How Wind Tunnel and Associated Instrumentation Are Used for Performing Aerodynamic Studies — Lesson 4

This lesson covers the use of different types of instrumentation to perform aerodynamic studies with examples from both low and high-speed tunnels. It begins with an explanation of how velocity is calculated from pressure in low-speed applications using a pitot static tube. The lesson then moves on to discuss the use of a hot wire anemometer for measuring velocity fluctuations in a turbulent flow field and a preston tube for measuring skin friction coefficient. The lesson also covers the categorization of instruments into mechanical and electronic, and the importance of calibrating wind tunnels before conducting experiments. It concludes with a discussion on how to measure the test section Mach number in a supersonic wind tunnel.

Video Highlights

01:24 - Introduction to the use of a preston tube for measurements of skin friction coefficient.
04:37 - Explanation of the use of a hot wire probe for test section turbulence intensity evaluation.
08:16 - Discussion on the use of a hot wire anemometer for turbulence intensity evaluation.
25:18 - Discussion on the use of a wedge model for measuring the test section mach number in a supersonic wind tunnel.

Key Takeaways

- Velocity in low-speed applications is generally calculated from pressure using a pitot static tube.
- A hot wire anemometer is used to measure velocity fluctuations in a turbulent flow field.
- A preston tube is used to measure the skin friction coefficient.
- Instruments are broadly categorized into mechanical and electronic.
- It's crucial to calibrate wind tunnels before conducting experiments.
- The test section Mach number in a supersonic wind tunnel can be measured using various techniques.