Experimental Study on the Deflagration Characteristics of the Liquid Propellant Spray Electrical Ignition and the Simplified Model Calculation
The liquid propellant atomization experimental apparatus, single pulse discharge device and the AC (alternating current) sequence discharge device have been designed to explore the electrical ignition method of HANbased liquid propellant. By using of high speed camera system, the electrical ignition experiment study of the HAN-based liquid propellant LP1846 under different injection pressure has been conducted. The results indicate that: the spray can be ignited instantly by single pulse discharge method as the Sauter mean diameter of the LP1846 droplets is in the region of 10~20 μm, but there is deflagration ability; stable ignition can be got by alternating current pulse discharge method as SMD of LP1846 droplets is in the region of 40~50 μm . Based on the experiment, the simplified model of LP1846 atomization pulse discharge ignition delay time has been proposed. The numerical results coincide well with the experimental results.
Combustion Characteristics of Energetic HAN/Methanol-Based Monopropellants
The pressure dependence of burning rate for two HAN/Methanol-based liquid monopropellants is studied between 0.74 and 7.3 MPa. The less energetic formulation, HAN269MEO15, is found to exhibit different combustion characteristics above 1.21 MPa and below 1.14 MPa. Changed characteristics include a sharp increase in the burning rate, and a drastic change in the combustion behavior. HAN284MEO17 also exhibits two distinct combustion behaviors, however the transition occurs around 2.9 MPa. The appearance of a flame, a pronounced increase in the burning rate slope, and a characteristic change of the temperature-time trace of the reaction zone all indicate a change in the burning mechanism at this pressure. Surprisingly, the burning rate of the more energetic formula is lower than the less energetic one. Temperature measurements of the reaction zones of both propellants indicate that the boiling points of water and methanol play an important role in the combustion processes. Since the measured reaction zone temperatures are significantly less than calculated adiabatic flame temperatures, it is likely that the propellants are not reacting to their full potential in the near field.
A kinetic study of the pyrolysis of methanol using shock tube and computer simulation techniques
Abstract The reaction of methanol with oxygen is studied by shock tube techniques at 1800–2800 K in five gas mixtures ranging in composition from lean to rich. Measurements are made by laser schlieren densitometry and dynamic mass spectrometry. At high temperatures, the shock-wave-initiated reaction consists qualitatively of two steps. In the first step, methanol decomposes with very little consumption of oxygen, forming H 2 , radicals, and some stable products (CO and H 2 O). In the second step, the H 2 O 2 reaction takes place accompanied, especially in lean mixtures, by the oxidation of CO. At the lower end of the temperature range of the measurements, the two steps tend to merge. A comprehensive mechanism based on literature data and the present experiments is proposed and used to interpret the experimental results by detailed computer simulation. Sensitivity analysis is used to identify a set of seven elementary reactions to whose rate constants the results are most sensitive: 1. CH 3 OH + M → CH 3 + OH + M, (1) 2. CH 3 OH + M → CH 2 OH + H + M, (1a) 3. CH 3 OH + OH → CH 2 OH + H 2 O, (3) 4. CH 3 O + O → CH 2 O + H, (18) 5. CHO + M → CO + H + M, (31) 6. CHO + H → CO + H 2 , (32) 7. H + O 2 → OH + O. (40) New values of the rate constants of these reactions are suggested by systematically fitting the results of these experiments and of a similar study of methanol pyrolysis. The fitting procedure makes use of sensitivity analysis and the estimated accuracy of the literature values of the rate constants in the mechanism.