The Observation of the Spray Phenomena of Unlike-doublet Impinging Jets

• Main Authors: Wei-Cheng Chun, 陳威丞
• Other Authors: Hsiao-Feng Yuan
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/03485087015629750667

碩士 === 國立成功大學 === 航空太空工程學系 === 89 === By image analyzing technique coupled with statistical analysis, this thesis studied the impinging spray phenomena based on 5-lbf MMH/NTO thruster operation specifications. Both like-doublet and unlike-doublet experiments were performed. Like-doublet experiments used water-based solutions as working fluid, while unlike-doublet used chloroform-based solutions to simulate the physical properties (density, viscosity and surface tension) of MMH and NTO, respectively. The total mass flow rate was controlled at a constant value (~8.00 g/s). The mass flow rate ratios of oxidizer to fuel (O/F) for like-doublet were varied between 1.0 to 1.3, and 1.0~1.6 for unlike-doublet experiments. The diameter of the orifices for designed injector was 0.3mm, and the impinging angle used were 60o and 90o. The observation focused on droplet distribution, shift angle and spray angle of the spray fan. The results show: （1） For like-doublet impingement, when O/F=1.0, droplets have a uniform space distribution; while for O/F>1.1, droplets were observably more concentrated at the central axis of the spray fan. For unlike-doublet impingement, when O/F>1.2 for 60o impinging angle and O/F>1.3 for 90o impinging angle, droplets distribution were also observably more concentrated at the central axis. （2） For like-doublet impingement, when O/F=1.0(momentum ratio =1.0), the spray fan was symmetric distributed to the vertical central axis of the two orifices, however, when O/F>1.0, the spray fans were asymmetric to the vertical central axis of the two orifices and shifted to the lower momentum side of the two orifices. For unlike-doublet impingement, when O/F was equal and larger than 1.2(momentum ratio was equal and larger than 1.0), the spray fans were also shifted. Comparing to the like- doublet, the phenomena of spray shifting for unlike-doublet impingement at momentum ratio of 1.0 showed that the physical properties of working fluid also play an important role in the shifting phenomena of the spray fan. （3） For like-doublet and unlike-doublet impingements, the shift angles increased with increasing momentum ratio as well as the horizontal momentum differences of the impinging jets. However, with a larger impinging angle, the increase of the shift angle with the horizontal momentum difference was more apparent. （4） For like-doublet and unlike-doublet impingements, maximum values of spray angles were observed while the O/F ratios were varying. For like-doublet impingement, a maximum front view spray angle existed at O/F=1.1(momentum ratio=1.21), and a maximum side view spray angle existed at O/F=1.2 (momentum ratio=1.42), however, it matched with the onset of maximum summation of the horizontal momentums of the two jets. For unlike-doublet impingement, the maximum front view spray angles existed at O/F=1.2 (momentum ratio was about 1.0) for 60o impingement, and O/F =1.0~1.2(momentum ratio=0.66~0.96) for 90o impingement, respectively. For the impinging angle studied, the onset of the maximum side view spray angle was always at O/F=1.2, that is, the momentum ratio was about 1.0.