Turbomachine Rotor with Aperiodic Blade Angles
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Solution Overview
Problem
Turbomachines face challenges in ensuring structural integrity during the speed rise phase due to vibratory excitations related to natural frequencies, requiring costly and time-consuming tests to avoid compromising the machine's integrity.
Innovation Solution
A rotor design featuring blades fixed to a disc via lattice structures that change angle of incidence with rotational speed, resulting in an aperiodic distribution of angles when stationary, reducing critical natural modes and potentially eliminating the need for tests by detuning the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the aerodynamic profile of blades is optimized at a nominal operating point, then the performance at that point is maximized, but vibratory excitations occur during speed rise phase through natural frequencies
Solution Approach 1:
The patent applies asymmetry by creating an aperiodic distribution of blade angles of incidence around the disc when stationary. This asymmetric configuration detunes the rotor structure, reducing the number of critical natural modes that could be excited during speed rise, thereby preventing resonant vibrations while maintaining optimal performance at the nominal operating point.
Solution Approach 2:
The patent implements dynamics by configuring the blades and lattice structures so that the angle of incidence changes automatically with rotational speed. During speed rise, the blades dynamically adjust their angles, which prevents the rotor from settling into resonant conditions at critical speeds, thus maintaining structural integrity without compromising nominal point performance.
2Ease of manufacture
If conventional rotor design with periodic blade distribution is used, then manufacturing is simplified, but costly and time-consuming tests are required to ensure structural integrity
Solution Approach 1:
The aperiodic distribution of blade angles maintains manufacturing feasibility through systematic configuration methods while fundamentally changing the dynamic characteristics of the rotor. This asymmetric design inherently reduces vibratory excitations during speed rise, allowing the manufacturer to eliminate or significantly reduce the number of costly structural integrity tests required for conventional periodic designs.
3Reliability
If the number of natural frequencies during speed rise is reduced, then vibratory excitations are minimized, but the design complexity of the rotor increases
Solution Approach 1:
The patent applies local quality by configuring each blade-lattice structure with specific angle characteristics that collectively create the aperiodic distribution. Rather than uniformly modifying all blades, the design assigns locally optimized properties to different blade positions, reducing critical natural modes while keeping the overall design methodology systematic and manageable.
Solution Approach 2:
The patent implements parameter changes by varying the angle of incidence parameter for each blade in a controlled aperiodic pattern. This systematic variation of geometric parameters detunes the rotor structure to minimize natural frequencies during speed rise, achieving reduced vibratory excitations through manageable parameter optimization rather than complex structural modifications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the number and amplitude of vibratory excitations during speed rise, lowering the cost and complexity of turbomachine testing and manufacturing, while ensuring structural integrity and optimal performance at nominal operating points.
Implementation Method 1
the change in the angle of incidence of the blades takes place by itself, thanks to the centrifugal force due to the rotational speed of the rotor, as this rotational speed increases
Data Source
AI summary
A rotor for a turbomachine includes a disc and a plurality of blades fixed to the disc. Each blade of the plurality of blades is fixed to the disc via a lattice structure configured so that a tensile force applied to the lattice structure induces a change in the angle of incidence of the blade. The blades and the lattice structures are configured so that: (i) when the rotor is stationary, the distribution of the angles of incidence of the blades around the disc is aperiodic, and (ii) when the rotor is rotating at a predetermined rotational speed, the angles of incidence of the blades are identical.