Laboratory turbulence generator for evaluating nodal sensors

Turbulence is often simulated in a laboratory environment using optical phase plates to generate wave-front delays following Kolmogorov statistics. While this works well with optical signals, it cannot be used with nodal (point) sensors that measure turbulence based on temperature or refractive index. Nodal sensors, such as differential temperature sensors, are evaluated in field tests with no control over turbulence strength or weather conditions. As an alternative to field testing, we developed a simple in-air laboratory turbulence generator by extending concepts used to create turbulence in water tanks. As part of this effort, we examined the generated turbulence to find inertial range and outer scale. We found statistical averaging time to be critical to have sufficient sampling to generate “good” turbulence and that it was important to encourage convection through use of both heating and cooling. The work of three groups that have used a similar design to test sensors will be presented.