During engine operation, fan casing abradable liners are worn by the blade tip, resulting in
the formation of trenches. This paper describes the influence of these trenches on the fan
blade tip aerodynamics. A detailed understanding of the fan tip flow features for cropped and
trenched clearances is first developed. A parametric model is then used to model trenches in
the casing above the blade tip and varying blade tip positions. It is shown that increasing
clearance via a trench reduces performance by less than increasing clearance through …

During engine operation, fan casing abradable liners are worn by the blade tip, resulting in
the formation of trenches. This paper describes the influence of these trenches on the fan
blade tip aerodynamics. A detailed understanding of the fan tip flow features for cropped and
trenched clearances is first developed. A parametric model is then used to model trenches in
the casing above the blade tip and varying blade tip positions. It is shown that increasing
clearance via a trench reduces performance by less than increasing clearance through …