Experimental And Numerical Investigation On Ignition And Combustion Characteristics Of Chinese RP-3 Kerosene

Recently, some research topics on improving the efficiency of aero-engine and the utilization of aviation fuel oil have been paid extensively attention, such as, how to improve the efficiency of major combustion room, understand the combustion mechanism and reduce the negative impact on air of combustion.With the support of NSFC (51376133), a number of experiments on the ignition and combustion characteristic of RP-3 kerosene have been completed in this PhD thesis, and the experimental results have been mathematically explained. Details for research contents in this thesis are as follows:1. Recent achievements in the ignition and combustion characteristics and chemical reaction mechanisms of kerosenes and its surrogate fuels are reviewed systematically in this paper. Experimental studies of ignition and combustion characteristics about kerosenes have been accomplished in recent years abroad and they are employed for identifying the ignition delay times and laminar combustion velocities for mono-and bi-and multi-component surrogate fuels kinetic mechanisms for convenient jet fuels at different operating conditions. Reliable analysis and predictions by coupling the corresponding mechanisms into CFD models of engine combustor have provided an important basis for the flame control and flame stability. There is, however, a lack of the fundamental ignition and combustion characteristics of RP-3 kerosene in China. Thus, the fundamental combustion characteristics of RP-3 should be arranged and carried out immediately and it is important for the design and development of the primary combustor in an aeroengine in the future.2. Experimental studies of ignition and combustion characteristics of Chinese RP-3 kerosene have been c onducted in a shock tube and in a constant volume chamber. The initial pressure, the ignition temperature, the equivalence ratio and the fuel volume frations are analyzed on the influence on ignition characteristics of RP-3 kerosene and an Arrhenius correlations for the ignition delay time of the RP-3/02/Ar mixture about the above factors is fitted in the paper. It is found that RP-3 and JP-10 has the same impact factors of the volune fraction, pressure and equivalence ratio. The schlieren images of RP-3 kerosene combustion have been analyzed and essential parameters including the stretched and unstretched flame speed, Markstein length and laminar combustion velocity have been obtained from the experiment data. The results show that the equivalence ratio and the pressure of the mixture have more significant influence on the flame stability than the initial temperature.3. Based on the experimental data for the ignition delay times and combustion characteristics of RP-3 kerosene, a semi-detailed chemical reaction mechanism of RP-3 (includingl50 elements and 591 element reactions) has been presented. The semi-detailed chemical reaction mechanism has been validated by a comparison of the ignition delay time and the laminar combustion velocity from the forementioned ignition and combustion experiments of RP-3. Furthermore, a reduced mechanism (including 50 elements and 118 element reactions) has been obtained and validated from the semi-detailed and experiments by reaction path, the sensitive and reaction of produce analysis.4. The maximum operation condition in the primary combustor of a real aero-engine model has been numerically simulated by integrating the reduced mechanism into a CFD computational software. The flow and reaction kinetic characteristics of the combustion process as well as the formation of emissions and active species in the annular tube combustor were analyzed based on the simulation results. Recirculation zones have been observed in the front of the combustion tube and a stagnation zone appears next to it. They can ensure a stable and continuous flame combustion in the aero-engine. The gas speed is about 120m/s at the outlet of the combustion chamber along with the outlet shrinking and it has sufficient work capacity. The temperature at the front of the tube is about 1300K, it rises to the highest at the primary air inlet section and decreases along with more air inflow. The average temperature of 1265K at the outlet of the tube is close to the design condition of aviation engine and the radial distribution coefficient is in coincidence with the inlet pattern of a turbine.