Jet-Cavity Interaction Studies
Abstract
Water tunnel experiments are conducted to quantify the effect of the jet on the cavitation number and on the dimensions of the cavity. Nearly every detail of the design of a supercavitating body ultimately relies upon an accurate prediction of the diameter and length of the generated cavity, and while the magnitude of the cavity size is dependent on cavitator drag, the relationship between length and diameter is solely dependent upon the cavitation number, sigma. The proposed 36?month research project undertaken by The Applied Research Lab – Penn State University is intended to clarify the effect of a propulsion jet on a ventilated cavity enveloping a supercavitating high?speed body. In particular, we propose to quantify the effect of the jet on the cavitation number and on the dimensions of the cavity through contained model testing in the 48?inch diameter water tunnel at ARL?Penn State. Prior research undertaken at ARL?Penn State has confirmed that a jet issuing from a supercavitating body does influence the cavitation number of the enveloping cavity. Given the relationship between cavitation number and ventilated cavity dimensions, it is therefore expected that a propulsion jet also affects the dimensional relationships of a cavity. The proposed research focuses on the following questions: 1. Is the unique relationship between cavitation number and cavity dimensions, as reported in the literature for unpropelled cavities, also valid for propelled cavities? 2. What is the scaling relationship between cavity dimensions, cavitation number, and jet parameters, under the influence of a propelling jet? 3. How is the scaling relationship between cavity dimensions and cavitation number and jet mediated by parameters such as body length and jet nozzle diameter? The proposed thirty?six month research project to address the questions summarized above will focus on experimental investigations of the behavior of a supercavity enveloping a water tunnel model. In the first year, new dimensional data will be acquired utilizing hardware consistent with that used in the prior research. In the second year new hardware will be utilized to permit the exploration of the influence of significantly greater jet flow rates. In the third year, the investigation will focus on model length and jet character (sonic versus supersonic flow, gas density variations).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 23, 2016
- Source ID
- N000141612707
Entities
People
- Michael Moeny
Organizations
- Office of Naval Research
- Pennsylvania State University
- United States Navy