Q2. What was the effect of the initial explosion on the dynamic pressures?
In the case of low methane concentration (i.e 1.25% and 2.5%), the reading of dynamic pressures were over driven by the initial explosion in the firstsection.
Q3. How much methane was exempted from the flame intensity signal?
The flame intensity signal of the first section ranged between 1.5 V to 3 V. Regardless, the methane concentration in the RS, exempting the 9.5% scenario, caused the flame intensity signal in the first section to reach about 4.5 V.
Q4. What is the purpose of the flame velocity record?
A detailed record of methane flame deflagration velocity is not only required to determine the pressure impulse and explosion development, but also to design an effective flame mitigation system.
Q5. How much pressure did the flame velocity at 5% methane concentration increase?
The flame velocity at 5% methane concentration, however, when increasing the RS length from 12 m to 25 m, significantly accelerated the flame velocity from 70 m.s-1 to about 83 m.s-1.
Q6. What was the maximum dynamic pressure for a 12 m RS length?
The maximum dynamic pressure recorded was 2.56 bar at a 9.5% concentration for a 12 m RS length and the maximum side on pressure was higher than the side on pressure in all the other results.
Q7. How did the pressure wave behave at the 3 m RS length?
the pressure wave declined gradually to 0.4 bar, where the pressure wave profile behaved in a typical way to the observed methane explosion at the 3 m RS length (see Figure 9).
Q8. What is the definition of the flame velocity?
The flame velocity helps to estimate the distance and time required between the flame detectors and the location where the flame mitigation acts.
Q9. What was the stoichiometric explosion characteristics of the methane-air?
The explosion characteristics, pressure wave and flame velocities were investigated for a wide range of methane-air mixtures (1.25%, 2.5%, 5%, 7.5%, 10% and 15%).
Q10. What was the effect of the position of the ignitor on the flame speed and pressure?
They also noticed that the position of the ignitor plays an important role on the flame speed and pressure profile, where the maximum pressure was recorded when the ignitors were in the middle of the tube.
Q11. What was the maximum pressure wave velocity for the methane stoichiometric?
The maximum pressure wave velocity was 310 m.s-1 for methane stoichiometric concentration at 9.5 m, and the minimum pressure wave velocity was 25 m.s-1 at 5% methane concentration for the 3 m RS (see Figure 10).
Q12. What is the difference between the pressure wave velocity and the flame velocity in the early stage?
As the flame velocity in the early stage is relatively low due to the low burning rate, a slow pressure wave velocity was generated.
Q13. What was the size of the detonation tube used in this study?
The detonation tube used in this study consisted of eleven sections with a diameter of 0.5 m, a total length of 30 m, and a 6 m silencer attached at the end of the tube to reduce the noise of the explosions (see Figure 1).
Q14. What was the flow rate for the first and second circulation blowers?
Each circulation system consisted of a blower (the volumetric flow rates for the first and second circulation blowers were 720 litre/min and 1900 litre/min, respectively).
Q15. At what concentration was the flame velocity at the stoichiometric methane?
At a stoichiometric methane concentration (see Figure 12 (a)), the peak velocity was achieved at 17.5 m before the flame velocity began to decline.