ELECTRIC ARCS IN TURBULENT FLOWS.
Abstract
Experiments are made with the aim to find characteristic differences between electrical arcs in laminar and turbulent flows. To start with the simplest conditions, it is attempted to burn arcs in the fully developed flow region of a flow tube. The tube is 37 cm long and has a 1 cm bore. It is made of electrically insulated copper discs (cascade-chamber) or of quartz glass and is operated with 25 amp DC for durations of 1/2 sec. Highly preheated carbon-dioxide gas of 3.1 atm. pressure from a plasma generator is injected into the tube to shorten the thermal entrance length. Measurements of the electrical potential along the flow tube show that the electrical gradient reaches asymptotically constant values at the end of the flow tube, even for flow velocities as high as 250 m/sec. At these velocities the gradient is about twice as large as compared to gradients for arcs with speeds smaller than 20 m/sec. High speed photography with exposure times of 2 micro sec. reveals that the low velocity arcs are in a quiet, apparently laminar mode, whereas the high velocity arcs are moving violently and with apparent randomness. The flow velocity of the high speed arcs still increases considerably at the end of the flow tube. This suggests that still larger l/d values must be used to reach fully developed flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1964
- Accession Number
- AD0608938
Entities
People
- Gerhard Frind
Organizations
- General Electric