Axial Turbomachine Blade Profiling for Flutter Damping
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Solution Overview
Problem
The design of axial turbomachine blades with increased aspect ratio tends to flutter, leading to material fatigue and inefficiency, and conventional methods to prevent flutter are either ineffective or costly and time-consuming.
Innovation Solution
A method for profiling blades that involves preparing a geometric model, calculating a time-dependent disruptive pressure profile, determining damping, modifying the model, and iteratively improving the oscillation mode to achieve enhanced damping properties, reducing the need for extensive numerical simulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the aspect ratio of blades is increased and blades are made thinner to improve efficiency, then the efficiency of the axial turbomachine is improved, but the blades tend to flutter leading to material fatigue and reduced reliability
Solution Approach 1:
The patent changes geometric parameters of the blade profile (such as thickness distribution, camber line, and aspect ratio) to achieve a balance between efficiency and flutter resistance. By optimizing these parameters, the blade can maintain high efficiency while avoiding flutter instability.
Solution Approach 2:
The patent employs composite material structures for blade construction, combining materials with different properties to achieve both high efficiency (through optimized geometry) and flutter resistance (through material damping and structural stiffness).
2Measurement precision
If conventional numerical oscillation simulations are performed extensively to evaluate blade profiles, then the accuracy of flutter prediction is improved, but the design process becomes time-consuming and expensive
Solution Approach 1:
The patent performs preliminary evaluation of blade profiles using simplified criteria (reduced frequency and OD Strouhal criterion) before conducting extensive numerical oscillation simulations. This preliminary screening eliminates obviously unsuitable profiles early in the design process, reducing the number of full simulations needed.
Solution Approach 2:
The patent uses feedback from preliminary evaluations and initial simulation results to refine the selection of blade profiles for detailed simulation. This iterative feedback process focuses computational resources on promising candidates, improving accuracy while reducing overall design time.
Data Source
AI summary
A method for profiling blades of an axial turbomachine includes preparing a geometric model of a blade profile; determining an oscillation mode of the geometric model; calculating a time profile of a position-dependent disruptive pressure in a channel between two adjacent blade profiles over an oscillation period of the oscillation belonging to the oscillation mode, changing the geometric model and determining a different oscillation mode for the modified geometric model; and determining the damping of the oscillation using the disruptive pressure profile calculated previously and accepting the modified geometric model for the case that the damping of the oscillation turns out to be greater than calculated, otherwise repeating the last two steps with another modified geometric model.