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Research Papers: Multiphase Flows

Research on Two Phase Waterjet Nozzles

[+] Author and Article Information
S. Gowing

Carderock Division, Naval Surface Warfare Center, West Bethesda, MD 20817-5700scott.gowing@navy.mil

T. Mori

Technical Research and Development Institute, Ministry of Defense, Tokyo 162-8801, Japantymori@castle.ocn.ne.jp

S. Neely

Carderock Division, Naval Surface Warfare Center, West Bethesda, MD 20817-5700stephen.neely@navy.mil

J. Fluids Eng 132(12), 121302 (Dec 29, 2010) (9 pages) doi:10.1115/1.4002999 History: Received November 24, 2008; Revised November 03, 2010; Published December 29, 2010; Online December 29, 2010

Air-augmented waterjets derive their propulsion from compressed gas mixed directly into the main flow. The gas bubbles expand as the mixture passes through the pressure gradient of the convergent nozzle, and energy is imparted to the water from the air in a complex fashion. This experiment measures the exchange of air and water energy for three nozzles over a range of flowrates and void fractions using compressed air injected and mixed upstream of the nozzle entrance. Pressures and nozzle thrust are measured to examine flow changes. The results are compared with predictions from a one-dimensional bubbly flow model. The measured efficiencies are lower than or comparable to predicted values.

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Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 10

Measuring points and energy flux definitions

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Figure 11

Bubble flows at various void fractions

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Figure 12

Nozzle discharge at different void fractions

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Figure 13

(a) Nozzle 1 efficiency trends, (b) nozzle 2 efficiency trends, and (c) nozzle 3 efficiency trends

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Figure 14

Power input for single phase and two phase flows at similar thrust levels

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Figure 1

Ramjet concept with compressed air (from Muench and Garrett (1))

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Figure 2

Air augmented waterjet concept with compressed air (from Muench and Garrett (1))

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Figure 3

(a) Schematic of pipe system (nozzle pointed away from plane of paper) and (b) nozzle and flexible hose on pipe system

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Figure 4

(a) Multiple tube injector and (b) resultant flow, largely separated

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Figure 5

(a) Venturi injector and (b) resultant flow, better mixed

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Figure 6

Nozzle internal diameter profiles

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Figure 7

Nozzle mounting schematic and picture

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Figure 8

Change of load cell sensitivity with inlet hose pressure

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Figure 9

Ratio of measured thrust to momentum (uniform velocity) thrust, water only

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