Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Mechanical Engineering
Dual-Pump Vibrational/Rotational Femtosecond/ Picosecond Coherent Anti-Stokes Raman Scattering Temperature And Species Measurements, Chloe Elizabeth Dedic, Joseph D. Miller, Terrence R. Meyer
Dual-Pump Vibrational/Rotational Femtosecond/ Picosecond Coherent Anti-Stokes Raman Scattering Temperature And Species Measurements, Chloe Elizabeth Dedic, Joseph D. Miller, Terrence R. Meyer
Terrence R Meyer
A method for simultaneous ro-vibrational and pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is presented for multi-species detection and improved temperature sensitivity from room temperature to flame conditions. N2∕CH4 vibrational and N2∕O2∕H2 rotational Raman coherences are excited simultaneously using fs pump pulses at 660 and 798 nm, respectively, and a common fs Stokes pulse at 798 nm. A fourth narrowband 798 nm ps pulse probes all coherence states at a time delay that minimizes nonresonant background and the effects of collisions. The transition strength is concentration dependent, while the distribution among observed transitions is related to temperature through …
100 Khz Thousand-Frame Burst-Mode Planar Imaging In Turbulent Flames, James B. Michael, Prabhakar Venkateswaran, Joseph D. Miller, Mikhail N. Slipchenko, James R. Gord, Sukesh Roy, Terrence R. Meyer
100 Khz Thousand-Frame Burst-Mode Planar Imaging In Turbulent Flames, James B. Michael, Prabhakar Venkateswaran, Joseph D. Miller, Mikhail N. Slipchenko, James R. Gord, Sukesh Roy, Terrence R. Meyer
Terrence R Meyer
High-repetition-rate, burst-mode lasers can achieve higher energies per pulse compared with continuously pulsed systems, but the relatively few number of laser pulses in each burst has limited the temporal dynamic range of measurements in unsteady flames. A fivefold increase in the range of timescales that can be resolved by burst-mode laser-based imaging systems is reported in this work by extending a hybrid diode- and flashlamp-pumped Nd:YAGbased amplifier system to nearly 1000 pulses at 100 kHz during a 10 ms burst. This enables an unprecedented burstmode temporal dynamic range to capture turbulent fluctuations from 0.1 to 50 kHz in flames of …