Experimental Research
Experimental Research
During those few early years of NASA I made a foray into experimental work. I don't intend to describe in detail all of this work, because the technical aspects of the research, while fascinating to me, would have little meaning to someone without an engineering degree. However, I am going to tell the story of the first project because it demonstrates attitudes of NASA engineers in the face of successful, innovative work.
My first project was in the area of magnetohydrodynamics (the interaction of electric and magnetic fields with a fluid in motion). The motion of vehicles in the upper reaches of the atmosphere initiated an enhanced interest in low density fluid dynamics and even free-molecule flows. The possibility of designing hypersonic military and commercial airplanes for flight at these altitudes would require a propulsion system that could be used at speeds beyond the practical limits of jet engines. The concept that seemed to fulfill this requirement was an ionized gas which would be driven by the interaction of electric and magnetic fields. This possibility attracted attention at several of the NASA laboratories, including Langley, and each lab began work on designing and testing a workable device.
This concept also gained attention from the standpoint of submarine design, because it offered the possibility of replacing the noisy thrashing motion propellers. Sea water is a good conductor, and so no additional ionization is required. The idea gained so much attention that it became the concept on which the Tom Clancy book, The Hunt for Red October was based.
However, an apparatus that would drive a gas continuously at a sufficient current and a gas density high enough to be useful seemed to defy all of the efforts. The simple principle behind this concept is called the Lorentz force. If we have a fluid in a channel, with a current flowing horizontally across the channel, and we apply a magnetic field vertically through the channel, then the charged particles in the current would be blown downstream and apply a force to the flow in that direction. The designs based on this principle didn't work, because as soon as the magnetic field was applied, and the charged particles were blow into the cold gas the voltage required to maintain the arc was not sufficient, and it simply blew out. A way of obtaining a high voltage at a high current is to discharge a condenser through the gas. It works; but only for a fraction of a second, and then the condenser has to be recharged. Thus, the operation is periodic with widely spaced spurts. But it is useless because a continuous operation is required.
I read everything I could find on the Lorentz force in gases, and finally found what I was looking for in an Electrical Engineering journal. The article was on managing devices that operate at very high currents. For practical reasons the circuit breakers should not be mechanical. The solution obtained was to use the Lorentz force: pass the current across a gap and apply a magnetic field perpendicular to it to blow it out.
So now the solution seemed obvious. We needed a circuit breaker that would fail. That is, it would blow the arc into the cold adjacent gas but with a voltage capable of overcoming the increased resistance so that the circuit current would not be interrupted. I talked my supervisors into letting me give it a try. They assigned a couple of experimentalists to me, we ordered a custom power supply with the capability of supplying a high DC current (>30 amps) at a high enough voltage that it could overcome the resistance as the arc blew into cold gas, set up the device, and it worked nicely on the very first try!
In order to demonstrate that the device was actually pumping gas, The experimentalists, Joe and Bill mounted a vane upstream of the arc, which would be deflected by the return flow before it entered the arc area, that is, by the gas that had been pumped a full circuit around the tube. Then they filmed the vane deflecting when we turned on the device, thereby proving that the gas was actually being pumped around the complete tube circuit.
We did not advertise this result immediately because there was an interlab conference on this kind of research scheduled in the near future at NASA's Lewis Research Center, and we wanted to prepare a publication on the device before presenting the results openly at that conference. Most of the research labs had a group working on this kind of magnetofluiddynamics research, with experimental work either ongoing or in the planning stage. Our little group was by far the newcomer to the group, which included a separate group at LRC that had been working on the problem for well over a year, with a considerable investment in both money and manpower.
Apparently the talks had been ordered alphabetically, because I found that my talk had been scheduled near the top, as one of the first on the prepared agenda. But just before the conference began, I was informed that I would be the last speaker. There were about a dozen talks, most of which described proposed designs and descriptions of both theoretical and design difficulties. Some included experimental attempts, all of which failed to yield the desired results. After each talk there was an informal question and answer period, which usually dwelt on possible ways to overcome the problems encountered or anticipated.
When it finally came time for my talk, I gave a brief explanation of our approach, and showed the film of its operation, then asked for questions. Absolute silence. And so the conference ended.
But that was not the end of the story. Just as some of my theoretical work had aroused resentment in some who had approached the theory incorrectly, this experimental result aroused some resentment in some of the attendees, but it elicited absolute furor in the competing branch at LRC. They sought revenge, and they got it - which taught me much about ethics, or lack of it, in a research organization.
Return to table of contents for this label:
Comments
Post a Comment