽  
María Macia ◽  
Jesús Alcázar ◽  
Eduardo García-Verdugo ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Fine Tuning ◽  
Flow Conditions ◽  
Supported Ionic Liquid ◽  
Phosphine Complexes ◽  
Key Factor ◽  
Catalytic Cycles ◽  
Supported Ionic Liquids ◽  
Catch Mechanism

The combination of supported ionic liquids and immobilized NHC–Pd–RuPhos led to active and more stable systems for the Negishi reaction under continuous flow conditions than those solely based on NHC–Pd–RuPhos. The fine tuning of the NHC–Pd catalyst and the SILLPs is a key factor for the optimization of the release and catch mechanism leading to a catalytic system easily recoverable and reusable for a large number of catalytic cycles enhancing the long-term catalytic performance.

Investigation of Flow in a Steam Turbine Exhaust Hood With/Without Turbine Exit Conditions Simulated

2001 ◽  
Author(s):  
Jianjun Liu ◽  
Yongqiang Cui ◽  
Hongde Jiang
Keyword(s):  
Flow Pattern ◽  
Static Pressure ◽  
Navier Stokes ◽  
Steam Turbines ◽  
Exhaust Hood ◽  
Flow Conditions ◽  
3D Flow ◽  
Typical Design ◽  
Turbine Exhaust ◽  
Good Agreement

Experimental and numerical investigations for the flow in an exhaust hood model of large steam turbines have been carried out in order to understand the complex 3D flow pattern existing in the hood and also to validate the CFD solver. The model is a typical design for 300/600 MW steam turbines currently in operation. Static pressure at the diffuser tip and hub endwalls and at hood outer casing is measured and nonuniform circumferential distributions of static pressure are noticed. Velocity field at the model exit is measured and compared with the numerical prediction. The multigrid multiblock 3D Navier-Stokes solver used for the simulations is based upon the TVD Lax-Wendroff scheme and the Baldwin-Lomax turbulence model. Good agreement between numerical results and experimental data is demonstrated. It is found that the flow pattern and hood performance are very different with or without the turbine exit flow conditions simulated.

Investigation of the spark ignition enhancement in a supersonic flow

2014 ◽  
Vol 28 (29) ◽  
pp. 1450226 ◽  
Author(s):  
Zun Cai ◽  
Zhen-Guo Wang ◽  
Ming-Bo Sun ◽  
Hong-Bo Wang ◽  
Jian-Han Liang
Keyword(s):  
Ignition Time ◽  
Spark Ignition ◽  
Dominant Factor ◽  
Ignition Process ◽  
Operation Condition ◽  
Flame Kernel ◽  
Operation Conditions ◽  
Key Factor ◽  
Lean Fuel ◽  
Spark Energy

Ethylene spark ignition experiments were conducted based on an variable energy igniter at the inflow conditions of Ma = 2.1 with stagnation state T0 = 846 K , P0 = 0.7 MPa . By comparing the spark energy and spark frequency of four typical operation conditions of the igniter, it is indicated that the spark energy determines the scale of the spark and the spark existing time. The spark frequency plays a role of sustaining flame and promoting the formation and propagation of the flame kernel, and it is also the dominant factor determining the ignition time compared with the spark energy. The spark power, which is the product of the spark energy and spark frequency, is the key factor affecting the ignition process. For a fixed spark power, the igniter operation condition of high spark frequency with low spark energy always exhibits a better ignition ability. As approaching the lean fuel limit, only the igniter operation condition (87 Hz and 3.0 J) could achieve a successful ignition, where the other typical operation conditions (26 Hz and 10.5 J, 247 Hz and 0.8 J, 150 Hz and 1.4 J) failed.

scholarly journals Free-surface flows with near-critical flow conditions

1996 ◽  
Vol 23 (6) ◽  
pp. 1272-1284 ◽  
Author(s):  
H. Chanson
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Open Channel ◽  
Flow Instability ◽  
Open Channel Flow ◽  
Surface Characteristics ◽  
Free Surface Flows ◽  
Critical Flow ◽  
Flow Conditions ◽  
Weir Flow

Open channel flow situations with near-critical flow conditions are often characterized by the development of free-surface instabilities (i.e., undulations). The paper develops a review of several near-critical flow situations. Experimental results are compared with ideal-fluid flow calculations. The analysis is completed by a series of new experiments. The results indicate that, for Froude numbers slightly above unity, the free-surface characteristics are very similar. However, with increasing Froude numbers, distinctive flow patterns develop. Key words: open channel flow, critical flow conditions, free-surface undulations, flow instability, undular surge, undular broad-crested weir flow, culvert flow.

scholarly journals TURBULENCE IN THICK LAYERS

2012 ◽  
Vol 19 ◽  
pp. 390-395
Author(s):  
MICHAEL SHATS ◽  
HUA XIA ◽  
DAVID BYRNE
Keyword(s):  
Free Surface ◽  
Turbulent Flow ◽  
Decay Rate ◽  
Large Scale ◽  
New Physics ◽  
3D Flow ◽  
Coherent Vortices ◽  
Damping Rate ◽  
2D Flow ◽  
Thick Layers

Properties of turbulence, such as the direction of the energy cascade depend on the flow dimensionality. Recent experimental results reveal new physics understanding of flows in thick layers. We show that the flow dimensionality can be characterized by the flow damping and that a comparison of the decay rate with that of a quasi-2D flow can be used as a measure of dimensionality of a turbulent flow in a layer. This dimensionality, however can be strongly affected if large scale coherent vortices are present in the flow. These vortices can imposed twodimensionality and reduce the damping rate. Finally we show that even in thick layers with unperturbed free surface, turbulent flow can be viewed as co-existing 2D top sub-layer and the bulk 3D flow.

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