scholarly journals Study on the Transient Characteristics of the Centrifugal Pump during the Startup Period with Assisted Valve

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1241
Author(s):  
Qiao Li ◽  
Xiang Ma ◽  
Peng Wu ◽  
Shuai Yang ◽  
Bin Huang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Transient Behavior ◽  
Hydrodynamic Performance ◽  
Rotational Inertia ◽  
Strong Response ◽  
Large Power ◽  
Short Period ◽  
Startup Process ◽  
Startup Period ◽  
Transient Operations

The startup period, one of several transient operations in a centrifugal pump, takes note of some problems with these devices. Sometimes a transient high pressure and high flow rate over a very short period of time are required at the startup process. The pump’s dynamic response is delayed because of the rotational inertia of the pump and motor. Our research focuses on how to get a large flow in a short time when the pump cannot meet the requirements alone without a large power driver. To achieve a strong response in the startup process, a ball valve is installed downstream of the pump. The pump’s transient behavior during such transient operations is important and requires investigation. In this study, the external transient hydrodynamic performance and the internal flow of the pump during the transient startup period are studied by experiments and simulations. In order to find an appropriate matching method, different experiments were designed. The content and results of this paper are meaningful for performance prediction during the transient pump-valve startup period.

Study on the Transient Characteristics of Pump During the Starting Process With Assisted Valve

2017 ◽  
Author(s):  
Qiao Li ◽  
Peng Wu ◽  
Dazhuan Wu
Keyword(s):  
Transient Process ◽  
Rotational Speed ◽  
Internal Flow ◽  
Transient Behavior ◽  
Hydrodynamic Performance ◽  
Rotational Inertia ◽  
Startup Process ◽  
Starting Process ◽  
Short Time ◽  
Transient Operations

Among the various transient operations, the startup process of a centrifugal pump brings attention to a number of practical issues. A representative application of the startup process is the underwater launch, which requires transient high pressure and high flowrate during a very short time. Due to the rotational inertia of the pump and motor, the dynamic response of the pump is slow, so the rotational speed cannot reach the design point rapidly. To get a high response of the starting process, a throttle valve is installed in the downstream of the pump. The valve keeps closed before the rotational speed of the pump reaches a certain point. It is important to investigate the transient behavior of pump during such transient operations. In this paper, experiment and numerical simulation are implemented to study the external transient hydrodynamic performance and the internal flow of the pump during the transient process. Different operating schemes of the pump and valve are designed to find the best coordinated modes. The contents and conclusions of the current work can provide references for the performance prediction, design optimization and fluid control of the pump and valve during the transient process.

scholarly journals Transient Characteristics of Water-Jet Propulsion with a Screw Mixed Pump during the Startup Process

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Wei Han ◽  
Teng Zhang ◽  
You Liang Su ◽  
Ran Chen ◽  
Yan Qiang ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Water Jet ◽  
Quadratic Functions ◽  
Hydrodynamic Characteristics ◽  
Jet Propulsion ◽  
Short Period ◽  
Shaft Power ◽  
Startup Process ◽  
Startup Period ◽  
Thrust And Torque

In order to investigate the transient hydrodynamic characteristics of water-jet propulsion with a screw mixed pump during the startup period and to overcome the difficulties in measuring the transient process parameters over a very short period of time, a method based on a flume experiment combined with computational fluid dynamics (CFD) is proposed. The thrust and torque of the pump-jet propulsion according to mooring status at different rotational speeds were measured by the test, which provided a group of data for the boundary and initial conditions of the numerical calculation of the user-defined function (UDF). Consecutive changes in the parameters of the water-jet propulsion dynamics can be captured from the numerical simulation of the startup process with the UDF. Thus, the transient hydrodynamic characteristics of water-jet propulsion according to time or rotation speed were obtained. The results show that the relationship between the thrust or torque of the water-jet propeller and pump rotational speed is close to the quadratic functions. The energy characteristic parameters of screw mixed water-jet pump, such as the flow rate, head, shaft power, and efficiency, rapidly increase and decrease and then remain relatively stable.

