The aim of this research was to improve the thermal protection of divers in an underwater environment using currently available, but underutilized, passive and/or active technologies. This dissertation was divided into four separate phases each focusing on a particular goal contributing to the overall aim.
Phase 1 . The purpose of this phase was to measure the thermal resistance of foam neoprene wetsuit insulation under hyperbaric pressure, and show that the thermal properties of foam neoprene under hyperbaric pressure cannot be predicted by theoretical means, and that uni-axial pressure cannot simulate hyperbaric compression. The thermal conductivity and compressive strain of foam neoprene were measured under hyperbaric pressure. In parallel, unconstrained uni-axial compressive strain data were collected.
Phase 2 . The purpose of this phase was to present a new underwater thermal insulation designed for flexibility and high thermal resistance. An underwater insulation was proposed as a hybrid composite of two constituents: syntactic foam and an aerogel blanket. A configuration was selected based on optimal thermal resistance and was tested for thermal resistance and compressive strain to a pressure of 1.2 MPa (107 msw) for five continuous pressure cycles. The hybrid insulation had a thermal resistance significantly higher than both foam neoprene and underwater pipeline insulation at atmospheric and elevated hyperbaric pressures (1.2 MPa).
Phase 3 . The purpose of this phase was to compare the thermal resistance of a wetsuit fabricated from hybrid insulation to a foam neoprene wetsuit. The thermal resistance of the hybrid wetsuit and a foam neoprene wetsuit was measured on a human test subject in water at 0.25 MPa (15.25 msw) of hyperbaric pressure. Measurements showed that although certain body regions of the hybrid wetsuit had a higher thermal resistance than foam neoprene, the overall thermal resistance of the hybrid wetsuit was 41% less than a foam neoprene wetsuit, and 51--88% less than predicted values.
Phase 4 . The purpose of this phase was to evaluate the active requirements to thermally sustain a diver in varying ambient water temperatures. Using a foam neoprene wetsuit (6.5 mm and 3 mm) the active heating/cooling requirements to keep a diver in thermal balance and comfort in water temperatures varying from 10--40 °C was assessed while wearing a water circulating tubesuit perfused by active heating/cooling units (Med-End Inc, Ottawa, On). (Abstract shortened by UMI.)
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