Visual Observation and Analysis of Hydrodynamic Structure of Water Jet in Application to Jet Grouting

2007 ◽  
Author(s):  
Hiroshi Yoshida ◽  
Kennosuke Uemura ◽  
Kenji Yoshida ◽  
Isao Kataoka
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
Visual Observation ◽  
Water Jet ◽  
Structure Of Water ◽  
Jet Grouting ◽  
Hydrodynamic Structure ◽  
Jet Velocity ◽  
Very High

Water jet is utilized in various industrial application such as cutting carious materials and soil. In particular, jet grouting for soil improvement is one of the most important application of water jet under high pressure and high liquid flow rate. Such technology is already in practical use in civil engineering. In order to improve the efficiency and performance of jet grouting, it is quite important to clarify the hydrodynamic structure of water jet under high pressure and high flow rate. However, basic researches on this subject are quite insufficient both experimentally and analytically. Water jet utilized in jet grouting is usually very high speed ( up to 500 m/s) two-phase dispersed flow. Therefore, it is quite difficult to make visual observation of such water jet using conventional optical methods. In the present work, the authors utilized high sensitive CCD camera with image intensifier of which gate speed is 10 ns. Using this optical device, the authors obtained still image of high speed water jet for the first time. Visual observation revealed that high speed water jet is composed of very fine droplets and has complicated structures such as swirl and cluster of droplets. Velocity of water jet was also measured using two consecutive images taken between 10 microsecond. Such direct measurement of jet velocity of high speed water jet has not been carried out so far. The result indicated that jet speed (droplet speed) is even very high even at the boundary of water jet. Measure water jet velocity was reasonably correlated with jet velocity at the exit of nozzle.

scholarly journals The Design and Evaluation of a High Pressure Ratio Radial Turbine

1992 ◽  
Author(s):  
K. R. Pullen ◽  
N. C. Baines ◽  
S. H. Hill
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Performance Measurements ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Turbine Efficiency ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Very High

A single stage, high speed, high pressure ratio radial inflow turbine was designed for a single shaft gas turbine engine in the 200 kW power range. A model turbine has been tested in a cold rig facility with correct simulation of the important non-dimensional parameters. Performance measurements over a wide range of operation were made, together with extensive volute and exhaust traverses, so that gas velocities and incidence and deviation angles could be deduced. The turbine efficiency was lower than expected at all but the lowest speed. The rotor incidence and exit swirl angles, as obtained from the rig test data, were very similar to the design assumptions. However, evidence was found of a region of separation in the nozzle vane passages, presumably caused by a very high curvature in the endwall just upstream of the vane leading edges. The effects of such a separation are shown to be consistent with the observed performance.

Analysis of Static Characteristics of Pressure Seal in Actual High Pressure Pump

2011 ◽  
Author(s):  
Isao Hagiya ◽  
Katsutoshi Kobayashi ◽  
Yoshimasa Chiba ◽  
Tetsuya Yoshida ◽  
Akira Arai
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
Control Volume ◽  
Leakage Flow ◽  
High Pressure Pump ◽  
Flow Rates ◽  
Leakage Flow Rate ◽  
Rotor Dynamic ◽  
Pressure Seal

We predicted the leakage flow rates of a pressure seal in an actual high-pressure multistage pump. Since the pressure of the actual pump is higher than that of a model pump, accurate prediction of leakage flow rate and rotor dynamic forces for an actual pump is more difficult than that for a model pump. A non-contacting seal is used as a pressure seal to suppress leakage flow for high-pressure multistage pumps. When such pumps are operated at high speed, the fluid force acting on an eccentric rotor may cause vibration instability. For vibration stability analysis, we need to estimate static and dynamic characteristics of the pressure seals, i.e., leakage flow rate and rotor dynamic coefficients. We calculated the characteristics of the pressure seal based on Iwatsubo group’s method. The pressure seal we developed has labyrinth geometry consisting of grooves with different sizes. This method numerically calculates the characteristics of the grooved seal by using a three-control-volume model and a perturbation method. We compared the calculated and measured leakage flow rates. We found that the calculated results quantitatively agreed with the measured one in the actual pump and the characteristics of pressure and velocity for the seal with non-uniform-sized grooves were clarified.

scholarly journals Micro-channel milling using abrasive waterjets and high pressure abrasive slurry jets

2021 ◽  
Author(s):  
Naser Haghbin
Keyword(s):  
High Pressure ◽  
Particle Velocity ◽  
Flow Rate ◽  
Water Jet ◽  
Machining Process ◽  
Micro Milling ◽  
Micro Machining ◽  
Abrasive Water Jet ◽  
Micro Channels ◽  
Entrained Air

