Development of a low-cost, computer-controlled, portable LITA system for high-pressure combustion measurements

We propose to engineer a low-cost computer-controlled optical diagnostic system for measuring sound speed, thermal diffusivity, density, and velocity. This system will use laser-induced thermal accoustics (LITA), a transient-grating technique capable of making accurate single-shot measurements in luminous, multiphase, high-pressure flows. The LITA signal intensity is quadratic in fluid density for a given gas composition, making it ideal for high-pressure applications. The data from LITA signals will be extracted in real time via FitLITA, a fast and accurate signal analysis program that we have developed.We propose to engineer a system that a technician can install and operate in harsh test-stand conditions. We will design the remote computer controlled system to be immune to noise, shock, vibrations, and temperature fluctuations that are encountered in such environments.The system that we propose to design and build will be portable and capable of automatic alignment and three-dimensional spatial scanning. A system of coordinated electro-mechanical beam-positioners will allow remote computer control of beam-crossing angles and alignment, two important factors in LITA measurement. FitLITA can provide measurements of and account for beam misalignment. These measurements will be used to alleviate beam-steering effects and automatically correct beam alignment.