火箭推进

为清楚阐明3D打印技术是否可应用于加工火箭发动机的关键部件——喷嘴,及加工方式会对推进剂的流动雾化产生何种影响,对相同结构的机械加工喷嘴与3D打印喷嘴的喷雾特性进行了冷态试验对比研究。基于背景光成像技术采用高速相机获得瞬态的喷雾图像,以及激光散射技术采用马尔文测量液滴粒径尺寸分布。研究发现:机械加工喷嘴同轴度普遍较差,喷嘴重复性较低,喷雾存在偏斜、分散等喷雾空间分布不均问题; 3D打印喷嘴表面粗糙度较高,使得喷嘴流量系数比设计值低3%左右; 在喷嘴同轴度较好的前提下,加工方式对雾化锥角及雾化粒径影响较小。

In order to clarify whether 3D printing technology can be applied to machine the injector which is a critical component of the rocket engine, and how the processing method affects the flow and atomization characteristics, the cold spray experiments were conducted using the 3D printing and machined injectors with the same structure. A back-lighting photography technique has been employed to capture the instantaneous spray images with a high speed camera. The droplet size distribution was measured using Malvern based on the laser scattering technique. The results show that the coaxiality and repeatability of the machined injectors is generally poor, and the spray has the problem of uneven spatial distribution such as deflection and dispersion. While for the 3D printing injectors, the discharge coefficient is lower than the designed value by 3% due to its higher roughness. On the premise of the better injector coaxiality, the processing method has less influence on the spray angle and diameter.

引言
1 试验方法
2 结果和讨论
3 结论

图1 同轴三组元喷嘴内喷嘴示意图<br/>Fig.1 Schematic of the coaxial tri-propellant injector

图1 同轴三组元喷嘴内喷嘴示意图
Fig.1 Schematic of the coaxial tri-propellant injector

表1 机械加工与3D打印技术对比<br/>Tab.1 Comparison of 3D printing and machined technique

表1 机械加工与3D打印技术对比
Tab.1 Comparison of 3D printing and machined technique

表2 同轴三组元喷嘴主要结构尺寸<br/>Tab.2 Key geometrical parameters of the coaxial tri-propellant injector

表2 同轴三组元喷嘴主要结构尺寸
Tab.2 Key geometrical parameters of the coaxial tri-propellant injector

图2 同轴三组元喷嘴冷试夹具示意图<br/>Fig.2 Schematic of the coaxial tri-propellant injector with cold test fixture

图2 同轴三组元喷嘴冷试夹具示意图
Fig.2 Schematic of the coaxial tri-propellant injector with cold test fixture

图3 雾化试验系统示意图<br/>Fig.3 Schematic diagram of atomization test system

图3 雾化试验系统示意图
Fig.3 Schematic diagram of atomization test system

表3 试验工况<br/>Tab.3 Experimental conditions and parameters 单位:MPa

表3 试验工况
Tab.3 Experimental conditions and parameters 单位:MPa

图4 Malvern测量系统<br/>Fig.4 Malvern measuring system

图4 Malvern测量系统
Fig.4 Malvern measuring system

图5 喷雾锥角获取方法<br/>Fig.5 Image processing method for obtaining the spray angle

图5 喷雾锥角获取方法
Fig.5 Image processing method for obtaining the spray angle

图6 Ma-I和3D-I的同轴度对比<br/>Fig.6 Coaxiality comparison of Ma-I and 3D-I

图6 Ma-I和3D-I的同轴度对比
Fig.6 Coaxiality comparison of Ma-I and 3D-I

图7 喷嘴出口实物图
Fig.7 Injectors outlet

表4 Ma-I与3D-I试验所得流量系数对比<br/>Tab.4 Comparison of the tested discharge coefficient for Ma-I and 3D-I

表4 Ma-I与3D-I试验所得流量系数对比
Tab.4 Comparison of the tested discharge coefficient for Ma-I and 3D-I

表5 输入参数
Tab.5 Input parameters

图8 Ma-I与3D-I流量系数随气液比的变化关系<br/>Fig.8 Discharge coefficient with respect to GLR for Ma-I and 3D-I

图8 Ma-I与3D-I流量系数随气液比的变化关系
Fig.8 Discharge coefficient with respect to GLR for Ma-I and 3D-I

图9 Ma-I与3D-I的瞬态喷雾形态(Δpl=1.2 MPa,Δpo=1 MPa,Δpa=0.8 MPa)<br/>Fig.9 Instantaneous spray patterns of Ma-I and 3D-I

图9 Ma-I与3D-I的瞬态喷雾形态(Δpl=1.2 MPa,Δpo=1 MPa,Δpa=0.8 MPa)
Fig.9 Instantaneous spray patterns of Ma-I and 3D-I

图10 Ma-I与3D-I的喷雾锥角随液体雷诺数的变化关系<br/>Fig.10 Spray angle with the liquid Reynolds number for Ma-I and 3D-I

图10 Ma-I与3D-I的喷雾锥角随液体雷诺数的变化关系
Fig.10 Spray angle with the liquid Reynolds number for Ma-I and 3D-I

图11 Ma-I与3D-I的SMD随液体雷诺数的变化关系<br/>Fig.11 SMD with respect to the liquid Reynolds number for Ma-I and 3D-I

图11 Ma-I与3D-I的SMD随液体雷诺数的变化关系
Fig.11 SMD with respect to the liquid Reynolds number for Ma-I and 3D-I

备注

引言

1 试验方法

2 结果和讨论

3 结论

期刊信息