Ignition Delay for Jet Propellant 10/Air and Jet Propellant 10/High-Energy Density Fuel/Air Mixtures

Abstract

Jet propellant 10 [(JP-10) or exotetrahydrodicyclopentadiene]is one of the leading candidate fuels for use in pulse detonation engine applications.As such, its ignition delay characteristics have been studied previously in very dilute mixtures at pressures from 1 to 9 atm and temperatures from 1300 to 1670 K. The ignition delay times are studied of JP-10/air and JP-10 blended with methylated PCU alkene dimer, nitronorbornane, dinitronorbornane, and ethylhexyl nitrate in air at pressures from 10 to 25 atm and temperatures from 1200 to 2500 K using a shock tube. Ignition delays were primarily measured using CH emission and secondarily using OH emission. Ignition delays were essentially insensitive to all of the additives tested. Additionally, ignition delays for dicyclopentadiene (a suspected intermediate in the combustion of JP-10) were also tested. Above 1500 K, multiple peaks in the CH emission were found. Further tests using OH emission indicate that the main peak in CH emission at these higher temperatures is probably due to reactions involved in the approach to equilibrium and give spuriously long ignition delay times.

JP-10 combustion studied with shock tube experiments and modeled with automatic reaction mechanism generation

“…The Davidson and Mikolaitis datasets used the peak CH ⁄ emission as the indicator of ignition, while both Colket and Wang experiments used initial rise onsets of the CH ⁄ emission, leading to faster measured ignition times. Mikolaitis and coworkers [9] found that at intermediate temperatures, two emission peaks for ignition delay were present. The first peak ignition delays from the CH emission were recommended by the authors the true indicator of ignition and are compared with the model predictions here.…”

“…Temperature range (K) Pressure range (atm) Equivalence ratios (U) Bath gas Ignition delay metric Colket and Spadaccini [8] 1250-1500 3-7 0.5-1.5 Ar Initial rise onset in OH ⁄ emission Davidson et al [7] 1300-1700 1-6 0.5-2.0 Ar Peak CH ⁄ emission Mikolaitis et al [9] 1200-2000 10-25 1.0 N 2 Peak CH ⁄ emission Wang et al [10] 1000-2100 1.5-5. [41] and found that the OH concentration is primarily sensitive to C 2 oxidation reactions.…”

“…Four experimental datasets for JP-10 ignition delay can be found in literature [7][8][9][10]. The summary of the experimental conditions and ignition delay measurement metrics can be found in Table 3.…”

“…Davidson et al [7] reported ignition delay times and OH concentration time histories behind reflected shock waves in the temperature range 1300-1700 K with pressures ranging from 1-6 atm. Colket and Spadaccini [8] reported ignition delays in the temperature range 1250-1500 K. Mikolaitis et al [9] conducted ignition delay measurements at higher temperatures up to 2000 K and higher pressures of 10-25 atm. They also found that JP-10's ignition delays were generally insensitive to fuel additives.…”

A DFT study on the thermal cracking of JP-10

“…Although studies [1][2][3][4][5][6][7][8][9][10][11] have been conducted to investigate the physical properties and catalytic cracking of JP-10 at various temperatures and pressures by means of spectroscopic, gas chromatographic, and mass spectrometric analyses, the high-temperature thermal decomposition chemistry of JP-10 is still not well understood.…”