Investigation of rapid evaporation in a nozzle

喷嘴内快速蒸发的研究

• 批准号: 138424-2006
• 负责人: McCahan, Susan
• 金额: $ 1.2万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=391512
• 关键词: Investigation; rapid; evaporation; nozzle

The proposed research is an experimental program to assess rapid evaporation as a means for improving atomization of fuel sprays. The work will characterize nucleation processes in pure liquids and liquids with additives.  Presently there are a number of competing models to explain the rapid phase change witnessed in flashing sprays, BLEVE's (Boiling Liquid Evaporating Vapour Explosions), steam explosions, and other explosive boiling events.  However, the underlying processes that control these events are still poorly understood.      The proposed experiment uses a transparent glass nozzle, in conjunction with an existing spray apparatus, to create a simple flow system with a controlled expansion.  The liquid will be heated upstream from the nozzle.  As the fluid expands through the nozzle it can become thermodynamically unstable, rapid boiling occurs, and a standing evaporation wave front can form.  Photographs are taken of the wave front.  In the second phase of the project ports will be fused onto the nozzle to accommodate pressure transducers and thermocouples.  These instruments will be used to acquire thermodynamic information about the wave.  The data from this system can be used to compare to the predictions from existing models.  The boiling process, which is thought to be quite different from common nucleate boiling behaviour, can also be carefully observed.      This work will have impact in three areas.  First, it will significantly advance our understanding of evaporation wave behaviour.  Second, it will suggest techniques for the control of flashing for useful purposes such as fuel injection, manufacturing, or coating processes.  And third, it will lead to strategies for controlling or mitigating accidental vapour explosions.  Overall, the results from this study will constitute a substantial data set that can be used to benchmark models of rapid evaporation.  The observations of the wave front will clarify the propagation mechanism, and the thermodynamic data will help to explain the energy output of these explosive events.  The combined information will make a significant contribution to the field.

拟议的研究是一项实验计划，旨在评估快速蒸发作为改善燃油喷雾雾化的一种手段。目前有许多相互竞争的模型来解释闪蒸喷雾、BLEVE（沸腾液体蒸发蒸气爆炸）、蒸汽爆炸和其他爆炸性沸腾事件中的快速相变，然而，控制这些事件的基本过程仍然知之甚少。 该实验使用一个透明的玻璃喷嘴，结合现有的喷雾装置，以创建一个简单的流动系统，控制膨胀。液体将在喷嘴上游加热。当流体通过喷嘴膨胀时，它会变得不稳定，发生快速沸腾，在第二阶段的项目中，端口将被熔接到喷嘴上，以容纳压力传感器和热电偶。这些仪器将被用来获取有关该波的热力学信息。来自该系统的数据可以用来与现有模型的预测进行比较。沸腾过程也可以被仔细观察到，这被认为与普通的核沸腾行为有很大不同。 这项工作将在三个方面产生影响。首先，它将极大地促进我们对蒸发波行为的理解。其次，它将提出用于燃料喷射、制造或涂层过程等有用目的的闪蒸控制技术。第三，它将导致控制或减轻意外蒸汽爆炸的战略。总的来说，这项研究的结果将构成一个可用于快速蒸发基准模型的大量数据集。2波前的观测将阐明传播机制，热力学数据将有助于解释这些爆炸事件的能量输出，这些信息的结合将对该领域做出重要贡献。