Development of a Hydroduct

Citation

Anderson, Roy Gene and Rush, Charles Wesley and McClellan, Thomas Rufus (1947) Development of a Hydroduct. Engineer's thesis, California Institute of Technology. doi:10.7907/7PWR-0P18. https://resolver.caltech.edu/CaltechETD:etd-12032008-155842

Abstract

This report presents the results of experiments on a device for producing thrust for underwater propulsion. The principle of the device is based on accelerating a large mass of water by expansion of a small mass of gas, the gas being injected continuously into the water. The investigation consisted of tests conducted on ducts of several different designs; varying the exit area of the duets, the water and gas flow, and the method of injecting and mixing the gas and water.

Using hydrogen gas at a rate of 0.0165 lbs/sec at a water flow rate of 27.4 lbs/sec, a maximum gross thrust of 29.2 lbs was obtained. At this water flow rate the internal friction drag of the duct was 20.5 lbs, giving a net thrust of 8.7 lbs. The effective exhaust velocity for these flow rates was 56,900 ft/sec.. ThAt is equivalent to a specific impulse of 1,770 sec., whereas a good conventional rocket fuel would have a specific impulse of about 250 sec. At low gas flow rates an effective exhaust velocity of 296,000 ft/sec. was obtained. However, at this low gas rate the gross thrust was less than the internal friction drag of the duct.

Effective exhaust velocity is defined as gross thrust divided by the mass flow rate of gas, and has the dimensions of velocity.

Thesis Files