Transitional turbulator

An air-to-air charge air cooler for cooling air supplied to an internal combustion engine, comprising:

• a tube assembly including a plurality of tubes extending in a longitudinal direction,
• wherein the plurality of tubes are arranged adjacent to one another, and
• wherein each of the plurality of tubes includes an inlet to receive airflow and an outlet to output the airflow;
• and
• a first turbulator and a second turbulator arranged in at least a first one of the plurality of tubes, each of the first and second turbulators having a pitch defined in a direction transverse to airflow through the first one of the plurality of tubes,
• wherein the pitch varies in at least one of the longitudinal direction and the transverse direction of the first one of the plurality of tubes,
• wherein the first turbulator has a first pitch and the second turbulator has a second pitch that is less than the first pitch,
• wherein the first turbulator is arranged adjacent to the second turbulator in the transverse direction in the first one of the plurality of tubes, and
• wherein the amount by which the second turbulator extends in the transverse direction is in a range from 25% to 75% of the width of the first one of the plurality of tubes.