Report No: DOT/FAA/AM-98/4

Title and Subtitle: Effect of an airplane cabin water spray system on human thermal behavior: A theoretical study using a 25-node model of thermoregulation

Report Date: February 1998

Authors: Wolf, M.B.1, and Garner, R.P. 2

Abstract: This study was conducted to assess the effect of an aircraft cabin water spray system on thermoregulatory responses of passengers after being wetted by the spray system. A mathematical model was developed that could adequately describe experimentally determined transient changes in metabolic rate (MR), and core and skin temperatures of human beings exposed to water-immersion conditions (0 to 28°C). The model was the basic 25-node description of Stolwijk and Hardy as modified to apply to a male with medium fat content. The MR increase induced by shivering was described by 3 components sensitive to 1) time-rate of change of skin temperature, 2) the product of changes in skin and head-core temperatures and 3) the product of skin temperature change and the time-rate of change of head-core temperature.

The model was also able to closely predict the changes in MR and skin temperatures induced by exposure to cold air. However, the predictions of rectal temperature changes were in the opposite direction to the experimental data for this case. The model was modified to describe the effects of spraying individuals with water on their heads, arms and torsos to simulate the action of a cabin water spray system activated by a fire in an airplane. The model predicted that an individual, after being sprayed and exiting into a cold and windy environment, would encounter only a minor increase in thermal stress compared to the dry state. We conclude that mathematical simulation is an effective method of predicting thermal behavior of humans under a variety of cold conditions.

Key Words: Aviation safety, aircraft, passengers, mathematical model, human thermoregulation, water immersion

No. of Pages: 22