Electrolysis Bubble Noise in Small-Scale Tests of a Seawater MHD thruster
Abstract
Sound pressure levels were measured during the electro lysis process of seawater in a magnetohydrodynamic-type channel, but without an applied magnetic field. The test configuration was a small-scale version of a seawater magnetohydrodynamic (MHD) thruster and the test conditions were similar to those which might occur in an undersea MHD-powered vessel. The electrolysis of sea water at current densities up to 0.3 A/cm2 produced broad-band noise at frequencies above 2 kHz and up to 20 kHz. Most of the acoustic energy was to the 2 to 6 kHz range. A few noise peaks were superimposed upon the broad-band noise. The most significant of these appeared to be associated with transverse standing waves in the flow channel. The increased noise levels resulted from the oscillation of hydrogen bubbles produced during electrolysis as these hydrogen bubbles (1) detach from the electrode surface and (2) coalesce, forming larger bubbles. The test data suggest that bubble coalescence is the principal noise source. Bubble diameter, inferred from the noise data, appears to be in the range of 0.075 to 0.15 mm. The bubble noise was relatively easy to measure and to discern from test facility noise and flow-induced noises. Some comparisons with previous noise measurements are made and various factors that influence the bubble noise are outlined. Keywords: Underwater propulsion; Magnetohydrodynamics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1990
- Accession Number
- ADA227548
Entities
People
- Kenneth E. Tempelmeyer