The mixing of single or multiple jets is relevant in several engineering applications ranging from flame stabilisation in combustion to high lift devices for V/STOL aircraft. In some of these applications, expeditious manufacturing and ease of installation may dictate the use of sharp-edged slots in preference to nozzles with contoured upstream shaping.
It has been suggested that cruciform nozzle exit shapes may be suitable for improving mixing and thus thrust augmentation in STOL aircraft. The effects of nozzle geometry on the performance of an axisymmetric thrust augmentor have been investigated experimentally and a very slight improvement in the performance of the axisymmetric thrust augmentor was observed when cruciform nozzles were used after the tests had been performed with circular nozzles.