Study of a Novel Air-augmented Waterjet Boost Concept

2014 ◽  
Vol 30 (01) ◽  
pp. 1-6 ◽  
Author(s):  
Alon Gany ◽  
Aviad Gofer
Keyword(s):  
Kinetic Energy ◽  
Airflow Rate ◽  
Water Tank ◽  
Static Tests ◽  
Pump Operation ◽  
Marine Propulsion ◽  
Analysis Experiment ◽  
Exhaust Jet ◽  
Propulsion Concept ◽  
Engine Power

This research presents analysis, experiment, and prediction of the performance of a unique marine propulsion concept, the air-augmented waterjet, having a revolutionary potential for significant thrust augmentation and boost capability of waterjet systems. So far, this concept has not been realized in any operational vessel. The air-augmented waterjet propulsion concept is similar to an after-burner in the aeronautical turbojet engine. The thrust augmentation results from the injection of air bubbles into the water flow, converting their expansion work òpdV into additional kinetic energy of the exhaust jet without affecting the pump operation. It can enable substantially augmenting boost capability, overcoming hump resistance, and increasing maximum attainable vessel speed while avoiding cavitation problems. Static tests at the Technion's water tank, using a jetski waterjet engine of a nominal power of 50 kW, have been conducted with and without air injection over a range of motor revolutions per minute (rpm). The addition of air increased the thrust by 20% to 50% depending on the airflow rate and engine rpm. Air expansion work increased the exhaust jet kinetic energy at an efficiency of 70% approximately. Based on the static experiments, prediction of the system behavior for different vessel speeds and engine power levels has been made, revealing a higher relative thrust augmentation for the same pump power and airflow rate at higher vessel speeds. The air-augmented waterjet concept may add a new dimension to marine propulsion as well as upgrade existing vessels.

A Low Noise Propulsion Concept for the Supersonic Transport

1991 ◽  
Author(s):  
G. A. Champagne ◽  
G. E. Allen ◽  
M. Palmieri ◽  
R. M. Adler
Keyword(s):  
High Speed ◽  
Thermal Noise ◽  
Noise Suppression ◽  
Low Noise ◽  
Environmental Standards ◽  
Supersonic Transport ◽  
Engine Design ◽  
Exhaust Jet ◽  
Propulsion Concept ◽  
Jet Velocities

The major challenges with the design of propulsion systems for High speed Civil Transports (HSCT) are complying with FAR and EPA environmental standards while powering an economically acceptable aircraft. These issues create a dilemma in engine design because low exhaust jet velocities are required to meet takeoff noise regulations while high exhaust jet velocities are required for economical supersonic cruise operation. Previous studies have shown that to meet FAR Stage 3 noise regulations, engines incorporating mechanical/thermal noise suppression concepts must be oversized by 50 to 80% relative to the size that will provide the maximum aircraft economics. In order to achieve the Stage 3 noise levels without oversizing the engine, the engine airflow must be increased by 120% during takeoff operation to reduce the average exhaust velocity to an acceptable level. This paper will examine a concept that brings in 74% additional airflow into the engine’s inlet and 46% into the engine’s exhaust nozzle. The impacts of this concept on engine design, performance, size and weight and on aircraft takeoff gross weight (TOGW) and range are evaluated. For the same TOGW aircraft, this noise reduction concept provides a 70% range improvement relative to engines which incorporate mechanical/thermal noise suppressors. This concept was developed under a NASA sponsored program.

scholarly journals Performance and Feasibility Study of a Novel Automated Catch-Hauling Device Using a Flexible Hose Net Structure in Set-Net

2021 ◽  
Vol 9 (9) ◽  
pp. 1015
Author(s):  
Qiao Li ◽  
Yue Li ◽  
Shuchuang Dong ◽  
Yoichi Mizukami ◽  
Jialin Han ◽  
...  
Keyword(s):  
Feasibility Study ◽  
Buoyancy Force ◽  
Airflow Rate ◽  
Water Tank ◽  
Flexible Hose ◽  
Opposite Edge ◽  
Lower Efficiency ◽  
Live Fish ◽  
Lower Productivity ◽  
Motion Parameters

