直射喷嘴结构对超低温氮气射流温度和速度的影响

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中文摘要：液氮冷却低温切削是实现钛合金等难加工材料的绿色、高质量加工的有效手段之一。为实现面向超低温氮气射流过程温-速控制的喷嘴结构优选，采用数值模拟结合实验研究的方法，探析锥直型喷嘴入口直径D、出口直径d、收缩角α0以及长径比l/d对出口射流场温-速分布的影响规律。研究结果表明:存在一核心结构场使得场内射流速度和温度与喷嘴出口处的一致，而核心结构场外速度衰减幅值与温升幅值随出口直径d增加而减小。在实验条件下，当d从2。0 mm增至4。0 mm时，射流速度衰减幅值自386。3 m/s降至40。1 m/s，射流温升幅值自92。7 K降至41。1 K;射流速度核心区长度sn1和射流温度核心区长度sn2与d呈线性正相关，且sn1的变化率为sn2变化率的1。4倍;相较于l/d，d对出口轴心射流速度um的影响更显著。随着d从2。0 mm增至4。0 mm，um降低了74。9%;随着长径比l/d从1增至4，um增加了3。2%，表明减小喷嘴出口直径和增大长径比有利于提高锥直型出口射速。

外文标题：Influence of direct injection nozzle structure on jet temperature and velocity in nitrogen at low temperature

外文摘要：Liquid nitrogen cooling cryogenic cutting is one of the most effective means to realize green machining of titanium alloy and other difficult-to-machine materials.In order to realize the preferred nozzle structure for the temperature-velocity control of the low-temperature nitrogen jet process,numerical simulation combined with experimental research was used to analyze the influence of the conical straight nozzle inlet diameter D,outlet diameter d,contraction angle α0,and the length-to-diameter ratio l/d on the temperature-velocity distribution of the outlet jet field.The results show that the existence of a core structure field makes the velocity and temperature consistent with that of the nozzle exit,and the magnitudes of velocity decay and temperature rise outside the core structure field decrease with the increase of the exit diameter d.Under the experimental conditions,when d increases from 2.0 mm to 4.0 mm,the jet velocity decay amplitude decreases from 386.3 m/s to 40.1 m/s,and the jet temperature rise amplitude decreases from 92.7 K to 41.1 K.The core area length of the jet velocity sn1 and the core area length of the jet temperature sn2 are positively correlated with d linearly,and the rate of change of sn1 is 1.4 times as much as that of sn2.d and l/d have effects on the exit axial jet velocity,with the effect of d being more significant.As d increases from 2.0 mm to 4.0 mm,um decreases by 74.9%.As the length-to-diameter ratio l/d increases from 1 to 4,um increases by 3.2%.It is indicated that decreasing d and increasing l/d can increase the exit jet velocity.

外文关键词：

cryogenic nitrogen jetdirect injection nozzle structurejet core lengthaxis jet velocitynumerical simulation

作者：

何奇汭、杨东

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作者单位：

安徽大学机械工程系,安徽合肥,230601

关键词：

超低温氮气射流直射喷嘴结构射流核心区长度轴心射流速度数值模拟

基金：

国家自然科学基金资助项目安徽省高等学校自然科学研究重大项目National Natural Science Foundation of ChinaNatural Science Research Programs at Higher Education Institutions of Anhui Province

项目编号：

520050022023AH040010

出版年：

2024

DOI：

10.11817/j.issn.1672-7207.2024.07.007

中南大学学报(自然科学版)

中南大学

中南大学学报(自然科学版)

CSTPCD北大核心

影响因子：0.938

ISSN：1672-7207

年,卷(期)：2024.55(7)