The present paper presents a numerical study of the impact of tip gap uncertainties in a multistage
turbine. It is well known that the rotor gap can change the gas turbine efficiency
but the impact of the
random variation of the clearance height has not been investigated before.
In this paper the
radial seals
clearance
of a
datum shroud geometry, representative of stea
m turbine
industrial practice, was
systematically varied and numeri
cally tested.
By using a Non
-
Intrusive
Uncertainty Quantification simulation based on a
Non
-
Intrusive Polynomial Chaos
, it is possible to
predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the
turbine blades.
This work shows that the impact of gap uncertainties propagates radially from the tip towards the hub of
the turbine and the complete span is affected by a variation of the rotor tip gap. This amplification of the
uncertainty is mainly due to the low aspe
ct ratio of the turbine and a similar behavior is expected in high
pressure turbines.