The labor-intensive catch-hauling method in set-net fisheries faces problems of lower productivity, lower efficiency, and higher operational risk due to aging problem and labor insufficiency. To solve such problems, a novel catch-hauling device using the flexible fire hose and net (hose net), which is placed in the box chamber, was proposed in this study. The hoses were inflated with air injected into one edge of the hose net, and the buoyancy force increased: the net gradually floated up, cornering the fish in the opposite edge. To corner and harvest the fish efficiently and safely, the changing formation and motion parameters of the hose net are significant. A series of floating up, sinking experiments, and catch-hauling tests were conducted to evaluate the performance of this device. The results showed that the hose net could gradually float in an ideal form and sink smoothly through natural exhaust and stretched on the bottom of the water tank. The time spent and average speeds in floating and sinking processes varied with air pressure and airflow rate, allowing the hose net motion to be controlled in practice by adjusting the airflow. Through the catch-hauling test using live fish, most of the fish were directed into the fish bag. Two main capture failure phenomena were also observed. Overall, this newly developed automated catch-hauling device is expected to be successful for use in modern fisheries.

scholarly journals Near-Field Measurements of Water-Entry Sound of Low-Speed Metal Balls in a Non-Anechoic Tank

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Qi Li ◽  
Yihan Yang ◽  
Dajing Shang ◽  
Rui Tang ◽  
Fangzhou Deng
Keyword(s):  
Kinetic Energy ◽  
Time Domain ◽  
Power Level ◽  
Near Field ◽  
Average Power ◽  
Water Entry ◽  
Transient Signal ◽  
Water Tank ◽  
Ball Size ◽  
The Impact

As one of the target characteristics, water-entry sound characteristics are of great significance to study, and its research has certain reference value for the detection of sea target. The water-entry sound of an underwater target is a transient sound signal, and it is mainly measured in open water such as the sea and lakes. However, due to the short duration of the acoustic signal and the modulation effect of the measuring environment, it is difficult to measure water-entry sound. To deal with this problem, in this work, the water-entry sound of a metal ball was measured in a water tank in a laboratory. The measurements were made in the direct acoustic control area 0.45 m away from the drop point of the ball to eliminate the influence of reflection. Through a time-domain integration, the power of the transient signal of the water-entry sound of the metal ball was obtained. The energy of the initial impact sound and the pulsating-bubble sound was investigated, as was the impact of ball size, entry velocity, and other factors on the characteristics of the water-entry sound. The results show that by combining the virtual-source method with the time-domain integral in the near field, the energy of the incoming sound can be obtained accurately. The results are consistent with closed-space measurements. The water-entry sound includes the initial impact sound and the pulsating-bubble sound. The energy of the pulsating-bubble sound is 3–5 orders of magnitude larger than that of the initial impact sound. The average power level of the water-entry sound is proportional to the ball size and the 2/3 power of the slamming velocity. The relation between the average power level and the 1/3 power of the kinetic energy is an exponential function with base 10. Based on the kinetic energy variety of metal balls entering the water, an acoustic model of this system is established. The results can be used for reference to other transient sound measurements.