Abrasive water jet technology can be used for micro-milling using recently developed miniaturized nozzles. This thesis develops methodologies to predict the shape of micro-channels milled using high pressure abrasive water jets, and presents a new high pressure abrasive slurry jet micro-machining process. Since abrasive water jet (AWJ) machining is often used with both the nozzle tip and workpiece submerged in water to reduce noise and contain debris, the performance of submerged and unsubmerged abrasive water jet micro-milling of channels in 316L stainless steel and 6061-T6 aluminum at various nozzle angles and standoff distances were compared. It was found that the centerline erosion rate decreased with channel depth due to the spreading of the jet as the effective standoff distance increased, and because of the growing effect of the stagnation zone as the channel became deeper. The erosive jet spread over a larger effective footprint in air than in water, since particles on the jet periphery were slowed much more quickly in water due to increased drag. As a result, the width of a channel machined in air was wider than that in water. It was also found that the erosive efficacy distribution changed suddenly after the initial formation of the channel. Then, a new surface evolution model was developed that predicts the size and shape of relatively deep micro-channels up to aspect ratios of 3 resulting from unsubmerged and iv submerged abrasive water jet micro-machining (AWJM) using a novel approach in which two different erosive efficacy expressions were sequentially applied. Since the channels produced by AWJM were found to be relatively wavy due to fluctuations in abrasive mass flow rate, a novel high pressure (water pump pressure up to 345 MPa) abrasive jet slurry micro-machining (HASJM) system was introduced by feeding a premixed slurry into the mixing chamber of a water jet machine with a micro-nozzle. Moreover, an existing model developed for AWJM abrasive particle velocities was modified and used to predict the particle velocity in HASJM, and then verified using a double disc apparatus (DDA). The HASJM system was then used to study the effect of entrained air in abrasive water jet micro-machining (AWJM) by performing experiments at the same particle velocity and dose for the two systems. The centerline waviness, Wa, of micro-channels made in SS316L and Al60661-T6 using HASJM were typically 3.4 times lower than those made with AWJM using the same dose of particles due to the more constant abrasive flow rate provided by the HASJM provided. The centerline roughness, Ra was approximately the same in both processes at a traverse velocity of Vt=4572 mm/min and a nozzle angle of 90°. For micro-channels of a given depth, the widths of those made with HASJM were 25.6 % narrower than those produced with AWJM, mainly due to the wider jet that resulted from the entrained air in AWJM.

scholarly journals Micro-channel milling using abrasive waterjets and high pressure abrasive slurry jets

2021 ◽  
Author(s):  
Naser Haghbin
Keyword(s):  
High Pressure ◽  
Particle Velocity ◽  
Flow Rate ◽  
Water Jet ◽  
Machining Process ◽  
Micro Milling ◽  
Micro Machining ◽  
Abrasive Water Jet ◽  
Micro Channels ◽  
Entrained Air

Abrasive water jet technology can be used for micro-milling using recently developed miniaturized nozzles. This thesis develops methodologies to predict the shape of micro-channels milled using high pressure abrasive water jets, and presents a new high pressure abrasive slurry jet micro-machining process. Since abrasive water jet (AWJ) machining is often used with both the nozzle tip and workpiece submerged in water to reduce noise and contain debris, the performance of submerged and unsubmerged abrasive water jet micro-milling of channels in 316L stainless steel and 6061-T6 aluminum at various nozzle angles and standoff distances were compared. It was found that the centerline erosion rate decreased with channel depth due to the spreading of the jet as the effective standoff distance increased, and because of the growing effect of the stagnation zone as the channel became deeper. The erosive jet spread over a larger effective footprint in air than in water, since particles on the jet periphery were slowed much more quickly in water due to increased drag. As a result, the width of a channel machined in air was wider than that in water. It was also found that the erosive efficacy distribution changed suddenly after the initial formation of the channel. Then, a new surface evolution model was developed that predicts the size and shape of relatively deep micro-channels up to aspect ratios of 3 resulting from unsubmerged and iv submerged abrasive water jet micro-machining (AWJM) using a novel approach in which two different erosive efficacy expressions were sequentially applied. Since the channels produced by AWJM were found to be relatively wavy due to fluctuations in abrasive mass flow rate, a novel high pressure (water pump pressure up to 345 MPa) abrasive jet slurry micro-machining (HASJM) system was introduced by feeding a premixed slurry into the mixing chamber of a water jet machine with a micro-nozzle. Moreover, an existing model developed for AWJM abrasive particle velocities was modified and used to predict the particle velocity in HASJM, and then verified using a double disc apparatus (DDA). The HASJM system was then used to study the effect of entrained air in abrasive water jet micro-machining (AWJM) by performing experiments at the same particle velocity and dose for the two systems. The centerline waviness, Wa, of micro-channels made in SS316L and Al60661-T6 using HASJM were typically 3.4 times lower than those made with AWJM using the same dose of particles due to the more constant abrasive flow rate provided by the HASJM provided. The centerline roughness, Ra was approximately the same in both processes at a traverse velocity of Vt=4572 mm/min and a nozzle angle of 90°. For micro-channels of a given depth, the widths of those made with HASJM were 25.6 % narrower than those produced with AWJM, mainly due to the wider jet that resulted from the entrained air in AWJM.

