Controlling secondary flow development is key to high efficiency turbine stages that must employ low aspect ratio blades.
The design of a turbomachine is a trade-off between many disciplines. There are instances where the overall efficiency of a machine is optimised even though the aerodynamics of a particular component are challenged. Such a situation often arises in the first stage of the low pressure turbine (or the intermediate pressure turbine of a three shaft engine) of an aero-engine. A typical requirement for the stator row of these turbines is that they must be thick enough to allow a structural support or an oil service pipe to pass through the main flow path into the centre of the engine. This leads to thick profiles with a low aspect ratio (span-to-chord ratio). The aerodynamics of low aspect ratio blades, particularly high turning ones, are dominated by secondary flows and are expected to suffer an associated performance penalty.Associated Team