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US 9,791,311 B2Granted
Rotating blade analysis
AssigneeROLLS-ROYCE plc
InventorOlivier Jousselin
Life of this patent
Estimating the term…
Abstract
Methods are provided for: (i) measuring the position of the blade stagger angle axis for one or more blades of a row of blades attached to a rotor, (ii) measuring the blade tip stagger angle for one or more such blades, and (iii) measuring the blade tip axial displacement for one or more such blades. The methods use forward and rearward blade tip timing datasets for successive rotations of the blades from two axially spaced blade tip timing probes. The forward probe is forward of the rearward probe along the axial direction of the rotor. The blade tip timing datasets allow the times of arrival of the blades at the respective probes to be measured. The methods also use a once per revolution dataset for the successive rotations of the blades. The once per revolution dataset allows the angular velocity of the blades to be measured.
Claims24
A method of measuring the position of the blade stagger angle axis for one or more blades of a row of blades attached to a rotor, the method comprising the steps of:
- during rotation of the rotor, obtaining forward and rearward blade tip timing datasets for successive rotations of the blades from two axially spaced blade tip timing probes, a forward one of the blade tip timing probes being forward of a rearward one of the probes along the axial direction of the rotor, the forward and reward blade tip timing datasets allowing times of arrival of the blades at the respective probes to be measured;
- during rotation of the rotor, obtaining a once per revolution dataset for said successive rotations of the blades, the once per revolution dataset allowing angular velocity of the blades to be measured;
- determining, from the forward and rearward blade tip timing datasets, measured blade tip times of arrival at the forward and rearward probes of a blade for a reference revolution of the blades;
- determining, from the once per revolution dataset, predicted blade tip times of arrival at the forward and rearward probes of the blade for a further revolution of the blades assuming that there is no change in shape or relative position of the blade;
- determining, from the forward and rearward blade tip timing datasets, measured blade tip times of arrival at the forward and rearward probes of the blade for said further revolution of the blades;
- calculating the position of the blade stagger angle axis of the blade at said further revolution from the expression:
- DFA=DFR(ΔF/(ΔF+ΔR))
- or from the expression:
- DRA=DFR(ΔR/(ΔF+ΔR))
- where DFA is the distance along the axial direction of the rotor between the forward probe and the position of the blade stagger angle axis, DRA is the distance along the axial direction of the rotor between the rearward probe and the position of the blade stagger angle axis, DFR is the distance along the axial direction of the rotor between the forward probe and the rearward probe, ΔF is the difference between the measured blade tip time of arrival of the blade at the forward probe and the predicted blade tip time of arrival of the blade at the forward probe for said further revolution, and ΔR is the difference between the measured blade tip time of arrival of the blade at the rearward probe and the predicted blade tip time of arrival of the blade at the rearward probe for said further revolution;
- and
- performing a blade tip timing calibration based upon the calculated position of the blade stagger angle axis of the blade.
9 more elements
A method of measuring the blade tip stagger angle for one or more blades of a row of blades attached to a rotor, the method comprising the steps of:
- during rotation of the rotor, obtaining forward and rearward blade tip timing datasets for successive rotations of the blades from two axially spaced blade tip timing probes, a forward one of the blade tip timing probes being forward of a rearward one of the probes along the axial direction of the rotor, the forward and reward blade tip timing datasets allowing times of arrival of the blades at the respective probes to be measured;
- during rotation of the rotor, obtaining a once per revolution dataset for said successive rotations of the blades, the once per revolution dataset allowing angular velocity of the blades to be measured;
- determining, from the forward and rearward blade tip timing datasets, measured blade tip times of arrival at the forward and rearward probes of a blade for a revolution of the blades;
- calculating the blade tip stagger angle of the blade at said revolution from the expressions:
- θ=a tan((R((αF−αR)−Δα))/DFR)
- and
- Δα=ω(TmF−TmR)
- where θ is the blade tip stagger angle of the blade at said revolution, DFR is the distance along the axial direction of the rotor between the forward probe and the rearward probe, R is the radial distance from the tip of the blades to the axis of the rotor, αF is the angular position of the forward probe, αR is the angular position of the rearward probe, ω is the measured angular velocity of the blades at said revolution, TmF is the measured blade tip time of arrival of the blade at the forward probe at said revolution, and TmR is the measured blade tip time of arrival of the blade at the rearward probe at said revolution;
- and
- performing a blade tip timing calibration based upon the calculated blade tip stagger angle of the blade.
