The Mixing Phenomena of Impinging Jets

• Main Authors: Yi-Quan Zhung, 鍾易全
• Other Authors: Tony Yuan
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/44731820712693455823

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 92 === 　　This thesis studied the doublet impinging spray phenomena with fluids simulating the physical properties of NTO and MMH. Photographic images of front and side views as well as PLIF cross image of spray cone were observed. The two-dimensional probability distributions of the mass of impinging jets were determined by simple statistical analysis.The total mass flow rate was fixed as 7.96g/s to meet the operational condition of a 5-lbf MMH/NTO thruster. The orifice diameter of the injectors were 0.3mm and the impinging angle was set to be 60°. The experimental mass flow rate ratios of oxidizer to fuel (O/F) were varied between 1.0 and 1.6. Several conclusions were drawn from the observations: (1) By assuming the downstream mass distribution of the impinging jets was self-preserved and modeled by Weibull distribution function, the planar mass distribution crossing the spray cone were　successfully determined from the photographs of the front- and side-view the spray fan. However,　this technique is inadequate when the shape of the spray cone was concaved, that is, the momentum ratio of the impinging jets is away from unity. (2) Gray level analysis of the image from planar laser-induced light scattering observations were used to directly measure the mass distribution crossing the spray cone. It could be seen that the distribution was strongly affected by the ratio of jets’momenta. When the ratio of momenta increased, the distribution of spray moved toward the lower momentum injector, the same conclusion drawn from the analysis of the side-and front-view of the spray fan. (3) To compare the observations of unlike-doublet to like-doublet impingements, it showed that the mass distribution of impinging jets were not only affected by the jet’s momentum ratio but also affected by the jet’s physical properties as well. (4) PLIF technique was used to monitor the mass distribution of individual jet. The distributions of local mixture ratios as well as the estimated local temperatures were determined by assuming infinitely fast reaction. The results indicated that the peak flame temperature was not noticeably changed with O/F. The present study confirmed the adequacy of using PLIF technique in spray observation, more detailed determination of temperature and mixture ratio distributions required further studies with a higher energy pulse laser.