Abstract

This paper describes the design, construction and testing of a thermochromic liquid crystal based, non-intrusive, surface flow visualization system. The system uses a pin-finned heat sink in contact with a thin sheet of liquid crystals and is easily mounted in a wind tunnel. When heated and placed in a fluid flow, the pin-finned heat sink produces teardrop-shaped thermal wakes that indicate the direction of the flow. We performed an optimization experiment and determined that the best flow visualization images are achieved for heat sink base temperatures that are 10–20 °C above the liquid crystal activation temperature. Under these conditions, the full range of the liquid crystals is utilized. We present liquid crystal flow visualization results for flow about streamlined and blunt objects and demonstrate the performance of the liquid crystal surface. We also compare liquid crystal images for flow about a blunt body to PIV data and show good qualitative agreement. The technique is repeatable, non-intrusive and instructive for learning about surface flow characteristics.

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