Frozen Gust Analysis via Time-Transformation Pitch-Change Model
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Solution Overview
Problem
Current computational fluid dynamics (CFD) methods for modeling fluid flow in turbomachines require full-domain modeling, which is computationally expensive and impractical due to high processing burdens and memory requirements, especially when dealing with pitch changes between blade rows.
Innovation Solution
The implementation of a time-transformation pitch-change model and harmonic analysis method, which allows for reduced geometry modeling by transforming governing flow equations in time and representing flow variables as a Fourier series, enabling faster and more efficient solutions using a steady-state method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-domain modeling is used to model fluid flow in turbomachines, then accuracy is improved, but computational cost and processing burden increase significantly
Solution Approach 1:
The patent divides the turbomachine into multiple blade rows and applies frozen gust analysis to individual blade rows rather than modeling the entire domain. This segmentation allows the second blade row to be analyzed independently with wake profiles imposed from the first blade row, significantly reducing computational resources while maintaining accuracy for pitch change analysis
Solution Approach 2:
The patent extracts and imposes wake profiles from the first blade row onto the second blade row, separating the modeling of blade rows. This extraction allows the second blade row to be solved without explicitly modeling the first blade row geometry, reducing computational burden while preserving the influence of upstream blade rows through the imposed wake conditions
2Measurement precision
If full-domain modeling is used to account for pitch changes between blade rows, then accuracy is improved, but memory requirements increase significantly
Solution Approach 1:
The patent segments the pitch change analysis to be performed locally at each blade row interface through wake profile imposition rather than requiring full-domain storage. This allows pitch differences between blade rows to be accurately captured while minimizing memory requirements by not storing complete three-dimensional geometry data for all blade rows simultaneously
Solution Approach 2:
The patent creates simplified representations of wake profiles from upstream blade rows and imposes them on downstream blade rows. These copied wake profiles capture the essential pitch change effects without requiring storage of the complete upstream blade row geometry, significantly reducing memory requirements while maintaining analysis accuracy
3Productivity
If reduced geometry modeling is used to decrease computational resources, then processing efficiency is improved, but accuracy may be compromised
Solution Approach 1:
The patent introduces wake profiles as intermediary representations that carry the essential flow information from upstream blade rows to downstream blade rows. These wake profiles serve as mediators that preserve accuracy by capturing the influence of pitch changes and upstream effects without requiring full-domain modeling, thus maintaining precision while achieving computational efficiency
Solution Approach 2:
The patent transforms the governing flow equations in time to resolve pitch differences between imposed wake profiles and modeled blade passages. This parameter transformation allows the reduced geometry model to accurately capture pitch change effects by modifying the temporal representation of the flow equations rather than requiring complete geometric fidelity
Data Source
AI summary
Systems and methods are provided for modeling fluid flow in a turbomachine. A specification of a system including first and second blade rows is received. A wake profile from the first blade row is imposed on the second blade row to approximate an influence of the first blade row on the second blade row. Governing flow equations for the fluid flow in the second blade row are transformed in time. Flow variables of the transformed governing flow equations are represented as a Fourier series, and the Fourier series representation is substituted into the transformed governing flow equations to obtain a modified form of the transformed governing flow equations. A pseudo-time term is introduced into the modified form of the transformed governing flow equations. The modified form of the transformed governing flow equations is solved using the steady-state solution method to model the fluid flow in the second blade row.