Application of holographic interferometry and 2D PIV for HSC convective flow diagnostics

Variations of temperature and velocity fields in a Hele-Shaw convection cell (HSC) were investigated using a holographic interferometry and 2D PIV system with varying Rayleigh number. To measure quasi-steady variation of the temperature field, two different measurement methods of holographic interferometry-the double-exposure method and the real-time method-were employed. In the double-exposure method, unwanted waves were eliminated effectively using a digital image processing technique. The reconstructed images are clear, but transient flow cannot be reconstructed clearly. On the other hand, transient convective flow can be reconstructed well using the real-time method. However, the fringe patterns reconstructed by the real-time method contain more noise than the double-exposure method. Experimental results show a steady flow pattern at low Rayleigh numbers and a time-dependent periodic flow structure at high Rayleigh numbers. The periodic flow pattern at high Rayleigh numbers obtained by the real-time holographic interferometer method is in good agreement with the PIV results.