Laser ignition and flame propagation of methanol-air mixture in a constant volume combustion chamber

ABSTRACTThe combustion performance of laser-ignited methanol-air mixture in a constant volume combustion chamber was investigated using the Schlieren photography technique. The experimentation was conducted at 5, 7, 9, and 11 MPa fuel injection pressure and 363 K initial chamber temperature using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser of 1064 nm wavelength. The gasoline direct injection (GDI) system was used for injecting the fuel at different pressures inside the chamber. The laser beam is focused into the chamber using a 150 mm focal length lens, and laser energy of 200 mJ was used for all experimentation. The Schlieren system was used for capturing flame propagation of methanol-air mixture for different equivalence ratios. The pressure-time history for equivalence ratio (ϕ) of 0.8, 0.9, and 1.0 was plotted and analyzed at different chamber filling pressures. Flame propagation was found faster for ϕ of 1.0 due to higher laminar velocity than 0.8 and 0.9. Flame visualization showed that the flame attains the ellipsoid shape during the early stage of ignition. It generates two lobes in the vertical direction and then again expands in a horizontal direction toward the ignition source. For all equivalence ratios, the flame propagation toward the incoming laser source (X-) was observed faster compared to the flame propagation in the direction and perpendicular to the laser beam direction. For all equivalence ratios, higher laminar flame speed was observed at 5 MPa injection pressure; however, it decreases as the injection pressure increases. At ϕ of 1.0 and 11 MPa injection pressure, the maximum peak pressure of 0.67 MPa and combustion duration of 19.3 ms were noted. At 9 MPa injection pressure and ϕ of 1.0, the peak pressure and combustion duration was found as 0.61 MPa and 19.4 ms, respectively. At ϕ of 0.8, the peak pressure and combustion duration were observed 0.27 MPa with 34.6 ms duration and 0.47 MPa with 36.9 ms duration at 5 MPa and 11 MPa injection pressures, respectively.KEYWORDS: Combustion durationflame propagationlaser-ignitionmethanolpressure-time history Highlights Laser-ignited combustion of methanol-air mixture in the constant volume combustion chamber (CVCC) at different equivalence ratios (ϕ) was investigated.The maximum flame propagation in all directions was observed at ϕ of 1.0. However, at all ϕ, the flame propagation towards the incoming laser source (X-) was observed at maximum.Peak pressure increases with an increase in fuel injection pressure from 5 MPa to 11 MPa and ϕ from 0.8 to 1.0.Maximum pressure of 0.67 MPa was observed at an ϕ of 1.0 at a fuel injection pressure of 11 MPa.Minimum combustion duration was observed at 5 MPa fuel injection pressures.Nomenclature CVCC=Constant Volume Combustion ChamberNd:YAG=Neodymium-doped Yttrium Aluminum Garnetϕ=Equivalence ratioGDI=Gasoline Direct InjectionLI=Laser IgnitionSI=Spark IgnitionCI=Compressed IgnitionMIE=Minimum Ignition Energyfps=Frames Per SecondNOx=Nitrogen OxideCO=Carbon MonoxideCO2=Carbon DioxidePM=Particulate MatterHC=HydrocarbonsTHC=Total HydrocarbonsEHN=2-ethylhexyl nitrateCH3OH=MethanolX-=Flame propagation toward the incoming laser beamX+=Flame propagation in the direction of the laser beamY=Flame propagation in perpendicular to the laser beamMPa=Mega PascalK=KelvinSL=Laminar Flame SpeedSLo=Laminar Flame Speed at a reference conditionPo=Reference Pressure (MPa)To=Reference Temperature (K)α and β=Constants for given fuelAcknowledgementsThis research was assisted by the Technical Education Quality Improvement Program (TEQIP) at the College of Engineering, Pune.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by the Technical Education Quality Improvement Program (TEQIP) at the College of Engineering, Pune. [TEQIP-III/MH/COEP/43].Notes on contributorsShrimanitni Shantaram PatilShrimantini Shantaram Patil is a research scholar at the CoEP Technological University, Pune, India. She earned his Bachelor's Degree in Mechanical Engineering from Shivaji University, India. She earned his Master's Degree in Heat Power Engineering from Sinhgad College of Engineering Pune, Savitribai Phule Pune University, India. She completed her PhD in Mechanical Engineering from the College of Engineering, Pune, Savitribai Phule Pune University, India. She has published more than 7 papers in various national and international journals.Prashant Mahadev PatanePrashant Mahadev Patane is a research scholar at the CoEP Technological University, Pune, India. He earned his Bachelor's Degree in Mechanical Engineering from Shivaji University, India. He earned his Master's Degree in Thermal Engineering from the College of Engineering Pune, Savitribai Phule Pune University, India. Since 2018, he is pursuing a Ph.D. in Mechanical Engineering from the College of Engineering Pune, Savitribai Phule Pune University, India. He has published more than 7 papers in various national and international journals.Milankumar Ramakant NandgaonkarDr. Milankumar Ramakant Nandgaonkar is a Professor at CoEP Technological University, Pune, India. He earned his Ph.D. in Mechanical Engineering from Amravati University, India, in 2002. His research area includes I.C. Engines, laser Ignition, alternative fuels and CFD. Dr. Nandgaonkar has developed a state-of-the-art laser combustion research laboratory, I.C. engine and fuel testing laboratory and battery testing laboratory at the College of Engineering, Pune. He has developed a mathematical model for predicting soot and NOX emissions of DI Diesel engines under transient operating conditions. He has published more than 60 papers in various national and international journals.