NASA ISS portable fan assembly acoustics

Abstract

The Portable Fan Assembly (PFA) is a variable-speed fan that can be used to provide additional ventilation inside International Space Station (ISS) modules as needed for crew comfort or for enhanced mixing of the ISS atmosphere. This is important to avoid carbon dioxide (CO2) pockets that can build up because of the lack of natural convection in the microgravity environment. This fan can also be configured with a lithium hydroxide (LiOH) canister for CO2 removal in confined areas partially or fully isolated from the primary Environmental Control and Life Support System (ECLSS) on ISS, which is responsible for CO2 removal. The primary focus of this paper is to document radiated noise and the acoustic attenuation effects realized when circulating air through the PFA operating in its CO2 removal kit (CRK) configuration with a LiOH canister (sorbent bed) installed over the fan outlet, in place of outlet muffler. This report also documents the acoustic performance of the PFA with inlet and outlet mufflers in place. Lastly this paper documents an estimate of the acoustic insertion loss associated with a LiOH canister.