| 1. | Theory of the self - excited oscillation pulsed jet nozzle
自激振荡脉冲射流喷嘴的理论分析 |
| 2. | This dissertation is devoted to the investigation of the influence of self - excited oscillation jet on heat transfer enhancement
本课题将helmholtz共振腔所产生的自激振荡脉冲射流引入换热器以实现强化换热。 |
| 3. | Secondly , the helmholtz oscillator was designed . based on the flow network theory , the expression of intrinsic frequency was deduced . the main parameter of helmholtz oscillator was calculated
对于同一结构的helmholtz共振腔，水力参数不同，所产生的自激振荡脉冲射流的强弱也不相同。 |
| 4. | The theoretical and experimental results show that the efficiency of transmission of energy and mass to use pulsed jet is greatly raised , compared with steady jet , in the same device of liquid jet pump
结果表明，在相同的液体射流泵装置上，采用脉冲射流比恒定射流的传能及传质效率有较大的提高。 |
| 5. | Finally , the experiment was performed in order to exam the effect . the pulsating liquid flows through a single pipe heated electrically . the heat transfer coefficients were measured under different conditions
将helmholtz共振腔产生的自激振荡脉冲射流引入换热器后，当自激振荡的强度达到一定程度后，可以强化换热。 |
| 6. | This paper introduces several kinds of principles of pulse jet technology , discusses their advantages and disadvantages , sums up the rules of pulse jet beating the target and analyses its stress characteristics
摘要本文概括介绍了几种脉冲射流技术的原理，探讨了各自的优势与不足，归纳了脉冲射流打击靶体的规律，并分析总结了脉冲射流的应力特点。 |
| 7. | When the pulsating jet was introduced in the heat exchanger , pulsating flow leads to the formation of an amount of vortices near the tube wall . the boundary layer was destroyed and the mixing of liquid was improved , so heat transfer enhancement was achieved
将自激振荡脉冲射流引入换热器后，流体的脉动导致了壁面处旋涡的大量生成，增加了流体的掺混，实现强化换热的目的。 |
| 8. | Firstly , the mechanism of self - excited oscillation was introduced . when the water jets from the inlet nozzle flows into the chamber , the momentum exchange between the jet and the liquid in the chamber occurs , thus to form an unstable shearing layer with certain thickness
这是一种崭新的强化换热技术，流体脉动能够造成换热器全程的换热强化，而且自激振荡脉冲射流强化换热技术本身是一种无功强化的方法，无需输入外部能量来产生扰动。 |
| 9. | The comparison of the calculation formula for unsteady jet flow with that of steady jet flow demonstrates that the pulse frequency is the main factor influencing the velocity coefficients 2 and 5 , and the relationship between the velocity coefficients of pulsed jet flow and steady jet flow was revealed
通过与恒定射流的流速系数计算式对比，阐明了脉冲频率是影响2和5的主要因素，沟通了脉冲射流与恒定射流流速系数之间的关系。 |
| 10. | The shearing layer is carried by the jet and the eddy is formed because of the instability and selective amplification of shearing layer which will propagate to the downstream . as the eddy impacts the impinging wall , a wave of pressure disturbance with certain frequency is induced . this wave then propagates to the upstream with high speed , and results in the overlap and amplification of the waves when the frequencies of them are close with each other
当前喷嘴流束中的不稳定扰动波在穿过腔内的剪切层时，剪切层对其有选择放大作用，形成涡环结构，剪切流动中涡环与碰撞壁撞击，在碰撞区域产生压力扰动波并向上游反射，在上游剪切层分离处诱发新的扰动的产生，当新扰动与原扰动匹配时，射流上游就被不断地受到周期性激励，腔内就产生流体自激振荡并在后喷嘴出口形成脉冲射流。 |
