This investigation is concerned with the possibility of augmenting the thrust of a conventional waterjet by utilizing the energy of an expanding gas to impart additional momentum to the water stream. The device under study is one in which compressed air is injected into the high-pressure water stream leaving the water pump. A mixture of water and finely dispersed air bubbles is generated in a constant-area mixing chamber, which joins the water-pump outlet. The two-phase bubbly mixture enters the exhaust nozzle and expands under the action of a negative pressure gradient. Internal thrust is analytically determined under the restrictions of certain simplifying assumptions. The mixing process is analyzed through the use of a control volume encompassing the entire mixing chamber. The two-phase nozzle flow is analyzed through application of the conservation laws for a single air bubble and an incremental control volume over a nozzle section. Results indicate that thrust augmentation is possible and most effective for low pump-outlet pressures and/or high mass flow ratios in the range permitting bubbly flow. Thrust augmentation is found to be only weakly dependent on air-injection temperature.

  • Corporate Authors:

    American Institute of Aeronautics and Astronautics

    1290 Avenue of the Americas
    New York, NY  United States  10019
  • Authors:
    • Amos, R G
    • Maples, G
    • Dyer, D F
  • Publication Date: 1973-4

Media Info

  • Features: References;
  • Pagination: p. 64-71
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00048427
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Nov 14 1973 12:00AM