Non-uniform Nozzle Vane Spacing for Turbomachine Noise Reduction
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Solution Overview
Problem
Turbomachines, such as turbines, experience noise due to periodic changes in force on blades caused by wakes in the working fluid, leading to concentrated vibration energy at a single frequency, resulting in excessive noise.
Innovation Solution
A stator with non-uniformly spaced nozzle vanes arranged in a repeating pattern, creating different profiles for the nozzles to distribute vibration energy among multiple side band frequencies instead of focusing it at a single frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nozzle vanes are uniformly spaced, then the structure is simple and easy to manufacture, but vibration energy is concentrated at a single frequency, maximizing noise amplitude
Solution Approach 1:
The patent applies asymmetry by transitioning from uniform to non-uniform nozzle vane spacing. The nozzle vanes are positioned at varying circumferential intervals, creating an asymmetric distribution pattern that spreads vibration energy across multiple frequencies. This asymmetric arrangement disrupts the periodic wake interaction that causes concentrated vibration at a single frequency, thereby reducing peak noise amplitude while maintaining manufacturing feasibility through controlled variation in spacing.
Solution Approach 2:
The patent implements parameter changes by modifying the spacing parameter of nozzle vanes from a constant uniform value to a variable non-uniform distribution. The circumferential spacing between adjacent nozzle vanes is varied according to a specific pattern, changing the spatial parameter to achieve frequency distribution of vibration energy. This parameter variation allows the system to reduce noise amplitude by spreading energy across multiple frequencies rather than concentrating it at one frequency.
2Object-generated harmful factors
If nozzle vanes are non-uniformly spaced to reduce noise, then vibration energy is distributed over multiple frequencies, but imbalance or axial thrust may be caused
Solution Approach 1:
The patent applies local quality by implementing non-uniform nozzle vane spacing that varies in specific local regions while maintaining overall balance. Different sections of the stator have different spacing patterns, creating local variations in wake distribution that spread vibration energy frequency-wise. The local quality variations are designed to reduce peak noise amplitude in specific frequency ranges while the overall distribution is controlled to prevent excessive imbalance or axial thrust on the rotor.
Data Source
AI summary
A stator for a turbomachine. The stator includes a plurality of nozzle vanes, with the distance between each of the plurality of nozzle vanes varying circumferentially around the stator in a repeating pattern configured to distribute a vibration energy over a plurality of side band vibration frequencies around a nominal passing frequency in a rotor.