WATER JET CONFERENCE - Waterjet Technology Association

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VISUALIZATION OF THE CENTRAL CORE OF HIGH-SPEED <strong>WATER</strong> <strong>JET</strong>S AN INFRARED TECHNIQUE Eugene B. Nebeker, Ph.D., and John B. Cramer Scientific Associates, Inc. Santa Monica, California ABSTRACT Valuable information about structure, coherency, etc. of a high-speed water jet can be obtained by examining the central core. This problem is complicated because aerodynamic drag on the jet shears off the exterior surfaces of the core to form a mist which surrounds the jet. The presence of this mist often prevents direct observation of the core because the mist absorbs or scatters the light needed to visualize the core. Many investigators have employed photographic methods to penetrate the surrounding mist for the purpose of observing the core. These earlier procedures did not produce photographs with sufficient contrast to allow the examination of fine details of the jet. An infrared photography technique is presented which was developed to improve direct examination of a jet core. The procedure is inexpensive, relatively convenient, and adaptable to use in the field. The method uses light absorption and exploits the fact that water absorbs light in the infrared region of the spectrum much better than in the visible. INTRODUCTION Valuable information about structure, coherency, etc. of a high-speed water jet can be obtained by visualizing the central core. This problem is complicated because aerodynamic drag on the jet shears off the exterior surfaces of the core to form a mist which surrounds the jet. The presence of this mist often prevents direct observation of the core because the mist absorbs or scatters the light needed to visualize the core. Many investigators have employed photographic methods to penetrate the surrounding mist for the purpose of observing the core (Brown). Unfortunately, this earlier work was not useful to us in our Percussive Jet development (Nebeker and Rodriguez, 1973, 1979) because we needed to visualize very minute details of the fluid mechanics of a bunching mechanism. This process was happening, for example, 20,000 times per second while the individual bunches were travelling at the bulk velocity of the jet at about 1000 feet/second. Therefore, some process was needed to more effectively penetrate the mist surrounding the core of a high-speed jet. The technique should be capable of stopping the motion of the jet so details can be examined. The procedure should be inexpensive, relatively convenient, and adaptable to use in the field. 90
APPROACH Most photographic techniques operate by measuring the scattering or absorption of light from a subject. In the case of water, scattering is enhanced by the presence of an uneven surface or the occurrence of droplets. Absorption seemed to be a more promising process because it increases with increasing density of the subject such as that associated with the core itself. The absorption spectrum of water (Fig. 1, Washburn, 1929) shows that water absorbs light in the infrared and ultraviolet regions of the spectrum very well. Visible light is absorbed quite poorly. For photographic purposes, the infrared region is often more convenient to use than the ultraviolet portion because photographic materials are more readily available and glass lenses, etc. do not absorb infrared light as easily as ultraviolet. Over 200 years ago, Lambert (1760),discovered that when a parallel beam of monochromatic light of wavelength X and intensity l o enters a homogeneous absorbing material, the light which is transmitted through a layer of thickness t will have the intensity I( ) = I o ( )e − k( ) l (1) where k is a positive constant called the absorption coefficient of the material. Lambert's law can be derived by assuming that each infinitesimally thin layer of the absorbing material absorbs an amount of light which is proportional to the thickness of the layer and to the intensity of the monochromatic radiation reaching it. This relation is shown schematically (Fig. 2) for a typical jet. Usually, strictly monochromatic light is not employed. However, equation 1 is also valid over a region of the spectrum when the absorption coefficient is a weak function of wavelength or in a reasonably small region of the spectrum for which the incident light is continuous (Nebeker, 1965). Problems sometimes arise if equation 1 is applied in regions where the absorption spectrum is discrete and not continuous. However, the experimental circumstances can often be adjusted so that this equation is an adequate representation of the observations. Differentiating equation 1 with respect to thickness t (k and I o are constants) dI dl k = e Io −kl (2) Hence, the rate of change of transmitted light intensity is proportional to the absorption coefficient k. Figure 1 shows that the absorption coefficient is two or three orders of magnitude greater in the infrared region of the spectrum than the visible. Therefore, equation 2 indicates that this infrared approach will yield results which are much more sensitive to variations in width and size of the central core of the jet than one would expect using light in the visible region of the spectrum. 91
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Proceedings of the Second U.S. WATE
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Visualization of the Central Core o
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A Status Report on the Conceptual D
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SESSION 7 - CIVIL & INDUSTRIAL Chai
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Cutting Hard Rock With Abrasive-Ent
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frictional and piping component rel
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R = a1 ⋅ A1 A2 a2 I = 2H o Q o
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attenuation of the output. The tran
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Figure 1. Branch System Modulator F
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Figure 5. Modulation Response for B
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Figure 9. Modulation response for s
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can be used for any form of input.
