The regenerative blower provides air flow through structures or systems that have relatively high flow resistance. Specifically, the regenerative blower was designed to provide a flow of ventilation gas through a spacesuit and its portable life support system (PLSS). Since the ventilation gas is primarily oxygen, fire prevention is a critical design requirement.
The invention is a very compact blower that can achieve high pressure rise with low rotating speed. The unique, regenerative impeller impels the circulating gas and boosts its pressure several times before the gas leaves the blower, enabling a much higher pressure rise than conventional blowers at the same rotating speed. A unique brushless DC motor drives the impeller using a stator coil that is hermetically sealed from the circulating gas.
The regenerative blower will improve overall safety, thanks primarily to its low rotating speed and the materials of construction. At the blower’s nominal rotating speed of 5,400 rpm, the tip speed of the impeller is only 28 m/s. This is less than the 30 m/s limit on particle impact speed to avoid flammability concerns in an oxygen environment. The low rotating speed enables fabrication of the impeller from a wide variety of materials, limited primarily by fabrication methods. Therefore, the impeller can be made from SLA plastics or machined metals, graphite, or ceramics. Likewise, the materials for the remaining blower components (cover shells, stripper seal, and flow channel core) can be chosen primarily for good safety characteristics. The nominal bearing lubricant (Krytox) is also rated safe for operation in an oxygen environment.
Most of the blower components will be combined into subassemblies for ease of maintenance and repair; for example, the cover subassembly will include the stator coils and stator flux ring. Because the tolerances for the regenerative blower are not extremely tight [adequate seals require clearances of only about 0.003 in.(≈76 μm)], it is expected that disassembly and reassembly will be simple, and can be performed in situ if necessary for regular inspection, maintenance, or repair.
This work was done by Michael Izenson and Weibo Chen of Creare Inc. for Johnson Space Center. For further information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-24630-1