Jet Injections for Optimum Mixing in Pipe Flow

The use of jet injections, as contrasted to injections with no momentum, can help to reduce the pipe flow distance required for the mixing of injected and ambient fluids without requiring appurtenances or devices inside the pipe. For uniform, turbulent flow, experiments were conducted to determine the optimum injection conditions for a single jet at the pipe wall at 90° to 150° relative to the ambient flow, and for two jets at 90°. Depending on the type of injection and the desired degree of mixing, the required flow distance can be reduced up to 70 percent compared to injection with no momentum. For uniform flow, there are only small benefits from using more than two injection points. However, the two experiments which were conducted with a secondary current in the pipe flow indicated greater benefits from using multiple-point injection.