Full Scale Evaluation of Waterjet Pump Impellers
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD SHIP PERFORMANCE DEPT
Pagination or Media Count:
Full scale experiments were conducted with a U. S. Navy waterjet- powered planing boat to evaluate three different waterjet impellernozzle configurations. The configurations consisted of the standard impellernozzle combination currently installed on these craft in addition to a newly designed impeller evaluated with two different diameter nozzles. The overall program objective was to determine if marine propeller design techniques can be applied to the design of waterjet impellers and thereby impeller efficiency. Results show that the waterjet with a newly designed impeller approached but did not meet or exceed the overall performance of the waterjet equipped with the standard impeller and nozzle. The inlet velocity measurements showed extreme local velocity variations in flow approaching the impeller suggesting that any improvement in the impeller would have a marginal improvement on overall performance of the waterjet. It is condluded that marine propeller design techniques cannot be practically applied to the design of waterjet impellers in the majority of waterjets where extremely high thrust disk loading conflicts with the moderately-loaded propeller theory upon which the design procedures are based.
- Marine Engineering
- Fluid Mechanics