7 more elements
A method of measuring the blade tip axial displacement for one or more blades of a row of blades attached to a rotor, the method comprising the steps of:
- during rotation of the rotor, obtaining forward and rearward blade tip timing datasets for successive rotations of the blades from two axially spaced blade tip timing probes, a forward one of the blade tip timing probes being forward of a rearward one of the probes along the axial direction of the rotor, the forward and reward blade tip timing datasets allowing times of arrival of the blades at the respective probes to be measured;
- during rotation of the rotor, obtaining a once per revolution dataset for said successive rotations of the blades, the once per revolution dataset allowing angular velocity of the blades to be measured;
- determining, from the forward and rearward blade tip timing datasets, measured blade tip times of arrival at the forward and rearward probes of a blade for a reference revolution of the blades;
- determining, from the once per revolution dataset, predicted blade tip times of arrival at the forward and rearward probes of the blade for a further revolution of the blades assuming that there is no change in shape or relative position of the blade;
- determining, from the forward and rearward blade tip timing datasets, measured blade tip times of arrival at the forward and rearward probes of the blade for said further revolution of the blades;
- calculating the position of the blade stagger angle axis of the blade at said further revolution from the expression:
- DFA=DFR(ΔF/(ΔF+ΔR))
- or from the expression:
- DRA=DFR(ΔR/(ΔF+ΔR))
- where DFA is the distance along the axial direction of the rotor between the forward probe and the position of the blade stagger angle axis, DRA is the distance along the axial direction of the rotor between the rearward probe and the position of the blade stagger angle axis, DFR is the distance along the axial direction of the rotor between the forward probe and the rearward probe, ΔF is the difference between the measured blade tip time of arrival of the blade at the forward probe and the predicted blade tip time of arrival of the blade at the forward probe for said further revolution, and ΔR is the difference between the measured blade tip time of arrival of the blade at the rearward probe and the predicted blade tip time of arrival of the blade at the rearward probe for said further revolution;
- calculating the blade tip stagger angle of the blade for each of a reference and further revolutions from the expressions:
- θ=a tan((R((αF−αR)−Δα))/DFR)
- and
- Δα=ω(TmF−TmR)
- where θ is the blade tip stagger angle of the blade at each revolution, DFR is the distance along the axial direction of the rotor between the forward probe and the rearward probe, R is the radial distance from the tip of the blades to the axis of the rotor, αF is the angular position of the forward probe, αR is the angular position of the rearward probe, ω is the measured angular velocity of the blades at each revolution, TmF is the measured blade tip time of arrival of the blade at the forward probe at each revolution, and TmR is the measured blade tip time of arrival of the blade at the rearward probe at each revolution;
- determining updated predicted blade tip times of arrival at the forward and rearward probes of the blade for said further revolution from the expressions:
- TPF,fur=TmF,refωref/ωfur−DFA,fur(tan(θfur)−tan(θref))/(Rωfur)
- and
- TPR,fur=TmR,refωref/ωfur+DRA,fur(tan(θfur)−tan(θref))/(Rωfur)
- where TpF, fur and TpR,fur are updated predicted blade tip times of arrival of the blade at respectively the forward and rearward probes at said further revolution and relative to the start of said further revolution, TmF,ref and TmR,ref are the measured blade tip times of arrival of the blade at respectively the forward and rearward probes at said reference revolution and relative to the start of said reference revolution, ωref and ωfur are the measured angular velocities of the blades at respectively said reference revolution and said further revolution, DFA,fur and DRA,fur are the distances along the axial direction of the rotor between respectively the forward probe and the position of the blade stagger angle axis of the blade and the rearward probe and the position of the blade stagger angle axis of the blade at said further revolution, and θref and θfur are the blade tip stagger angles of the blade at respectively said reference revolution and said further revolution;
- and
- determining the blade tip axial displacement at said further revolution relative to the blade tip axial position at said reference revolution from the expressions:
- Δax=(2πRΔtcts)/(ωfur tan(θfur))
- and
- Δtcts=(TmF,fur−TpF,fur)−(TmR,fur−TpR,fur)
- where Δax is the blade tip axial displacement at said further revolution relative to the blade tip axial position at said reference revolution, and TmF,fur and TmR,fur are the measured times of arrival of the blade at respectively the forward and rearward probes at said further revolution and relative to the start of said further revolution;
- and
- performing a blade tip timing calibration based upon the calculated blade tip axial displacement of the blade.
25 more elements
Dependencies are inferred from the claim text.