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with a cylindrical shape to the jet
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m/s. The range of power found from
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Figure 3. Power vs nozzle diameter
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Figure 5. Frequency vs length of th
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NAME: Gerald Zink COMPANY: StoneAge
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modulatornozzle assembly. The ordin
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DISCUSSION OF FLUID MECHANICS The i
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This process serves to protect the
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For test purposes, these concrete b
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REFERENCES CITED 1. Barker, C. R.,
Page 46 and 47: FIGURE 4. INNER CORE OF PERCUSSIVE
Page 48 and 49: FIGURE 9. EXAMPLE OF HIGH-PRESSURE
Page 50 and 51: NAME: John E. Wolgamott COMPANY: St
Page 52 and 53: THE FOCUSED SHOCK TECHNlQUE FORPROD
Page 54 and 55: The reflected wave is thus also cyl
Page 56 and 57: neglected. The introduction of a co
Page 58 and 59: DISCUSSION NAME: George Savanick CO
Page 60 and 61: H’ mean shape factor Hj theoretic
Page 62 and 63: Required streamline curvature at th
Page 64 and 65: 2 x 2 ≅ ( e − 2 p + w)/k2 (2-8)
Page 66 and 67: eliminating 2 n r 2 from equations
Page 68 and 69: approximation to the actual flow si
Page 70 and 71: skin friction coefficient but are c
Page 72 and 73: where: (H) = A1H 3 + A2H 2 + A3H +
Page 74 and 75: effect (< 0.5%) on coefficients of
Page 76 and 77: TABLE 5 Rei x 10 5 β 3 4 5 6 Po Po
Page 78 and 79: TABLE 6 D(mm) d o(mm) L t(mm) L f(m
Page 80 and 81: expanding rather than contracting a
Page 82 and 83: 25. Weber, H.E., 1978, Boundary lay
Page 84 and 85: Figure 5. Wall velocity distributio
Page 86 and 87: Figure 9. Effect of nozzle design o
Page 88 and 89: Figure 12. CA+T Design Philosophy.
Page 90 and 91: Figure 16. Effect of inlet b 1 cond
Page 92 and 93: Figure 20. Relaminarization at nozz
Page 94 and 95: Figure 24. Pressure decay data. 88
Page 98 and 99: DISCUSSION Although employing the i
Page 100 and 101: 5. Lambert, J. H., 1760, Photometri
Page 102 and 103: Figure 6. Spectral sensitivity curv
Page 104 and 105: NAME: W.C. Cooley COMPANY: Terraspa
Page 106 and 107: INTRODUCTION Pulsed liquid jets sho
Page 108 and 109: y=X ∨ P A dy = p p A p 2 (L c y=0
Page 110 and 111: Using equation (15), the value of X
Page 112 and 113: Thus about the first 10% of the dri
Page 114 and 115: Many design cases, including those
Page 116 and 117: surface spall occurred, resulting i
Page 118 and 119: Figure 3. Chamber pressure at pisto
Page 120 and 121: Figure 7. Effect of nozzle area rat
Page 122 and 123: Figure 11. Extrusion device schemat
Page 124 and 125: Figure 15. Typical chamber pressure
Page 126 and 127: DISCUSSION NAME: W. C. Cooley COMPA
Page 128 and 129: material which are, in turn, affect
Page 130 and 131: the water jet. This method was not
Page 132 and 133: where h is the depth of penetration
Page 134 and 135: obtained during this phase of the i
Page 136 and 137: observed that the smallest depth of
Page 138 and 139: Figure 2. Idealized Relationships b
Page 140 and 141: Figure 6. Penetration as a Function
Page 142 and 143: DEVELOPMENT OF VARIABLE DELIVERY TR
Page 144 and 145: THE STRUCTURE AND FUNCTION OF THE P
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The injection pressure can be contr
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ACKNOWLEDGEMENTS The authors gratef
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Figure 4. Theoretical required powe
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Figure 9. Variation of efficiency w
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THE "SKIPJACK" SEWER CLEANING NOZZL
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HYDRO-BLASTING SAFETY C.W. Adaway,
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Remember, your Hydro-Blasting work
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horizontal, sometimes vertical, and
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Figure 2. Safety Gear Figure 3. Tub
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DEVELOPMENTS IN CLEANING COKE OVEN
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causing chain breakages and the scr
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was encountered, then the rotation
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(C) Capital Expenditure: Material i
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Figure 9. Swivel coupling Figure 10
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OPTIMIZING JET CUTTING POWER FOR TU
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PRESSURE DROP (psi) ELEMENT Cv @10
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power output. Undersized nozzles re
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Subscripts n - Nozzle p - Pump t -
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Figure 1. Cutting effect as a funct
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CONSIDERATIONS IN THE COMPARISON OF
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pressure can be lowered to perhaps
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Figure 2: Fan jet issuing from a no
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DISCUSSION NAME: John Griffiths COM
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where Q = Flow rate - gpm D = Jet O
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Again, not limited to Newtonian flu
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REFERENCES 1. Brown, R.W. and Loper
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Table 2. Jet Cleaning Speeds and ot
