THRUST OF AN AIR-AUGMENTED WATERJET WITH A CONVERGING- DIVERGING NOZZLE

This study is concerned with predicting the performance of an air-augmented waterjet with a converging-diverging nozzle. 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 coverging-diverging thrust nozzle and expands under the action of a negative pressure gradient. 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. Three different models which describe the heat transfer between the air bubbles and the water are considered. Results indicate that thrust augmentation is most effective for low pump-outlet pressures and for high mass flow ratios in the range permitting bubbly fow. The solution of the nozzle flow was accomplished by specifying the velocity distribution in the nozzle and calculating the nozzle geometry. Several expressions were used to calculate sonic velocity and it is shown that discrepancies exist between the computed results of the different expressions. Also none of the expressions place the sonic velocity at the throat. Thus, it is shown that further work is needed in determining sonic speed in two-phase compressible mixtures.

• Supplemental Notes:
  • Research was supported by the Office of Naval Research.
• Corporate Authors:

  American Institute of Aeronautics and Astronautics

  1290 Avenue of the Americas
  New York, NY  United States  10019
• Authors:
  • Maxwell, T T
  • Maples, G
  • Dyer, D F
• Publication Date: 1975-10

Media Info

• Features: References;
• Pagination: p. 154-159
• Serial:
  • Journal of Hydronautics
  • Volume: 9
  • Issue Number: 4
  • Publisher: American Institute of Aeronautics and Astronautics

Subject/Index Terms

• TRT Terms: Nozzles; Thrust; Two phase flow; Waterjet propelled craft
• Old TRIS Terms: Thrust augmentation; Waterjet propulsion
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00131083
• Record Type: Publication
• Source Agency: American Institute of Aeronautics and Astronautics
• Files: TRIS
• Created Date: Apr 21 1976 12:00AM