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

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.

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

Processes ◽

10.3390/pr8101241 ◽

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.

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Utilization of Open-Source OpenFOAM Code to Examine the Hydrodynamic Characteristics of a Linear Jet Propulsion System with or without Stator in Bollard Pull Condition

International Journal of Rotating Machinery ◽

10.1155/2020/8867416 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Parviz Ghadimi ◽

Negin Donyavizadeh ◽

Pouria Taghikhani

Keyword(s):

High Speed ◽

Water Jet ◽

Propulsion System ◽

Hydrodynamic Performance ◽

Hydrodynamic Characteristics ◽

Propulsion Systems ◽

Thrust Coefficient ◽

Jet Propulsion ◽

Marine Industry ◽

Total Thrust

With the development of high-speed crafts, new propulsion systems are introduced into the marine industry. One of the new propulsion systems is linear jet which is similar to pump jet and has a rotor, a stator, and a duct. The main difference between this system and pump jet is the placement of linear jet system under the hull body and inside a tunnel. Since this system, like a water jet, is inside the tunnel, the design idea of this system is a combination of a water jet and pump jet. In this paper, hydrodynamic performance of linear jet propulsion system is numerically investigated. To this end, the OpenFOAM software is utilized and RANS steady equations are solved using a k - ε turbulent model. The linear jet geometry is produced by assembling a Kaplan rotor, stator with a NACA 5505 cross section, and a decelerating duct. The results of numerical solution in the form of thrust, torque coefficient, and efficiency are compared with available experimental data for a ducted propeller, and good agreement is displayed. Subsequently, the hydrodynamic parameters are computed in two conditions: with a stator and without a stator. By comparing the results, it is observed that the total thrust coefficient of the propulsion system with a stator at all advance ratios increases by at least 40%. It is further observed that addition of a stator also improves its efficiency.

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Broken lines path following algorithm for a water-jet propulsion USV with disturbance uncertainties

Ocean Engineering ◽

10.1016/j.oceaneng.2020.107118 ◽

2020 ◽

Vol 201 ◽

pp. 107118 ◽

Cited By ~ 3

Author(s):

Yujiao Zhao ◽

Xin Qi ◽

Atilla Incecik ◽

Yong Ma ◽

Zhixiong Li

Keyword(s):

Path Following ◽

Water Jet ◽

Jet Propulsion ◽

Disturbance Uncertainties ◽

Path Following Algorithm

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Water-Jet Propulsion for High-Speed Hydrofoil Craft

Journal of Aircraft ◽

10.2514/3.59274 ◽

1966 ◽

Vol 3 (2) ◽

pp. 174-179 ◽

Cited By ~ 2

Author(s):

VIRGIL E. JOHNSON

Keyword(s):

High Speed ◽

Water Jet ◽

Jet Propulsion

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METHODOLOGIES TO PREDICT HYDRODYNAMIC CHARACTERISTICS OF PUSHER AND PULLER PODDED PROPULSORS IN OBLIQUE FLOWS

The International Journal of Maritime Engineering ◽

10.5750/ijme.v158ia4.1000 ◽

2021 ◽

Vol 158 (A4) ◽

Author(s):

M F Islam ◽

F Jahra

Keyword(s):

Computation Time ◽

Performance Characteristics ◽

Three Dimensions ◽

Hydrodynamic Characteristics ◽

Loading Conditions ◽

Time Step ◽

Podded Propulsor ◽

Multiple Loading ◽

Thrust And Torque ◽

Straight Ahead

This paper presents the outcome of a numerical simulation based research program to evaluate the propulsive characteristics of puller and pusher podded propulsors in a straight course and at static azimuthing conditions while operating in open water. Methodologies to predict the propeller thrust and torque, and pod forces and moments in three dimensions using a Reynolds-Averaged Navier Stokes (RANS) solver at multiple azimuthing conditions and pod configurations are presented. To obtain insight into the reliability and accuracy of the results, grid and time step dependency studies are conducted for a podded propulsor in straight-ahead condition. The simulation techniques and results are first validated against measurements of a bare propeller and a podded propulsor in straight ahead condition for multiple loading scenarios and in both puller and pusher configurations. Next, simulations were carried out to model the podded propulsors in the two configurations at multiple loading conditions and at various azimuthing angles from +30° to –30° in 15° increments. The majority of the simulations are carried out using both steady state and unsteady state conditions, primarily to evaluate the effect of setup conditions on the computation time and prediction accuracy. The predicted performance characteristics of the pod unit using the unsteady RANS method were within 1% to 5% of the corresponding experimental measurements for all the loading conditions, azimuthing angles and pod configurations studied. The non-linear behaviour of the performance coefficients of the pod unit are well captured at various loading and azimuthing conditions in the predicted results. This study demonstrates that the RANS solver, with proper meshing arrangement, boundary conditions and setup techniques can predict the performance characteristics of the podded propulsor in multiple azimuthing angles, pod configurations and in the various loading conditions with a same level of accuracy as experimental results. Additionally, the velocity and pressure distributions on and around the pod-strut- propeller bodies are discussed as derived from the RANS predictions.

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The Design of Water-Jet Propulsion Systems for Hydrofoil Craft

Marine Technology and SNAME News ◽

10.5957/mt1.1965.2.1.15 ◽

1965 ◽

Vol 2 (01) ◽

pp. 15-25

Author(s):

Joseph Levy

Keyword(s):

Water Jet ◽

Propulsion System ◽

Specific Design ◽

Propulsion Systems ◽

Propulsive Efficiency ◽

Jet Propulsion ◽

Performance Curves

This paper contains a brief description of the water-jet propulsion system as applied to hydrofoil craft, and a discussion of the salient hydrodynamic aspects of the problem of fitting the main propulsion system to the specified thrust-versus-speed requirements. The factors that affect the overall propulsive efficiency and the weight of the system are discussed at some length; procedures for optimization of performance at the design cruising speed are outlined; finally, the processes by which the performance at off-design conditions may be evaluated are discussed and illustrated with performance curves for one specific design.

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