Pressure sensing with two-color laser absorption spectroscopy for combustion diagnostics

Area of Science:

• Combustion diagnostics
• Laser spectroscopy
• Physical chemistry

Background:

• Contact sensors for combustion pressure measurement disturb flows and have temperature limits.
• Noncontact methods are needed for accurate, high-temperature combustion diagnostics.

Purpose of the Study:

• To propose and demonstrate a novel noncontact two-color pressure sensing method using tunable diode laser absorption spectroscopy (TDLAS).
• To enable accurate pressure measurements in high-temperature combustion environments.

Main Methods:

• Utilized the linear combination of collision-broadened linewidths of two H2O absorption lines near 1343 and 1392 nm.
• Employed tunable diode laser absorption spectroscopy (TDLAS) for noncontact measurement.
• Validated the method in high-temperature environments (up to 1300 K) and across a pressure range (1-5 bars).

Main Results:

• Successfully measured pressure from 1 to 5 bars at temperatures up to 1300 K.
• Achieved measurement errors within 3%.
• Demonstrated independence from concentration influence, a key advantage over prior TDLAS methods.

Conclusions:

• The proposed noncontact two-color TDLAS method is feasible and accurate for high-temperature combustion pressure sensing.
• This method overcomes limitations of contact sensors and is unaffected by concentration.
• It can be integrated with existing TDLAS thermometry for fast, online, multi-parameter combustion diagnostics.