An Improved Method for Evaluating the Moisture Diffusivity in a Membrane

2010 ◽  
Vol 297-301 ◽  
pp. 682-687 ◽  
Author(s):  
T. Hu ◽  
J.C. Min ◽  
Y.Z. Song
Keyword(s):  
Test Section ◽  
Present Method ◽  
Sandwich Structure ◽  
Simple Structure ◽  
Moisture Diffusivity ◽  
Moisture Resistance ◽  
Airflow Rate ◽  
Water Tank ◽  
Improved Method ◽  
Set Up

A method that combines the experimental measurements and numerical simulations to determine the moisture diffusivity in a membrane has been developed. An experimental set-up was designed and constructed to measure the total moisture resistance. The test section consists of an airflow channel, a membrane, and a water tank, which form a sandwich structure. The process of moisture transport from the water surface to the airstream in the channel is numerically simulated to obtain the variation of the total moisture resistance with the moisture diffusivity in the membrane, which is then determined by comparing the experimental and numerical total moisture resistances. There are three features with the present method, i.e., simple structure of the test section, combination of the experiment and simulation, and consideration of the boundary layer resistances on both sides of the membrane. Tests were conducted on two PVDF membranes with 0.22 and 0.45 μm mean pore diameters. The results show that the moisture diffusivities in both membranes are in the order of 10-6 kgm-1s-1, with a larger pore size tending to yield a larger diffusivity. The moisture diffusivities in both membranes are insensitive to the airflow rate.

Research on Optimal Operation of Raw Water Pumping System Based on Hydromechanics in Waterworks

2013 ◽  
Vol 327 ◽  
pp. 294-300
Author(s):  
Shi Feng Huang ◽  
Feng Wang ◽  
Hui Xu ◽  
Xiao Xian Wei
Keyword(s):  
Mathematical Models ◽  
Simulation Models ◽  
Optimal Operation ◽  
Water Tank ◽  
Raw Water ◽  
Initial Water ◽  
Pump Operation ◽  
Pumping System ◽  
Water Pumping ◽  
Pump Station

According to the raw water pumping system with constant speed pump and variable speed pumps based on hydromechanics in waterworks, the hydraulic simulation models were built including pump station, water tanks, suction well etc. Based on the analysis of objective function and constraints of water treatment structures and consideration of pump operation and initial water level of clean-water-tank, the compact optimal operation mathematical models were built. Finally, correctness and advantage of the mathematical models were proved by the optimal simulation of Jinshan water supply project, which provided the valuable reference for the energy-saving operation of raw water pumping system.

Dynamics of a Marine Propulsion System With a Diesel Engine and a Propeller Subject To Waves

2015 ◽  
Author(s):  
Bhushan Taskar ◽  
Kevin Koosup Yum ◽  
Eilif Pedersen ◽  
Sverre Steen
Keyword(s):  
Diesel Engine ◽  
Fuel Efficiency ◽  
Propulsion System ◽  
Factors Affecting ◽  
Propulsion Performance ◽  
Marine Propulsion ◽  
Important Interaction ◽  
Ship Operation ◽  
Marine Propulsion System ◽  
Engine Power

When travelling in waves, the efficiency of the propulsion system is in most cases reduced, due to a variety of different effects. Traditionally, the performance of propeller and engine is analyzed separately. However, there might be important interaction effects, which this paper attempts to explore. Engine and propeller models have been coupled to obtain realistic response of the propulsion machinery and to observe the effect of interaction between engine and propeller. Experimental wake data have been used in the simulations. The effects of different factors affecting ship propulsion in waves have been noted and their effects have been calculated separately to analyze the influence of each of the factors on ship operation. A ship travelling in three different wavelengths of three different waveheights has been simulated. Influence of these waves on engine power and fuel efficiency has been studied. This paper is a step towards optimization of installed power through better prediction of sea margin with improved insights into the propulsion performance in waves.

