# Air Speed Sensing Using Solid-State Thermal Impedance

## This course shows you how to measure air speed using solid-state thermal impedance techniques

In this course you will learn how to measure air speed using solid-state thermal impedance techniques. Our methodology uses a heated transistor, a closely coupled thermal sensor measuring the heat generated, and a solid-state air temperature reference sensor to sense and compute the air speed or flow rate.

Air flow is computed using forced convection heat transfer principles over a flat plate using Newton’s law of cooling. In this law is used, the Nusselt number, that accounts for the heat transfer coefficient and the Prandtl number, which accounts for the velocity and thermal boundary interactions. Measurement is limited to laminar flow and a flat plate type detector/sensor.

This relatively inexpensive way to measure air velocity can be calibrated to fit a variety of applications. The class will illustrate the experiments, elaborate on the results, and compare them with a hot-wire anemometer.

### Curriculum22 min

• Syllabus
• Introduction 2 min
• Hot-Wire Anemometry 3 min
• Solid State Thermal Impedance Method 4 min
• Demo
• Setup 3 min
• Air Speed Measuring 1 min
• Results 3 min
• Conclusions 6 min

In this course you will learn how to measure air speed using solid-state thermal impedance techniques. Our methodology uses a heated transistor, a closely coupled thermal sensor measuring the heat generated, and a solid-state air temperature reference sensor to sense and compute the air speed or flow rate.

Air flow is computed using forced convection heat transfer principles over a flat plate using Newton’s law of cooling. In this law is used, the Nusselt number, that accounts for the heat transfer coefficient and the Prandtl number, which accounts for the velocity and thermal boundary interactions. Measurement is limited to laminar flow and a flat plate type detector/sensor.

This relatively inexpensive way to measure air velocity can be calibrated to fit a variety of applications. The class will illustrate the experiments, elaborate on the results, and compare them with a hot-wire anemometer.

• Syllabus
• Introduction 2 min
• Hot-Wire Anemometry 3 min
• Solid State Thermal Impedance Method 4 min
• Demo
• Setup 3 min
• Air Speed Measuring 1 min
• Results 3 min
• Conclusions 6 min