Electric fields in a counterflow nonpremixed flame: measurement and simulation

Area of Science:

• Combustion Science
• Plasma Physics
• Fluid Dynamics

Background:

• Electric fields influence flame dynamics and flow fields.
• Numerical models for charged species exist but require experimental validation.
• Electric Field Induced Second Harmonic generation (EFISH) is a promising but challenging technique for electric field measurement in flames.

Purpose of the Study:

• To propose and validate measurement and calibration schemes for quantifying EFISH signals in laminar counterflow nonpremixed flames.
• To compare experimental electric field measurements with numerical simulations.
• To identify discrepancies for improving combustion models.

Main Methods:

• Developed measurement and calibration schemes for EFISH signal quantification.
• Utilized an in-house multi-physics Computational Fluid Dynamics (CFD) code for numerical simulations.
• Conducted experiments in a laminar counterflow nonpremixed flame.

Main Results:

• Quantified electric fields from EFISH measurements showed good agreement with CFD simulations.
• Observed null electric fields near the flame in the sub-saturated regime due to electric field screening.
• Discrepancies in the saturated regime highlighted potential limitations in current ion mechanisms and transport models.

Conclusions:

• Experimentally quantified electric fields provide valuable validation data for combustion models.
• The study suggests a need for refinement of ion kinetic mechanisms and transport models.
• Future work should focus on in-situ measurement of charged species in electric fields.