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Full-Text Articles in Mechanical Engineering

Broadband Coherent Anti-Stokes Raman Scattering Spectroscopy Of Nitrogen Using A Picosecond Modeless Dye Laser, Sukesh Roy, Terrence R. Meyer, James R. Gord Nov 2005

Broadband Coherent Anti-Stokes Raman Scattering Spectroscopy Of Nitrogen Using A Picosecond Modeless Dye Laser, Sukesh Roy, Terrence R. Meyer, James R. Gord

Terrence R Meyer

Broadband picosecond coherent anti-Stokes Raman scattering (CARS) spectroscopy of nitrogen is demonstrated using 145-ps pump and probe beams and a 115-ps Stokes beam with a spectral bandwidth of 5 nm. This is, to our knowledge, the first demonstration of broadband CARS using subnanosecond lasers. The short temporal envelope of the laser pulses and the broadband spectral nature of the Stokes beam will enable nonresonant-background-free, single-shot, or time-dependent spectroscopy in high-pressure or hydrocarbon-rich environments. Successful correlation of room-temperature broadband picosecond N2 CARS with a theoretical spectrum is presented.


Ballistic Imaging Of The Liquid Core For A Steady Jet In Crossflow, Mark A. Linne, Megan Paciaroni, James R. Gord, Terrence R. Meyer Oct 2005

Ballistic Imaging Of The Liquid Core For A Steady Jet In Crossflow, Mark A. Linne, Megan Paciaroni, James R. Gord, Terrence R. Meyer

Terrence R Meyer

A time-gated ballistic imaging instrument is used to obtain high-spatial-resolution, single-shot images of the liquid core in a water spray issuing into a gaseous crossflow. We describe further development of the diagnostic technique to improve spatial resolution and present images and statistics for various jets under crossflow experimental conditions (different Weber numbers). Series of these images reveal a near-nozzle flow field undergoing breakup and subsequent droplet formation by stripping. One can also detect signatures of spatially periodic behavior in the liquid core and formation of small voids during breakup.


10 Khz Detection Of Co2 At 4.5 Um By Using Tunable Diode-Laser-Based Difference-Frequency Generation, Terrence R. Meyer, Sukesh Roy, Thomas N. Anderson, Robert P. Lucht, Rodolfo Barron-Jimenez, James R. Gord Oct 2005

10 Khz Detection Of Co2 At 4.5 Um By Using Tunable Diode-Laser-Based Difference-Frequency Generation, Terrence R. Meyer, Sukesh Roy, Thomas N. Anderson, Robert P. Lucht, Rodolfo Barron-Jimenez, James R. Gord

Terrence R Meyer

A compact, high-speed tunable, diode-laser-based mid-infrared (MIR) laser source has been developed for absorption spectroscopy of CO2 at rates up to 10 kHz. Radiation at 4.5 um with a mode-hop-free tuning range of 80 GHz is generated by difference-frequency mixing the 860 nm output of a distributed-feedback diode laser with the 1064 nm output of a diode-pumped Nd:YAG laser in a periodically poled lithium niobate crystal. MIR absorption spectroscopy of CO2 with a detection limit of 44 ppm m at 10 kHz is demonstrated in a C2H4-air laminar diffusion flame and in the exhaust of a liquid-fueled model ...


Diode-Laser-Based Ultraviolet-Absorption Sensor For High-Speed Detection Of The Hydroxyl Radical, Thomas N. Anderson, Robert P. Lucht, Terrence R. Meyer, Sukesh Roy, James R. Gord May 2005

Diode-Laser-Based Ultraviolet-Absorption Sensor For High-Speed Detection Of The Hydroxyl Radical, Thomas N. Anderson, Robert P. Lucht, Terrence R. Meyer, Sukesh Roy, James R. Gord

Terrence R Meyer

A new diode-laser-based UV-absorption sensor for high-speed detection of the hydroxyl radical (OH) is described. The sensor is based on sum-frequency generation of UV radiation at 313.5 nm by mixing the output of a 763-nm distributed-feedback diode laser with that of a 532-nm high-power, diode-pumped, frequency-doubled Nd:YVO4 laser in a B-barium borate crystal.