The turbulent kinetic energy budget in a bubble plume

2019 ◽  
Vol 865 ◽  
pp. 993-1041 ◽  
Author(s):  
Chris C. K. Lai ◽  
Scott A. Socolofsky
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Liquid Velocity ◽  
Temporal Frequency ◽  
Asymptotic State ◽  
Air Bubbles ◽  
Water Tank ◽  
Bubble Plume ◽  
Air Void ◽  
Work Done

We present the turbulent kinetic energy (t.k.e.) budget of a dilute bubble plume in its asymptotic state. The budget is derived from an experimental dataset of bubble plumes formed inside an unstratified water tank. The experiments cover both the adjustment phase and asymptotic state of the plume. The diameters $d$ of air bubbles are in the range 1–4 mm and the air void fraction $\unicode[STIX]{x1D6FC}_{g}$ is between 0.7 % and 1.8 %. We measured the three components of the instantaneous liquid velocity vector with a profiling acoustic Doppler velocimeter. From the experiments, we found the following inside the heterogeneous bubble core of the plume: (i) the probability density functions of the standardized liquid fluctuations are very similar to those of homogeneous bubble swarms rising with and without background liquid turbulence; (ii) the characteristic temporal frequency $f_{cwi}$ at which bubbles inject t.k.e. into the liquid agrees with the prediction $f_{cwi}=0.14u_{s}/d$ observed and theoretically derived for homogeneous bubble swarms ($u_{s}$ is the bubble slip velocity); (iii) the liquid turbulence is anisotropic with the ratio of turbulence intensities between the vertical and horizontal components in the range 1.9–2.1; (iv) the t.k.e. production by air bubbles is much larger than that by liquid mean shear; and (v) an increasing fraction of the available work done by bubbles is deposited into liquid turbulence as one moves away from the plume centreline. Together with the existing knowledge of homogeneous bubble swarms, our results of the heterogeneous bubble plume support the view that millimetre-sized bubbles create specific patterns of liquid fluctuations that are insensitive to flow conditions and can therefore be possibly modelled by a universal form.

scholarly journals Smart Pump Operation Monitoring And Notification (PuMa) Via Telegram Social Messaging Application

2017 ◽  
Vol 1 (3) ◽  
pp. 57
Author(s):  
Mohamad Hanif Md Saad ◽  
Rabiah Adawiyah Shahad ◽  
Mohamad Zaki Sarnon ◽  
Muhammad Faiz Mohd Shukri ◽  
Aini Hussain
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Shortage ◽  
Water Tank ◽  
Notification System ◽  
Pump Operation ◽  
Smart Pump ◽  
Pump House ◽  
Social Messaging

Water supply system contains hydraulic components to supply water. The pumps are an important part in water distribution system and need to be well maintained for most of the time. The failure of pump operating system will result in the water shortage inside water tank. This phenomenon might occur due to the tripped pump and power. This paper proposed a remote monitoring and notification system applied in the pump house with the used of Complex Event Processing tools. Whereas, the notification system that act as an output adapter uses a Telegram Social Messaging application. The study is about how fast the notification system between using SMS and Telegram as an output adapter in the pump operation.

Instrumenting and Acquiring Data for the WR21 Gas Turbine Development Programme

2001 ◽  
Author(s):  
Grant Bridgeman ◽  
Chai Uawithya ◽  
Côme Crance
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Development Programme ◽  
Endurance Running ◽  
Marine Propulsion ◽  
Test House ◽  
Aero Engines ◽  
Data Acquisition And Processing ◽  
Difference Test ◽  
Engine Power

The development of the WR-21 Intercooled / Recuperated gas turbine started in 1991 and is now well advanced, having successfully completed ten engine tests at the Admiralty Test House (ATH) DERA Pyestock, NSWC Philadelphia and now having commenced endurance running at DCN, Indret. The WR21 is the next generation of gas turbine prime mover, providing a significant annual fuel saving over the current marine propulsion gas turbines. Based on the RB211 family of commercial aero engines, the components are modified to incorporate an intercooler and recuperator into the simple cycle engine arrangement, improving the engine power and specific fuel consumption respectively. The paper briefly outlines the engine tests of the WR21 development programme, and describes the instrumentation, data acquisition and processing systems that have been developed by Rolls Royce and the three difference test facilities to meet the varying demands of such gas turbine testing. The paper discusses the high levels of instrumentation used, its reliability and accuracy, the DAS architecture and the methods used to handle and process the data.

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