Flow Visualization by Direct Injection Technique

The use of flow visualization often plays a defining role in the understanding of many fluid flow problems. Through the use of direct injection flow visualization, the researcher may be afforded either a global view of a complex flow field or the enhanced understanding of a critical flow feature. The current article serves to introduce the reader to several commonly practiced direct injection flow visualization techniques including smoke injection, smoke wire, chemical reactions and helium bubbles. Several considerations for the use of each of these techniques are provided along with multiple examples of the use of direct injection flow visualization. Keywords: direct injection; smoke tube; smoke wire; chemical reactions; helium bubble