Experimental Study of Hot-Sphere Anemometer Response in Stratospheric Environment

Area of Science:

• Aerospace Engineering
• Atmospheric Science
• Instrumentation and Measurement

Background:

• Accurate wind speed measurement is critical for stratospheric aircraft thermal performance and attitude control.
• Traditional wind speed sensors struggle in low-pressure stratospheric environments due to decreased air density.
• Existing methods often fail to meet the stringent accuracy requirements for stratospheric flight.

Purpose of the Study:

• To develop and validate a novel wind speed simulation system for low-pressure environments.
• To investigate the performance of thermal sphere anemometers under stratospheric conditions.
• To analyze the impact of low pressure and low Reynolds numbers on anemometer accuracy.

Main Methods:

• Development of a wind speed simulation system using a rotation method within a space environment simulation chamber.
• Integration of a high-precision turntable for controlled low-pressure testing.
• Response testing of a constant heat flow thermal sphere anemometer from 1 kPa to 30 kPa.

Main Results:

• Observed increasing nonlinearity in probe signals at extremely low Reynolds numbers, impacting response curves below 15 kPa.
• Found that hot-sphere probe sensitivity remained stable above 5 m/s but decreased nonlinearly below 5 m/s as pressure dropped.
• Analyzed the influence of different interpolation methods on wind speed conversion errors.

Conclusions:

• The developed simulation system effectively characterizes anemometer performance in low-pressure stratospheric conditions.
• Nonlinearity and reduced sensitivity at low pressures and low wind speeds present significant challenges for stratospheric wind measurement.
• The findings provide crucial data for improving wind speed measurement technologies for future stratospheric aircraft.