Study on atomization and combustion characteristics of -- Fang, Xin-xin; Shen, Chi-bing -- Acta Astronautica, 136, pages 369-379, 2017 jul -- Elsevier -- 10.1016_j.actaastro.2017.03

X.-x. Fang, C.-b. Shen Acta Astronautica 136 (2017) 369–379
Fig. 18. Streamline for different L*.
Fig. 21. Schematic configuration for two different pintle engines in three-dimensional
numerical simulation.
Fig. 19. Combustor pressure for different L*.
Fig. 22. Temperature (K) field for two different pintle engines.
Fig. 20. Schematic configuration for improved pintle engines.
of cells. Fig. 18 shows the streamline for different L*. The size of the
two recirculation zones changes little.
Fig. 19 shows the combustor pressure for different L*. It can be seen
that the larger L* is, the higher the combustion pressure of the pintle
engines is. But increase of the combustor pressure is little while L* is
larger than 1.2 m. It has been analyzed in Section 5.1 that the bigger
Ls/
Dp is, the smaller the effective characteristic length of the combustor
is. When the characteristic length is small, the time for mixing and
reaction is less. The biggest particle residence time is 2.33 ms, 3.05 ms,
3.27 ms and 3.36 ms when the characteristic lengths are 0.8 m, 1.0 m,
1.2 m and 1.4 m respectively. Bigger particle residence time means the
Fig. 23. Mole fraction distribution of gaseous methane.
oxygen can react with the methane more sufficiently. Thus bigger
characteristic length means higher combustion efficiency and combustor
pressure (see in Fig. 19). On the other hand, larger values of L*
mean heavier pintle engines. So the value of L* is a tradeoff between the
combustion efficiency, weight and cooling of the wall of the pinle
engines.
5.4. Improvement of pintle structure
From the two-dimensional numerical simulation results, the combustion
efficiency of the pintle engines is low (around 0.96). It is
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