In this study, the effect of fuel temperature on cavitation inception, cavitation development structure, flow regime and near-field spray was explored, especially focus was put on a special kind of vortex-induced string-type cavitation and its effects on spray behavior. It can be seen that the higher the fuel temperature, the smaller the injection pressure corresponding to the cavitation inception is, and the faster it develops under the same injection pressure. The growth of geometry-induced near-wall cavitation at different fuel temperatures is weaker than that of vortex-induced string cavitation. The single initial bubble can be an origin for inducing the string cavitation after entering the nozzle orifice, whose intensity is larger at the higher fuel temperature. Although the effect of initial bubbles at the lower fuel temperature is weaker, continuous initial bubbles can still induce the formation of string cavitation and then stabilize it in the nozzle orifice. String cavitation initiated at the outlet is undemanding to occur at a higher temperature, and it becomes challenging to develop towards the inlet when the injection pressure increases. The frequency of the cloud cavitation shedding increases with the higher fuel temperature incurring a reduction in fuel viscosity. The variation of cavitation patterns at different fuel temperatures in diesel nozzles: The string cavitation intensity increases gradually as the injection pressure increases. Meanwhile, the growth of string cavitation area becomes faster with growing the temperature. When the injection pressure is increased to 0.6 MPa, further augment of the cavitation area is significantly limited due to the space limitation of the orifice, resulting in a slowdown of the growth rate. The development characteristics of string cavitation with temperature (h = 1 mm)

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不同燃油温度下柴油机喷油嘴空化形成不同形态的光学实验研究

本研究探讨了燃料温度对空化开始、空化发展结构、流态和近场喷雾的影响，特别关注了一种特殊的涡激弦型空化及其对喷雾行为的影响。可以看出，燃油温度越高，空化开始对应的喷射压力越小，在相同喷射压力下发展得越快。在不同燃料温度下几何诱导的近壁空化的增长弱于涡流诱导的串空化。单个初始气泡进入喷嘴孔口后可成为引起串空化的起源，其强度在燃料温度越高时越大。虽然在较低燃料温度下初始气泡的影响较弱，连续的初始气泡仍然可以诱导形成串空化，然后将其稳定在喷嘴孔口中。在出口处引发的管柱空化不需要在较高温度下发生，并且当注入压力增加时向入口发展变得具有挑战性。云气穴脱落的频率随着燃料温度的升高而增加，从而导致燃料粘度的降低。柴油机喷嘴在不同燃油温度下空化模式的变化：随着喷射压力的增加，串空化强度逐渐增加。同时，随着温度的升高，弦空化面积的增长变得更快。当注射压力增加到 0.6 MPa 时，由于孔口的空间限制，空化面积的进一步扩大受到显着限制，导致增长速度放缓。管弦空化随温度(h = 1 mm)的发展特性