幂律流体液膜射流破碎机理的实验研究-动力机械及工程专业毕业论文.docx

ABSTRACT The breakup mechanism of the liquid jet is a classical fluid mechanics problem, also it has guiding significance for technical application. The liquid sheet formed by impinging jets has been widely used in the combustion system of liquid rocket engine, for its simple construction, good atomization, low cost and high reliability. Power-law fluid is a new kind of propellant possessing the advantages of the solid and liquid propellant. In order to control the jet breakup and optimize the combustion progress, this paper studies the breakup progress and characteristic of the liquid sheet formed by the impinging jets. An optical test system was designed and built, including the liquid pressured and transporting system, impinging liquid sheet system, pulse control system, High-speed imaging system, phase Doppler analyzer and waste recovery system. The optical shadow picture can be obtained by using the High-speed camera, from which the breakup regime and the breakup characteristic (like the breakup length, surface wave length, spray cone angle and sheet characteristic) was extracted. By using the phase Doppler analyzer, the 3-D velocity of droplet and particle size and distribution were measured. Results indicate that the species of breakup regime are different with using different Power-law fluids. The sheet length-width ratio and the max length-max width increase with increasing the viscosity. Thickness of the sheet edge is similar to the jet diameter. When increasing the jet velocity, the surface wave length decreases and the spray cone angle increases gradually and tends to the maximum angle less than the impinging angle. The transformation law of the breakup length is related to the rheological behavior, when increasing the jet velocity, 0.15wt% and 0.25wt% Power-law fluids show twin peaks pattern, while 0.35wt% and 0.5wt% Power-law fluid is single peak. Once entering the turbulent flow, the breakup length decreases with increasing the jet velocity. When incr