scholarly journals Development of High-Efficiency, High-Speed and High-Pressure Ambient Temperature Filling System Using Pulse Volume Measurement

2019 ◽  
Vol 9 (12) ◽  
pp. 2491
Author(s):  
SeBu Oh ◽  
SeHoon Oh ◽  
ByeongRo Min
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
High Efficiency ◽  
Response Speed ◽  
Volume Measurement ◽  
Economic Feasibility ◽  
Industrial Sectors ◽  
Filling System ◽  
Filling Time

Adjusting the filling pressure is essential to fit the final gas volume when charging a carbonated beverage with high pressure. However, in the previous mechanical carbonated ambient filling system, it was difficult to control and monitor the charging conditions such as pressure, temperature and flow rate. In this study, we have developed a high efficiency carbonated ambient filling system capable of high speed and high pressure filling, by using a pulse type electronic flow-meter. The response speed characteristics of the M(BC) and F(MH) series valves were investigated. LMS Imagine.Lab Amesim (Siemens PLM Software) was used to calculate the charging and discharging time of the system under a high CO2 gas pressure condition. The quantitative and precise charging system was implemented with the change of filling time and monitoring/controlling/correction of flow rate. Moreover, a dual controller of the high-speed pulse output was established and a high-speed data processing/flow rate charging algorithm was applied in the system. The filling variation of the system was in the range of ±3 gram(gr) (standard deviation 0.57). The developed system could be applied to improve the quality of goods and economic feasibility at various industrial sectors.

scholarly journals Response of High-Pressure Micro Water Jets to Static and Dynamic Nonuniform Electric Fields

2018 ◽  
Vol 6 (2) ◽  
Author(s):  
Yi Shi ◽  
Jian Cao ◽  
Kornel F. Ehmann
Keyword(s):  
High Pressure ◽  
Electric Fields ◽  
High Speed ◽  
Water Jet ◽  
Dynamic Responses ◽  
Order System ◽  
Loop Control ◽  
Time Frequency ◽  
Water Jets ◽  
The Stability

The manipulation of the trajectory of high-pressure micro water jets has the potential to greatly improve the accuracy of water jet related manufacturing processes. An experimental study was conducted to understand the basic static and dynamic responses of high-pressure micro water jet systems in the presence of nonuniform electric fields. A single electrode was employed to create a nonuniform electric field to deflect a high-pressure micro water jet toward the electrode by the dielectrophoretic force generated. The water jet's motions were precisely recorded by a high-speed camera with a 20× magnification and the videos postprocessed by a LabVIEW image processing program to acquire the deflections. The experiments revealed the fundamental relationships between three experimental parameters, i.e., voltage, pressure, and the distance between the water jet and the electrode and the deflection of the water jet in both nonuniform static and dynamic electric fields. In the latter case, electric signals at different frequencies were employed to experimentally investigate the jet's dynamic response, such as response time, frequency, and the stability of the water jet's motion. A first-order system model was proposed to approximate the jet's response to dynamic input signals. The work can serve as the basis for the development of closed-loop control systems for manipulating the trajectory of high-pressure micro water jets.

