Memory Tube Diffusion Studies
Abstract
Memory tubes were devised to sample the gas composition in the Space Shuttle Main Engine (SSME) duct at many locations (33-100) using only a few mass spectrometers. The feasibility of this technique was evaluated by examining the capability of long tubes to transport and store time-varying gas composition data with sufficient time resolution to rule out the existence of hazardous hydrogen-air mixtures in the duct. The procedure was 1) to examine the theoretical and experimental behavior of gas mixtures during flow and storage in long tubes, 2) to optimize the flow conditions and tube size for maximum resolution for up to 1 hr storage, and 3) to characterize the time resolution of the memory tube so that computer deconvolution could be used to maximize information recovery. In this report, we present the results of the memory tube experiments conducted in the Aerophysics Laboratory. The diffusion behavior of oxygen and helium was in rough agreement (0.035 in. wall thickness). Both 300 and 75 ft memory tubes were studied. Time resolution, as measured by the FWHM broadening of very short gas pulses, was 0.380 and 0.350 sec, respectively, for oxygen in 1/4 and 3/8 in. OD memory tubes, and 0.300 and 0.270 sec for helium in 300 ft tubes. The results indicate that information is present up to 4 or 5 Hz in 300 ft tubes and 9 to 10 Hz in 75 ft tubes. Deconvolution, or frequency compensation, should enable reconstruction of input pulses of approximately 0.1 sec FWHM in the 75 ft tubes and 0.2 sec FWHM in the 300 ft tubes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1988
- Accession Number
- ADA197511
Entities
People
- Laurence R. Martin
- Robert A. Hertz
- Robert N. Abernathy
- Ronald B. Cohen
Organizations
- The Aerospace Corporation