Measurement of three-dimensional flow speed and direction in wildfires

We report on the ongoing development of a new style of instrument package to measure three-dimensional flow speed and direction in wildland fires. The all-metal construction and lack of moving parts enables the instrument to survive immersion in flames for measurements in all fuel types. Disk style probes are used instead of the more common bi-directional probe to improve angle sensitivity of pressure measurement. Improved angular discrimination will permit calculation of fully three dimensional flow direction in addition to flow speed. An instrument package incorporating the disk anemometry system was developed and underwent preliminary testing. While the disk-style probe shows some improvement in angular sensitivity over a bi-directional probe, further improvement will result in greater tolerance in small inaccuracies in pressure measurement.