Parameter study of Variation noise in outdoor of air conditioner

2021 ◽  
Vol 263 (4) ◽  
pp. 2822-2829
Author(s):  
Minkyu KIM ◽  
Byoungha Ahn ◽  
Simwon Chin
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
High Speed ◽  
Rapid Change ◽  
Volume Control ◽  
Parameter Study ◽  
Air Conditioner ◽  
Load Variations ◽  
Compressor Inlet ◽  
The Difference

In the outdoor unit of a room air conditioner, the main factors that made it possible to vary the ability of cooling and heating are the development of BLDC motors, advances in inverter technology, and the development of refrigerant volume control technology. The main reason for this change in cooling and heating capacity is that it is possible to change the RPS of compressors. As the range of the compressor's RPS expands, so does the range of response to load variations. This is mainly based on the capacity of the high-pressure refrigerant produced by the compressor. When the compressor rotates at high speed or low speed, the difference in noise occurs depending on the difference in rotational speed. Of course, fans and motors also contribute to noise fluctuations, but the overall governing factor is the greater contribution of refrigerant from compressors and compressors. The refrigerant flows into the cycle configured in the outdoor unit and varies in speed and flow rate depending on the amount of refrigerant. This results in vibration and noise appearing in the form of radiations, resonances, solid sounds, resonances, and so on. There are several factors that can cause vibration or noise changes depending on the flow velocity and flow rate. In this paper, we selected reactance of compressor motors, mufflers directly connected to compressor discharge ports and accumulator at compressor inlet where fluid vibrations occur the most. First of all, reactance of motor responds quickly to load fluctuations and has a large instantaneous torque to instantaneous load fluctuations. The muffler, which is directly connected to the compressor discharge port, is the first Cavity where high-pressure gas meets, and can evaluate the concentration of kinetic energy that generates noise and improve the collection center to reduce fluctuating noise. The Accumulator is the part with the lowest temperature of refrigerant gas entering the compressor, and the rapid change in the flow path causes the most fluid to generate vibration and radiation of the structure. For this reason, we select three elements first. In this paper, we specifically describe the background of selecting three elements of an air conditioning outdoor unit for the variability of noise over RPS changes. We demonstrate that these factors can review the feasibility of the experiment, explain the results of the analysis, and possibility of reduce the variation noise.

Numerical Simulation of High Speed Water Jet Erosion of Sand Bed Based on SPH

2014 ◽  
Vol 641-642 ◽  
pp. 304-308
Author(s):  
Fu Sheng Ni ◽  
De Yi Zhang ◽  
Hui Wang ◽  
Lei Gu
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Water Jet ◽  
Target Distance ◽  
Sph Method ◽  
Simulation Process ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Jet Velocity ◽  
Key Techniques

Water jet technology is widely used in dredging engineering. Since there will be large deformation of sand bed during erosion by water jet, the calculation mesh will be distorted seriously and lead to simulation failure. In order to solve the problem, the Smoothed Particle Hydrodynamics (SPH) method was used to simulate the dynamic process of high speed water jet erosion of sand bed. The simulation process and key techniques were discussed, the effect of water jet velocity and water jet target distance on the depth of eroded pit was studied. The results show that SPH could describe the process intuitively and the evolution of particle velocity field and sand bed pressure field could be shown clearly. The depth of the pit varies with time linearly. The decrease of water jet target distance and the increase of the water jet velocity deepen the eroded pit.

Image Analysis of Carry-Under by Falling Liquid Flow

2010 ◽  
Author(s):  
Tomohiko Ohtsuka ◽  
Naoki Haraguchi ◽  
Hiroyasu Ohtake ◽  
Yasuo Koizumi
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Flow Behavior ◽  
Wave Length ◽  
Video Camera ◽  
Water Jet ◽  
Water Pool ◽  
Nozzle Outlet ◽  
Pool Surface ◽  
High Speed Video Camera

Bubble carry-under into the water pool was examined. In experiments, a water jet from a nozzle of 5 mm in diameter plunged into the water pool. The distance between the nozzle outlet and the pool surface was 246 mm. Flow behavior in the water pool and also the state of the water jet surface were recorded with a high speed video camera. Following conclusions were obtained. When the flow rate of the water jet was small, the water jet disintegrated into small drops on the way from the nozzle outlet to the pool surface. The wave appearing position moved downward as the flow rate was increased. When the wave length reached the Kelvin-Helmholtz critical wave length, the water jet disintegrated into drops. When flow rate of the water jet was increased, the surface of the water jet became smooth and no perturbation was observed. The carry-under was not observed in this situation. When the flow rate of the water jet was further increased, large waves came to appear on the water jet surface. The wave appearing position moved upward as the flow rate was increased. Even if the wave length on the water jet reached the Kelvin-Helmholtz critical wave length, the water jet did not disintegrate into drops and the water jet plunges into the pool with large waves on the water jet. The penetration depth in this case was deep and the volume of the bubble carry-under was large compared with the case that the water jet disintegrated into drops.

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