Abstract
A closed-loop control law employing compressor guided vanes is firstly investigated to solve unacceptable fuel flow dynamic change in single fuel control for turbo-shaft engine here, especially for rotorcraft in variable rotor speed process. Based on an Augmented Linear Quadratic Regulator (ALQR) algorithm, a dual-input, single-output robust control scheme is proposed for a turbo-shaft engine, involving not only the closed loop adjustment of fuel flow but also that of compressor guided vanes. Furthermore, compared to single fuel control, some digital simulation cases using this new scheme about variable rotor speed have been implemented on the basis of an integrated system of helicopter and engine model. The results depict that the command tracking performance to the free turbine rotor speed can be asymptotically realized. Moreover, the fuel flow transient process has been significantly improved, and the fuel consumption has been dramatically cut down by more than 2% while keeping the helicopter level fight unchanged.
Funding statement: Funding: Financial support from the Aerospace Science Foundation of China (No. 20120652) is gratefully acknowledged.
Nomenclature
- Wf
fuel flow (kg/s)
- χ
compressor guided vane angle (°)
- Ng, Np,NGB
relative rotor speed of gas and power turbine, multi-gearbox output shaft speed (%)
- SMC
stall margin of compressor (%)
- ΩR
main rotor speed (rad/s)
- Vx, Vy, Vz
velocities along X, Y and Z axis
- Ψ, Φ, Θ
yaw, roll and pitch angle of helicopter (°)
- θ0, A1c, B1s, θT
rotor collective, lateral cyclic pitch, longitudinal cyclic pitch (°)
- p, q, r
angular rate about X-axis, Y-axis and Z-axis with respect to airframe axes (rad/s)
- XS, YS, ZS
summed forces for all components of helicopter in direction of X, Y and Z axis with respect to airframe axes (N)
- LS, MS, NS
summed moments for all components of helicopter in direction of X, Y and Z axis with respect to airframe axes (N.m)
- IX, IY, IZ
moment of inertia about X, Y and Z axis with respect to airframe axes (kg.m2)
- IYZ
moment of inertia product about the crossing axis with respect to airframe axes (kg.m2)
lift coefficient of the blade section
drag coefficient of the blade section
number of blades
- B
chord length of the blade section, (m)
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