空心旋转液体射流初始阶段特性的实验研究

以空心旋转射流的理论模型为基础［１］,通过实验对旋流喷嘴射流特性做进一步深入的研究,特别是实际射流形状的变化规律及喷嘴初始参数的变化规律．结果表明,旋流喷嘴的初始参数和空心射流内外表面压力差是决定射流形状的主要因素。     

New method for measuring diesel nozzle orif ice inlet structures based on synchrotron X-ray tomography

Spray behavior is regarded as one of the main factors influencing engine performances, fuel consumption and emissions for diesel engines. Under high injection pressure, diesel spray behaviors are extremely sensitive to the nozzle internal geometries, especially the geometric structures of orifice entrance. Based on the synchrotron radiation X-ray tomography technique, the 3D digital models of nozzle tips can be constructed. A new automatic method is presented to reveal the inlet structures according to these nozzle orifice models. The planes passing through the orifice axis are determined and used to cut the models, and then the corresponding cutting images are applied to measure the inlet chamfer radii around the orifice axis automatically. The orifices of a single-hole nozzle and an eight-hole nozzle are measured according to this method. The results show that this method can automatically measure the orifice inlet chamfer radii around the orifice axis with high precision. The obtained inlet chamfer radius shows the whole profile of the orifice entrance, which is a precise feedback for nozzle designing and manufacturing, and it also provides precise geometrical boundary conditions for the study of spray behaviors.     

基于机器视觉的发动机喷嘴检测系统的设计

以检测发动机喷嘴上几何尺寸为目的,设计了以TMS320DM642DSP为处理器,利用机器视觉技术进行检测的系统;通过CCD摄像机采集被测喷嘴的数字图像,在DSP中进行图像去噪、边缘检测、图像识别等图像处理过程,识别出被测尺寸并计算出值;阐述了该系统的工作原理和图像处理的算法,流程及实验结果。     

126Ce的EC/β+衰变

利用187 MeV的40Ca离子轰击同位素靶92Mo, 由熔合蒸发反应生成目标核126Ce。 藉助氦喷嘴快速带传输系统和X-X-t与X-γ-t符合测量, 首次建立了126Ce的EC/β+衰变纲图。 建议了可能属于126Ce一个高自旋同核异能态的衰变, 其β衰变后布居在与126La的高自旋同核异能态相关的低位能级区, 测定的半衰期是57(9) s。 也建议了可能属于126Ce基态的衰变, 其β衰变后布居在与126La的低自旋同核异能态相关的低位能级区,它的半衰期被测定为12(4) s。 但偶偶核126Ce存在高自旋同核异能态的物理原因还有待进一步探究。 Ce was produced by bombarding an enriched target of 92Mo with 187 MeV 40Ca beam and studiedby using a helium jet fast tape transport system in combination with X-γ and γ-γ coincidencemeasurements. An EC/β+ decay scheme of 126Ce was proposed for the first time. A group of low lying states associated with the low spin isomer in 126La feeding by β decay was possibly from the ground state EC/β+ decay of 126Ce with the measured half-life 12(4) s. Another group of low lying states associated with the high spin isomer in 126La feeding by β decay was possibly from a high spin isomer EC/β+ decay of 126Ce with the measured half-life 57(9) s. However, the physical reason for the existence of a high spin isomer in even-even nucleus 126Ce is still an open problem.     

提升管喷嘴进料段内气固两相流动的数值模拟

本文采用κ-ε-κ_p-κ_(pg)-θ模型,模拟了提升管喷嘴进料段内三维稠密气固交叉射流的复杂流动现象.结果表明,实验值和模拟值具有相同的变化趋势,再现了提升管喷嘴进料段内颗粒相的流动特点.     

工况对两相流引射制冷系统性能的影响

以R134a为工质,在不同工况条件下采用两段式喷嘴引射器对两相流引射制冷系统进行了实验研究,分析了冷凝温度和蒸发温度对R134a两相流引射制冷系统性能COP和引射比的影响,并与传统制冷循环系统进行了比较。实验结果表明:对于一定几何尺寸的引射器,系统COP随冷凝温度的升高而降低,随蒸发温度的升高而增大,在冷凝温度为40℃时,蒸发温度为1℃时,使用两段式喷嘴引射器时系统的COP要比传统蒸汽压缩循环的COP高22.7%,两相流引射制冷循环系统在较低的冷凝温度下更具有优势。     

高膨胀比有机工质向心透平气动优化研究

本文采用NURBS曲线参数化表达和控制几何型线,结合CFD数值实验,对膨胀比为8的有机工质向心透平进行气动优化研究。跨声速喷嘴叶型型线经气动优化后,喷嘴内处于顺压梯度的加速流动状态,喉部跨声速膨胀流动得到改善,流场最大Ma降低,全工况下的叶栅总压损失系数显著减小,跨声速工况下的级组效率明显提高。叶轮子午流道型线经优化后,流道宽度变化更均匀平滑,原动叶轮吸力面分离被消除,透平级组效率也有提高。     

气固两相对撞流颗粒运动特性分析

本文采用PIV两相同时测量方法,对低载荷气固两相双喷嘴对置撞击射流中的颗粒运动特性进行了研究。实验中轴向射流出口雷诺数为Re=14500,喷嘴内径为d=10 mm,喷嘴间距为L/d=12;颗粒相采用平均直径为dp=100μm的实心玻璃微珠,圆管加速段中的颗粒质量载荷控制为1%~4%。研究结果表明,低载荷下撞击射流中的颗粒间碰撞可忽略,颗粒浓度在喷嘴附近达到峰值;惯性使得颗粒轴向速度在穿入到反向射流前缓慢衰减,之后迅速减小;颗粒在撞击区形成高湍动区域,进而强化了颗粒相的混合效应。