![Table 1. Laminar flame properties. NA denotes flame cellular from ignition so the response to stretch could not be found. Lewis numbers calculated using data from Hirschfelder et al. [36].](/figures/table-1-laminar-flame-properties-na-denotes-flame-cellular-1eot36u7.webp)
Q2. What are the future works in this paper?
However, thermo-diffusive effects might also be expected to be important in light, lean flames ( e. g. hydrogen-air flames ) and further experimentation and theoretical studies are to be expected in this area.
Q3. How long does it take for the flame to reach the walls of the vessel?
It only takes a few milliseconds from ignition for the flames to reach the walls of this vessel, therefore flame progress must be captured at high speed.
Q4. What is the way to measure the velocity of a turbulent eddies?
high frequency (or small spatial resolution) measurements must be taken over sufficient time (or distance) for the turbulent eddies to be temporally or spatially correlated.
Q5. What was the purpose of the fans?
The fans were run during mixture preparation, both to ensure full mixing and to assist heat transfer from the vessel’s electrical heater.
Q6. Why was iso-octane chosen as the studied fuel?
Iso-octane was selected as the studied fuel due to its use as a surrogate gasoline in engine research and because its laminar burn rate changes dramatically with stretch rate between fuel lean and rich conditions, see Table 1 [5, 18].
Q7. What was the technique to use to capture flame progress?
When considering which technique to use to capture flame progress both experimental convenience and quality of information were considered, and high speed schlieren imaging was selected.
Q8. What is the advantage of schlieren photography?
Schlieren photography provides an easily identifiable leading edge in one plane; it is useful for high speed filming, as light is directed into the camera allowing short exposure times.
Q9. What is the advantage of high speed laser sheet imaging?
High speed laser sheet imaging has also been used in the vessel [12]; this has the advantage that the turbulent flame brush thickness can be determined and so flame radius unambiguously defined.
Q10. What was the speed of the fans used in turbulent tests?
In turbulent tests the fans were maintained at the set speed, to produce the desired rms turbulence intensity throughout the mixture preparation, ignition and combustion period.
Q11. What was the disadvantage of schlieren imaging for the vessel?
The disadvantage of this technique for the vessel adopted in the current work was that significant pressure rises could only be detected at large radii at which point the flame was nearly as large as the imaging areapermitted by the available window.
Q12. What made it difficult to compare the present data with those of other workers?
Uncertainty associated with the definition of the turbulent burning velocity, experimental technique and rig dependency rendered it problematic to compare the present data with those of other workers.
Q13. What is the effect of the Markstein number on the turbulence of the fuel?
A recent study performed in a similar type of vessel concluded that flames characterised with a negative Markstein number have a higher turbulent burning velocity than those with a positive Markstein number but that as turbulence was increased the differences between the two flames decreased [35].
Q14. Why was the Markstein length not quantifiable?
This was because the flames became cellular from ignition and, although a laminar burning velocity could be estimated based on the initial burn rate, the Markstein length could not be determined.
Q15. What is the effect of Lewis number on ut?
The shift in peak turbulent burning velocity to rich equivalence ratios for heavy hydrocarbons was demonstrated as far back as 1955, by Whol and Shore [34] on the basis of burner experiments; thus, the effect of Lewis number on ut has been demonstrated for a different geometry to that adopted in this study.
Q16. How was the flame brush thickness estimated?
Also the flame brush thickness could be estimated on the basis of laser sheet data for propane-air flames obtained in a earlier study [12].
Q17. How many turbulent burning velocity models were available in the literature?
Hence comparisons were made with data derived using five turbulent burningvelocity models and correlations available in the literature.