1990-07-01

An Air Bearing Fan for EVA Suit Ventilation 901432

AiResearch has investigated the application of high-speed axial fan technology for extravehicular activity (EVA) space suit ventilation. Design studies have shown that, using fine-scale aerodynamic blading, the fan can be optimized for high performance at the low flows needed for ventilation. Significant savings are achieved in size, weight, and input power.
The key technology elements are the self-acting air bearing and the permanent magnet motor. The compliant foil bearing uses the tip speed of the rotor to pump the surrounding air into the lubricating film. The bearings are free of potential contaminants to the EVA suit because no other lubrication is required. The permanent magnet brushless dc motor allows the fan to operate at the high rotational speeds needed for efficient axial flow aerodynamics. The integral power electronics provide flexibility in fan operation. By controlling motor current, the fan runs at constant load torque with the speed and flow rate resulting. The fan can thus accommodate changes in suit air density and desired ventilation rates.
The air bearing suit fan delivers a nominal 0.17 cu m/min (6 cfm) at 1.24 kPa (5.0 in. H2O) pressure rise using 13.8 w of input power. Including the power electronics, the unit weighs 0.40 kg (0.90 lb) and uses an envelope of 6.5 cu in.

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