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ANSWER: The utilization of the stat
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complexity and short component life
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Figure 4, for ap values ranging fro
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Decontamination Methods for rapidly
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a. “PULSER” b.”ORGAN-PIPE”
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Figure 5 - Removal rate for various
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DISCUSSION NAME: David A. Summers C
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DRILLING BORE HOLES IN COAL MINES U
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pile could not be judged as represe
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DISCUSSION NAME: David Summers COMP
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HYDRAULIC MINING EXPERIMENTS IN AN
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The monitor was fed pressurized wat
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The IH rig was considered to be sup
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REFERENCES 1. Okhrimenki, V. A., A.
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Figure 2. Jet cutting sandstone at
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Figure 5. Schematic plan view of In
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Figure 7. Suction Box. 226
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USE OF HIGH PRESSURE WATER JETS FOR
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flame torch to cut this block, redu
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the order of 360 rpm. Under these c
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Figure 3. Slot cut by jet at 11 o s
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JET-MINER SURFACE AND IN-SEAM TRIAL
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The hydraulic drive of the haulage
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The surface trials had have the obj
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Figure 2. Experimental version. Fig
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Figure. 7 Jet-Miner prototype Figur
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SOME PATTERNS OF TECHNOLOGY TRANSFE
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Development of High Pressure_Techno
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configurations, the design of an op
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and public sectors. After a haitus
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Souder, W.E. and Evans, R.J., "The
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Figure 5. Technological achievement
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Table 3. Perceived disadvantages of
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already been, or is being applied w
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Using the requirements profile and
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ant hose combination, a guiding sys
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HYDRAULIC MINING TESTS Site selecti
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SAFETY All operations were carried
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TABLE V. Categories of Jet Mining D
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Figure 2. Generalized geologic prof
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SECONDARY FRAGMENTATION WITH WATER
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do possess a maximum point (Fig. 8)
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Figure 4. Rossin-Rammler plot. Figu
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Figure 8. Non-dimensional plot for
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HYDRAULIC COAL MINING SYSTEM Typica
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Figure 4. (From ref. 1) DISCUSSION
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INTRODUCTION Developing an unique t
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The coefficients "b " in Eq. (1) ca
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By the end of 1982, a total of more
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Figure 4. Cutting ability of swing-
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Figure 10. An operating performance
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for an abrasive, the abrasive parti
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the particles, while at slower spee
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to break away the remaining segment
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Table 1. Concrete saw technology. T
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NAME: Tom Brunsing COMPANY: Foster-
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FEASIBILITY STUDY OF CUTTING SOME M
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hydraulic power required to cut thr
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pressure was varied from 103 to 310
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2.1 Heading and gutting fresh cod f
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Figure 5. The cuts surface of a blo
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Figure 17. Cuts made across the cla
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JET NOTCHING USED IN THE CONSTRUCTI
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Bottom notch diameter was determine
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σ H = in-situ stress in the horizo
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Figure 3. Final block displacement.
