衝擊式噴霧由兩股或多股噴流相互衝擊碰撞產生霧化，被廣泛應用於小型雙推進劑液態火箭。在實際火箭的操作狀況中，衝擊碰撞的過程不僅會使得燃料和氧化劑產生霧化並且完成混合的行為。
本研究以酒精和純水作為兩異質溶液，探討異質衝擊霧化與混合特性，並且與同質純水衝擊霧化的結果作比較。研究的內容包括衝擊液膜型態、衝擊霧化特性的流場觀測、霧化液滴的平均粒徑分佈，和異質流場混合分佈。
在衝擊液膜的型態方面，和同質衝擊液膜現象不同的是，異質衝擊液膜在60˚衝擊角會存在著一過渡模式，90˚衝擊角在封閉液緣模式和開放液緣模式下會有波狀破裂模式出現。另一方面，異質液膜的液膜生成的穩定性較同質的液膜差，在封閉液緣下的長寬比呈現先降後昇趨勢，不同於同質液膜幾乎成定值的現象。
對於衝擊霧化的特性而言，液膜偏移角度與理論推導的結果相當符合。同質衝擊霧化不管在與液膜平行或垂直的方向上都呈現對稱的形狀，然而，異質衝擊霧化僅在與液膜垂直的方向上呈現對稱的形狀，在液膜平行的方向上，則出現霧化中心些微的偏移，使得液膜產生彎曲的現象。另一方面，在不同孔徑的衝擊組合中可以明顯觀察到，由於噴流碰撞接觸的部分動量分佈不平衡，所造成的液膜彎曲現象。
經由粒徑量測的結果分析，同質和異質衝擊霧化液滴的平均粒徑皆隨著噴流速度與衝擊角度變大而減小，其減小的趨勢會隨噴流速度加大而逐漸的變緩，並且在側向位置(與液膜平行方向)上顯示對稱的粒徑分佈。然而，在正向位置(與液膜垂直方向)上，異質霧化的液滴粒徑分佈為非對稱性，原因與液膜的彎曲變形和液滴的局部混合的物理性質不同有關。一般而言，異質衝擊霧化液滴受到其工作流體的物理性質影響，使得其粒徑的大小分佈小於同質衝擊霧化液滴。
在異質流場混合分佈方面，霧化的中心剖面在側向位置上密度幾乎不變。在正向位置上，密度的趨勢皆呈遞減的狀態，較大密度的分佈在較小密度噴流下方處，顯示兩股噴流在碰撞後，經過霧化混合狀態後，仍沿著原先的動量方向前進。此現象為穿透式霧化模式，當噴流速度與衝擊角度越大，會使得穿透式霧化越為明顯。

Atomization of impinging jets is generated by the impingement of two or more liquid streams of the bipropellant liquid rocket. Fuel and oxidizer are impinged on each other in practical rocket engines, the outcome of which is spray of the liquid into small drops and mixing of both of them.
The objectives of this study are to investigate the flow patterns, atomization characteristics, mean droplet size (SMD), and mixture ratio distribution of the unlike-doublet impinging jets. Most of the experimental results are compared with those of like-doublet impinging jets.
For the flow patterns of unlike-doublet impinging jets, there exists a transition mode under 60˚ impingement. For 90˚ impingement, wave mode appears in close rim and open rim mode. On the other hand, it is noted that the flow pattern of unlike-impinging jets is more unstable than the like one because of the difference of liquid property.
For the other atomization characteristic, the deviation angle of sheet related to the resultant momentum is consistent with theoretical prediction. The spray distribution of like-doublet impingement is symmetric in both lateral and normal direction of sheet. However, the unlike-doublet one is symmetric only in normal direction. In lateral direction, the center of the spray reveals a little shift, which makes a bend of the spray. The phenomenon of bend sheet becomes more obvious for impinging jets with different orifice diameter.
The SMD of like- and unlike-impingement decreases with the increase of jet velocity and impinging angle. For unlike-impingement, it reveals asymmetric distribution in normal position. This should be caused by the bend of the spray and local mixing droplet of different physical property. Results also show that the SMD is smaller for the unlike-doublet impingement then the like-doublet impingement.
As the mixture ratio distribution is concerned, the region of higher density appears below the jet of lower density, the density changes linearly in the direction of jets. It reveals that both unlike liquid streams penetrate through each other, and still maintain in the original direction of jet momentum after impingement. The phenomenon is based on transmitive atomization, the higher the jet velocity and the impinging angle, the higher the degree of stream crossing.

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