One center body is channeled; the other has a conventional, smooth shape. The slots cut along the length of the channeled center body simulate a simple device that in an actual inlet would allow optimization of the amount of air flowing into the engine, resulting in improved airflow efficiency at a wide variety of speeds. This would improve fuel efficiency as well.

Six flights were flown, three with each center body installed. Flight tests were made incrementally at speeds up to Mach 1.74, or about 1.7 times the speed of sound. Flight data from the smooth center body were used to benchmark performance data for the channeled center body. Data points that NASA Dryden engineers collected during the experiment included inlet mass airflow information, internal surface pressure distribution numbers, and airflow distortion, or turbulence, data at the exit end of the device.

For more info, visit : http://www.nasa.gov/centers/dryden/Features/ccie.html