Study of Transient Behavior in Centrifugal Pump During Startup Period

2012 ◽  
Author(s):  
Yu-liang Zhang ◽  
Zu-chao Zhu ◽  
Bao-ling Cui ◽  
Yi Li
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Transient Flow ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Pipe System ◽  
Rotor Stator Interaction ◽  
Startup Period

To explore the transient characteristic of a centrifugal pump with the specific speed of 90 during startup period, the internal three-dimensional unsteady flow was solved by using CFD. Wherein to overcome the difficulty in implement of boundary conditions in numerical simulation, a closed-loop pipe system that includes a centrifugal pump was built to accomplish self-coupling calculation. The results show that at the very beginning of startup, flow rate rises slowly and non-dimensional head coefficient is much higher than quasi-steady value, the quasi-assumption can not be competent for predicting transient effect well. Moreover, the insufficient of energy conversion makes the evolvement of transient flow field lags behind that of quasi-steady flow field, i.e., kinetic energy can’t convert pressure energy in time during acceleration flow period. Rotor-stator interaction makes flow rate present slight fluctuation characteristic under stable operating conditions.

Performance characteristics of the new Eurosets magnetically suspended centrifugal pump

Perfusion ◽  
2020 ◽  
pp. 026765912093199
Author(s):  
Denis Berdajs ◽  
Ludwig K von Segesser ◽  
Francesco Maisano ◽  
Guiseppina Milano ◽  
Enrico Ferrari
Keyword(s):  
Centrifugal Pump ◽  
Repeated Measurements ◽  
Hydrodynamic Performance ◽  
Membrane Oxygenator ◽  
Mean Flow ◽  
Biochemical Tests ◽  
Extracorporeal Membrane Oxygenator ◽  
Pump Head ◽  
Ventricular Assistance Device ◽  
Magnetically Suspended Centrifugal Pump

Objective: The aim was to evaluate the performance of a newly developed magnetically suspended centrifugal pump head intended for use as a ventricular assistance device with a newly developed extracorporeal membrane oxygenator setup. Methods: In an experimental setup, an extracorporeal membrane oxygenator circuit was established in three calves with a mean weight of 68.2 ± 2.0 kg. A magnetically levitated centrifugal pump was tested, along with a newly designed extracorporeal membrane oxygenator console, at three different flow ranges: (a) 0.0 to 5.2 L/min, (b) 0.0 to 7.1 L/min, and (c) 0.0 to 6.0 L/min. For each setup, the animals were supported by a circuit for 6 h. Blood samples were collected just before caridiopulmonary bypass (CPB) after 10 min on bypass and after 1, 2, 5, and 6 h of perfusion for hemolysis determination and biochemical tests. Values were recorded for blood pressure, mean flow, and pump rotational speed. Analysis of variance was used for repeated measurements. Results: Mean pump flows achieved during the three 6 h pump runs for the three pump heads studied were as follows: (a) flow range 0.0 to 5.2 L/min, 3.6 ± 1.5 L/min, (b) flow range 0.0 to 7.1 L/min, 4.9 ± 1.3 L/min, and (c) flow range 0.0 to 6.0 L/min, 3.8 ± 1.5 L/min. Blood trauma, evaluated by plasma hemoglobin and lactate dehydrogenase levels, did not help in detecting any significant hemolysis. Thrombocytes and white blood cell count profiles showed no significant differences between the groups at the end of the 6 h perfusion. At the end of testing, no clot deposition was found in the oxygenator, and there was no evidence of peripheral emboli. Conclusion: The results suggest that the newly developed magnetically suspended centrifugal pump head provides satisfactory hydrodynamic performance in an acute perfusion scenario without increasing hemolysis.

Experimental and Theoretical Study of a Prototype Centrifugal Pump during Startup Period

2013 ◽  
Vol 30 (2) ◽  
Author(s):  
Yu-Liang Zhang ◽  
Zu-Chao Zhu ◽  
Hua-Shu Dou ◽  
Bao-Ling Cui ◽  
Yi Li
Keyword(s):  
Centrifugal Pump ◽  
Theoretical Study ◽  
Startup Period

Numerical Simulation of the Transient Flow in a Centrifugal Pump during Regulating Period

2011 ◽  
Vol 268-270 ◽  
pp. 1407-1410
Author(s):  
Yue Tang ◽  
Er Hui Liu ◽  
Ling Di Tang ◽  
Wang Hui
Keyword(s):  
Fluid Flow ◽  
Centrifugal Pump ◽  
Moving Boundary ◽  
Transient Flow ◽  
Pressure Fluctuations ◽  
Angular Acceleration ◽  
Internal Flow ◽  
Dynamic Mesh ◽  
Hydrodynamic Performance ◽  
State Process

Centrifugal pump performance has transient effect obviously during rapid changing period and the pump hydrodynamic performance of transient is different from steady-state process. In order to research the speed regulation characteristics and the inner flow mechanism of the centrifugal pump, numerical method of solving the unsteady fluid flow around the accelerating blade was established. The dynamical changes of the pressure and velocity were simulated by Fluent6.2, using standard k-epsilon turbulence model, PISO algorithm. The dynamic mesh technology and UDF were used to deal with the moving boundary caused by changing speed. Simulation results shown that faster angular acceleration made larger pressure fluctuations. Different regulated time had different influence in the system transient characteristics. And the evolution of the internal flow rate present strong transient performance in the regulating process. The study confirmed the feasibility of dynamic mesh method in solving the transient fluid flow during pump regulating period.

