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The ever increasing consumption of non-renewable fossil fuels for global economic development leads to serious energy crisis and environmental pollution. Consequently, new alternative fuels and high-efficiency combustion are required to aid the sustainable development of human society. The present paper took the RP-3 aviation kerosene and coal-to-liquid synthetic aviation fuel (manufactured through the Fischer Tropsch process., FT) for object, and experimentally investigated the influences of pressure, inlet temperature and equivalence ratio on the productions of NOx and CO in a jet stirred combustion reactor. The tests were performed under the pressures of 2bar and 3bar, and inlet air temperatures of 550K and 650K, respectively. The equivalence ratio ranged from 0.5 to 1.2. The mean residence time was approximately 8ms. Probe sampling followed by on-line emissions analyzer permitted to measure the concentration of the products. The experimental results show that these two fuels obey the same law with the variations of pressures, inlet temperatures and equivalence ratios. The NOx production increases with the pressure and inlet temperature increasing. The CO decreases with the pressure increasing, while slightly increases with the inlet temperature increasing. Numerical simulations were also performed to investigate the combustion products of these two fuels in the jet stirred combustion reactor. Two PSRs were introduced to simulate the jet flame region and post flame in the recirculation region, respectively. The combustion products of second PSR (PSR2) agreed well with the experimental results by regulating the volume ratio of first PSR (PSR1). Based on the reaction pathway analysis of NO production in present state, it is considered that for these two fuels the NOx production is led by the thermal NO above the equivalence ratio of 0.65, while by the N2O at lower equivalence ratios. With the application of the present alternative fuel and its reaction mechanism, the experimental results of aviation kerosene and Coal-to-Liquid synthetic aviation fuel can be predicted well within a certain state, which requires a further verification in a wider range. Furthermore, the numerical results show that the NO release is insensitive to the reaction components within present experimental states.

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The Non-Uniform Rational B-spline (NURBS) surface not only has the characteristics of the rational Bézier surface, but also has changeable knot vectors and weights, which can express the quadric surface accurately. In this paper, we investigated new bounds of the first- and second-order partial derivatives of NURBS surfaces. A pilot study was performed using inequality theorems and degree reduction of B-spline basis functions. Theoretical analysis provides simple forms of the new bounds. Numerical examples are performed to illustrate that our method has sharper bounds than the existing ones.