High-speed IR thermography of submerged turbulent water jets

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

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Motion of Descending Solid Particles and Local Flow Around the Particles in Downward Turbulent Water Duct Flow (Keynote)

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-09021 ◽

2011 ◽

Author(s):

Yoshimichi Hagiwara ◽

Hideto Fujii ◽

Katsutoshi Sakurai ◽

Takashi Kuroda ◽

Atsuhide Kitagawa

Keyword(s):

Reynolds Number ◽

Time Scale ◽

High Speed ◽

Fluid Velocity ◽

Stokes Number ◽

Solid Particles ◽

Duct Flow ◽

Local Flow ◽

Particle Reynolds Number ◽

Turbulent Water

The Stokes number, the ratio of the particle time scale to flow time scale, is a promising quantity for estimating changes in statistics of turbulence due to particles. First, we explored the Stokes numbers in some recent studies. Secondly, we discussed the results of our direct numerical simulation for turbulent flow with a high-density particle in a vertical duct. In the discussion, we defined the particle Reynolds number from the mean fluid velocity in the near-particle region at any time. We evaluated a new local Stokes number for the particle. It is found that the Stokes number is effective for the prediction of the distance between the particle center and one wall. Finally, we carried out experiments for turbulent water flow with aluminum balls of 1 mm in diameter in a vertical channel. The motions of aluminum balls and tracer particles in the flow were captured with a high-speed video camera. We found that the experimental results for the time changes in the wall-normal distance of the ball and the particle Reynolds number for the ball are similar to the predicted results.

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Comparative study on interfacial oscillations of rectangular and elliptical liquid jets

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019900723 ◽

2020 ◽

Vol 234 (7) ◽

pp. 1272-1286 ◽

Cited By ~ 3

Author(s):

Amin Jaberi ◽

Mehran Tadjfar

Keyword(s):

Aspect Ratio ◽

Weber Number ◽

High Speed ◽

Nozzle Geometry ◽

Liquid Jets ◽

High Speed Photography ◽

Aspect Ratios ◽

Water Jets ◽

Switching Phenomenon ◽

Axis Switching

The instability characteristics and flow structures of water jets injected from rectangular and elliptical nozzles with aspect ratios varying from 2 to 6 were experimentally studied and compared. Shadowgraph technique was employed for flow visualization, and structures on the liquid jet surface were captured using high speed photography. It was found that disturbances originating from the nozzle geometry initially perturbed the liquid column, and then, at high jet velocities, disturbances generated within the flow dominated the jet surface. It was also found that rectangular nozzles introduced more disturbances into the flow than the elliptical ones. The characteristic parameters of axis-switching phenomenon including wavelength, frequency, and amplitude were measured and compared. Axis-switching wavelength was found to increase linearly with Weber number. Also, the wavelengths of rectangular jets were longer than the elliptical jets. Further, the frequency of axis-switching was shown to be reduced with increase of both Weber number and aspect ratio. It was observed that the axis-switching amplitude increased monotonically, reached a peak, and then decreased gradually. It was also found that the axis-switching amplitude varied with Weber number. At lower values of Weber number, the rectangular nozzles had higher amplitude than the elliptical nozzles. However, at higher values of Weber number, this relation was reversed, and the elliptical nozzles had the higher axis-switching amplitudes. This reversal Weber number decreased with the orifice aspect ratio. The reversal Weber number for aspect ratio of 4 was about 289, and it had decreased to 144 for the aspect ratio of 6.

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Non-Destructive Characterization of Railway Materials and Components with Infrared Thermography Technique

Materials ◽

10.3390/ma12244077 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4077 ◽

Cited By ~ 2

Author(s):

Jeongguk Kim

Keyword(s):

Infrared Thermography ◽

Thermal Imaging ◽

High Speed ◽

Hot Spot ◽

Imaging Techniques ◽

Brake Disc ◽

Ir Thermography ◽

Contact Mode ◽

Non Destructive Evaluation ◽

Non Destructive

Infrared (IR) thermography technology is one of the leading non-destructive evaluation (NDE) techniques based on infrared detection. Infrared thermography, in particular, has the advantage of not only being used in non-contact mode but also provides full images, real-time inspection, and relatively fast results. These advantages make it possible to perform thermal imaging analysis of railway materials and/or components, such as brake disc simulation, monitoring of abnormal heat generation, and monitoring of temperature changes, during mechanical tests. This study introduces the current state of research on railway materials and/or components using IR thermography technology. An attempt was made to characterize the deterioration of electrical equipment of diesel electric locomotives using infrared thermal imaging techniques. In addition, surface temperature monitoring was performed during tensile testing of railway steels using a high-speed infrared camera. Damage evolution due to the hot spot generation of railway brake discs was successfully monitored using high-speed IR cameras. In this paper, IR thermal imaging technology, used as a non-destructive evaluation analysis in the railway field, was introduced, and the results of recent research are presented.

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Development of Erosion in High-Speed Submerged Water Jets.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.60.736 ◽

1994 ◽

Vol 60 (571) ◽

pp. 736-743 ◽

Cited By ~ 8

Author(s):

Yoshiaki Yamauchi ◽

Hitoshi Soyama ◽

Kazunori Sato ◽

Toshiaki Ikohagi ◽

Risaburo Oba

Keyword(s):

High Speed ◽

Water Jets

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Scour by jets in cohesionless and cohesive soils

Canadian Journal of Civil Engineering ◽

10.1139/l07-005 ◽

2007 ◽

Vol 34 (6) ◽

pp. 744-751 ◽

Cited By ~ 14

Author(s):

Kerry A Mazurek ◽

Tanvir Hossain

Keyword(s):

Impinging Jets ◽

Coarse Grained ◽

Cohesive Soils ◽

Wall Jets ◽

Fine Grained ◽

Water Jets ◽

Turbulent Wall Jets ◽

Turbulent Wall ◽

Turbulent Water ◽

Unified Method

A technique is developed in this paper to unify the methods of analyzing scour by turbulent water jets in cohesionless and cohesive soils. Data from previous studies using circular turbulent impinging jets and circular turbulent wall jets are used to compare the scour in low void ratio cohesive soils to that in uniform sands and gravels. Scour by these jets is related to the dimensionless excess stress on the soil bed. It is seen that this parameter will likely work well for developing a method to predict scour for circular wall jets that is applicable to both materials. However, a circular impinging jet appears to vary appreciably in its interaction with the bed between the two types of soil, which makes developing a unified method to predict scour by impinging jets more difficult. Key words: erosion, scour, water jets, cohesionless sediments, cohesive sediments, fine-grained soils, coarse-grained soils.

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