scholarly journals X-Ray Measurements in a Cavitating Centrifugal Pump During Fast Start-Ups

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
S. Duplaa ◽  
O. Coutier-Delgosha ◽  
A. Dazin ◽  
G. Bois
Keyword(s):  
Centrifugal Pump ◽  
Rocket Engine ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
X Ray ◽  
Speed Increase ◽  
Start Up ◽  
Fast Start ◽  
Start Ups

The start-up of rocket engine turbopumps is generally performed in a few seconds or even less. It implies that these pumps reach their nominal operating conditions after a few rotations only. During the start-up, the flow evolution within the pump is governed by transient phenomena, based mainly on the flow rate and rotation speed increase. Significant pressure fluctuations, which may result in the development of cavitation, are observed. A centrifugal impeller whose transient behavior during start-ups has been detailed in a previous publication is considered. Three different cases of fast start-ups have been identified according the final operating point (Duplaa et al., 2010, “Experimental Study of a Cavitating Centrifugal Pump During Fast Start-Ups,” ASME J. Fluids Eng., 132(2), p. 021301). The aim of this paper is to analyze the evolution during the start-ups of the local amount of vapor in the blade to blade channels of the pump by fast X-ray imaging. This technique has enabled to calculate the time-evolution of the fluid density within the pump, which appears to be correlated with pressure time-evolutions. For each investigated start-up, X-ray measurements have been performed at three different sections of the impeller height. For each investigated start-up and section tested, measurements have been performed for several initial positions of the impeller, to estimate the measurement uncertainty, and to obtain records from different beam angles, like in tomography.

Simulation of the Early Startup Period of High-Temperature Heat Pipes From the Frozen State by a Rarefied Vapor Self-Diffusion Model

1993 ◽  
Vol 115 (1) ◽  
pp. 239-246 ◽  
Author(s):  
Y. Cao ◽  
A. Faghri
Keyword(s):  
Heat Pipe ◽  
Diffusion Model ◽  
Numerical Results ◽  
Vapor Flow ◽  
Pipe Length ◽  
Self Diffusion ◽  
Temperature Heat ◽  
Startup Process ◽  
Startup Period ◽  
Good Agreement

The heat pipe startup process is described physically and is divided into five periods for convenience of analysis. The literature survey revealed that none of the previous attempts to simulate the heat pipe startup process numerically were successful, since the rarefied vapor flow in the heat pipe was not considered. Therefore, a rarefied vapor self-diffusion model is proposed, and the early startup periods, in which the rarefied vapor flow is dominant within the heat pipe, are first simulated numerically. The numerical results show that large vapor density gradients existed along the heat pipe length, and the vapor flow reaches supersonic velocities when the density is extremely low. The numerical results are compared with the experimental data of the early startup period with good agreement.

scholarly journals Experimental Study of a Cavitating Centrifugal Pump During Fast Startups

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
S. Duplaa ◽  
O. Coutier-Delgosha ◽  
A. Dazin ◽  
O. Roussette ◽  
G. Bois ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Transient Flow ◽  
Flow Behavior ◽  
Rocket Engine ◽  
Rotation Velocity ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Physical Analysis ◽  
Different Types

The startup of rocket engine turbopumps is generally performed only in a few seconds. It implies that these pumps reach their nominal operating conditions after only a few rotations. During these first rotations of the blades, the flow evolution in the pump is governed by transient phenomena, based mainly on the flow rate and rotation speed evolution. These phenomena progressively become negligible when the steady behavior is reached. The pump transient behavior induces significant pressure fluctuations, which may result in partial flow vaporization, i.e., cavitation. An existing experimental test rig has been updated in the LML Laboratory (Lille, France) for the startups of a centrifugal pump. The study focuses on the cavitation induced during the pump startup. Instantaneous measurement of torque, flow rate, inlet and outlet unsteady pressures, and pump rotation velocity enable to characterize the pump behavior during rapid starting periods. Three different types of fast startup behaviors have been identified. According to the final operating point, the startup is characterized either by a single drop of the delivery static pressure, by several low-frequency drops, or by a water hammer phenomenon that can be observed in both the inlet and outlet of the pump. A physical analysis is proposed to explain these three different types of transient flow behavior.

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