Two hydrophobic imidazolylidene-cyanoborane complexes were prepared by the introduction of{BH2 CN} into the molecular formula via treatment of imidazolium iodide and Na BH3 CN avoiding literature’s tedious and hazard...Two hydrophobic imidazolylidene-cyanoborane complexes were prepared by the introduction of{BH2 CN} into the molecular formula via treatment of imidazolium iodide and Na BH3 CN avoiding literature’s tedious and hazardous procedures. These two complexes were fully characterized using IR spectroscopy,1 H NMR and13C NMR spectroscopy and high-resolution mass spectrometer. The X-Ray structure of NHC-1 has been determined. NHC-2 was proved to be hypergolic with WFNA and displayed the attractive properties such as water immiscibility, wide liquid range（Tg= -22C）, short ignition delay time（13 ms）, high density（0.98 g/cm3）, good density impulse（r Isp, 347 s g cm-3）, showing the promising application potential as a fuel and an efficient fuel additive.展开更多
Turbulent two-phase reacting flow in the chamber of LOX/RP-1 bipropellant liquid rocket engine is numerically investigated in this paper. The predicted pressure and mean axial velocity are qualitatively consistent wit...Turbulent two-phase reacting flow in the chamber of LOX/RP-1 bipropellant liquid rocket engine is numerically investigated in this paper. The predicted pressure and mean axial velocity are qualitatively consistent with the experimental measurements. The self-excited pressure oscillations are obtained without any disturbance introduced through the initial and boundary conditions. It is found that amount of abrupt pressure peaks appear frequently and stochastically in the head regions of the chamber, which are the important sources to drive and strengthen combustion instability. Such abrupt pressures are induced by local constant volume combustion, because local combustible gas mixtures with high temperature are formed and burnt out suddenly due to some fuel droplets reaching their critical state in a rich oxygen surrounding. A third Damkhler number is defined as the ratio of the characteristic time of a chemical reaction to the characteristic time of a pressure wave expansion to measure the relative intensity of acoustic propagation and combustion process in thrusters. The analysis of the third Damkhler number distributions in the whole thrust chamber shows that local constant volume combustion happens in the head regions, while constant pressure combustion presents in the downstream regions. It is found that the combustion instability occurs in the head regions within about 30 mm from the thruster head.展开更多
基金the financial support from the National Natural Science Foundation of China (Nos. 21372027, 21376252)
文摘Two hydrophobic imidazolylidene-cyanoborane complexes were prepared by the introduction of{BH2 CN} into the molecular formula via treatment of imidazolium iodide and Na BH3 CN avoiding literature’s tedious and hazardous procedures. These two complexes were fully characterized using IR spectroscopy,1 H NMR and13C NMR spectroscopy and high-resolution mass spectrometer. The X-Ray structure of NHC-1 has been determined. NHC-2 was proved to be hypergolic with WFNA and displayed the attractive properties such as water immiscibility, wide liquid range（Tg= -22C）, short ignition delay time（13 ms）, high density（0.98 g/cm3）, good density impulse（r Isp, 347 s g cm-3）, showing the promising application potential as a fuel and an efficient fuel additive.
基金supported by the National Natural Science Foundation of China(Grant No.50706021)
文摘Turbulent two-phase reacting flow in the chamber of LOX/RP-1 bipropellant liquid rocket engine is numerically investigated in this paper. The predicted pressure and mean axial velocity are qualitatively consistent with the experimental measurements. The self-excited pressure oscillations are obtained without any disturbance introduced through the initial and boundary conditions. It is found that amount of abrupt pressure peaks appear frequently and stochastically in the head regions of the chamber, which are the important sources to drive and strengthen combustion instability. Such abrupt pressures are induced by local constant volume combustion, because local combustible gas mixtures with high temperature are formed and burnt out suddenly due to some fuel droplets reaching their critical state in a rich oxygen surrounding. A third Damkhler number is defined as the ratio of the characteristic time of a chemical reaction to the characteristic time of a pressure wave expansion to measure the relative intensity of acoustic propagation and combustion process in thrusters. The analysis of the third Damkhler number distributions in the whole thrust chamber shows that local constant volume combustion happens in the head regions, while constant pressure combustion presents in the downstream regions. It is found that the combustion instability occurs in the head regions within about 30 mm from the thruster head.
