Glossary

What are transonic airfoils, and what is the active clearance control? Check out our technical dictionary and find out more about engine technology terms – from active clearance control to velocity triangle.

Geared fan Glass bead peening Grinding

Geared fan

Normally, the fan, the low-pressure compressor and the low-pressure turbine are fitted on one shaft. In contrast, a geared fan is "uncoupled" from the low-pressure system by means of a reduction gearbox. Thus, the low-pressure turbine and the low-pressure compressor can be operated at their respective optimum high speeds whereas the fan rotates at a much lower speed (ratio approx. 3:1). Advantages of the geared fan concept include a markedly improved overall engine efficiency and signification noise reduction.