Dr. Robert Pitz, Professor and Chair of the Department of Mechanical Engineering, Vanderbilt University, spoke at the seminar organized by CCRC. Prof. Pitz described a new method for non- intrusive molecular velocity measurement called ‘Hydrogel Tagging Velocimetry’ (HTV).
The HTV method has been applied to measure velocity in Laboratory airflows and combustion exhausts. In this method, an ArF excimer laser (193nm) dissociates water vapor in air or combustion flows to form hydroxyl (OH). Multiple laser lines produce an OH grid (e.g., 11*11) that marks a region of gas flow at known time. The molecular grid is allowed to covert for a fixed time delay (1-50 µs).
Also, a new N2O molecular tagging velocimetry method was described where nitrous oxide (laughing gas) is added to the gas flow. Here, an ArF excimer laser dissociates N2O to form O(1D) that subsequently reacts with N2O to form a NO grid. The NO grid is tracked in time to determine the velocity. The NO formation time and applicability of N2O MTV to high-speed flow will be discussed.
The seminar and the Q&A that followed enlightened the CCRC students, researchers and scientists further on HTV.