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Figure 8. Comparison of Slurry Pump
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THE FURTHER DEVELOPMENT OF AN UNDER
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use taps or hydrants. To achieve th
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supply line. It was determined that
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The rotating head requires major mo
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Figure 4. System field test set-up
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Figure 10. Bentonite drilled clay s
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MECHANICAL TOOLS Cutting Tool Energ
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Ψ = cos −1 ⎧ ⎪ ⎪ ⎨ ⎪
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mode also contributes to chip flush
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NAME: Simon Johnson COMPANY: Newcas
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ROLLER TOOLS COMBINED WITH HIGH-PRE
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Various designs and applications ar
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Figure 1. Full-face tunneling machi
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Figure 11. roadway profile cutting
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Figure 19. High-pressure water jet
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DESIGN AND OPERATION OF TWO LARGE-S
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The hydraulic system for the thrust
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Results of Trial Tests As part of m
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cutting rates, degree of bit wear,
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Overall approximate Weight: Basic M
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Figure 5. 3 ft. diameter laboratory
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nozzle diameter and cutting speed w
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2. Cutting Speed The influence of c
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energy it effects an increase in me
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Tip angle (degrees) 87 Off-set angl
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Figure 5. Figure 6. Figure 7 Figure
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Figure 17. Figure 18. Figure 19. Fi
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SCHEMES OF COAL MASSIF BREAKAGE BY
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out thoroughly an efficient scheme
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Research analysis has proved that t
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DEPENDENCE OF POWER INDICES OF COMB
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The experiments have shown how the
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K Ay = coefficient correcting for f
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Figure 1. Schemes of combined break
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Figure 5. Dependence of specific en
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Figure 12. Percentage of grade R -6
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Figure 1. Particle size analysis. T
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NAME: Dr. Henkel COMPANY: Bergbau-F
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presented. This study, of course, i
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identifying a general trend for the
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Effect of Abrasive Hardness, Shape
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In some situations, especially in c
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Figure 1. Abrasive waterjet nozzles
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Figure 8. Effect of standoff distan
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Figure 13. Abrasive waterjet cuts i
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CUTTING WITH ABRASIVE WATERJETS M.
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3.3 Abrasive Feed Systems For abras
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Because of the large number of infl
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due to wear. Although actual operat
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from this new technology. Table 2 l
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Table 1. materials cut by abrasive
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Figure 1. Abrasive waterjet nozzles
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a) kerfs in mild steel b) S.S. 15.5
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a) circle cutting in glass b) lamin
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DISCUSSION NAME: Andrew F. Conn COM
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CUTTING HARD ROCK WITH ABRASIVE-ENT
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slurry nozzle. Testing at water pre
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DISCUSSION OF TEST RESULTS Jet Conf
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materials. The flexibility in nozzl
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pressure can be wiped out if diffic
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9. Maurer, W.C., and Heilheckler, J
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Figure 5. Effect of abrasive feed r
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Figure 9. Accumulated depth of mult
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Figure 13. Close-up view of quartzi
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ABRASIVE INJECTION USAGE IN THE UNI
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sudden changes in the feed rate eff
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or the abrasive must be manually to
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clog; there not being sufficient ar
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CODE OF PRACTICE FOR THE USE OF ABR
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Figure 5. Water abrasive cleaning h
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Figure 15. 360 0 abrasive pipe clea
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ECONOMIC CONSIDERATIONS IN WATER JE
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Other criteria to be considered in
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3 MANUAL METHODS OF JET CLEANING &
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contractor with old, unsafe, equipm
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Figure 1. Showing the increased cos
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Figure 8. Automatic tube bundle cle
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ackground to the subsequent coopera
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The molecules of SUPER-WATER posses
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shaken just before use. SUPERWATER
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26. Bednarz, L.P., "Effects of Poly
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