Compressor Performance Prediction via Conjugate Heat Transfer
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Solution Overview
Problem
Current compressor performance prediction methods using Computational Fluid Dynamics (CFD) fail to accurately model heat transfer through solid surfaces, leading to unrealistic efficiency predictions due to adiabatic modeling of boundaries, and do not account for heat transfer between the casing and environment, as well as differences in circumferential extent between rotor and stator stages.
Innovation Solution
A computer-implemented method that models compressor components as non-adiabatic solids, including rotor and stator interfaces with heat exchange links, and incorporates a stationary fluid domain to simulate natural heat transfer between the compressor and surroundings, accounting for differences in circumferential extent and using a Conjugate Heat Transfer (CHT) approach with iterative boundary condition adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solid boundaries are modelled as adiabatic in CFD calculations, then the computational domain can be simplified and calculations can be performed faster, but the predicted efficiency is lower and less realistic than actual compressor performance
Solution Approach 1:
The computational domain is segmented into distinct fluid regions and solid regions, with each region modeled using appropriate physics. The fluid domain uses Navier-Stokes equations while solid domains use heat conduction equations, allowing accurate heat transfer modeling without requiring the entire domain to use the more computationally intensive fluid solver.
Solution Approach 2:
An iterative coupling procedure acts as an intermediary between the fluid solver and solid solver, exchanging heat flux and temperature information at the fluid-solid interfaces. This mediator enables the two different physical models to work together efficiently, achieving accurate heat transfer prediction without the computational cost of a fully coupled fluid-structure solver.
2Measurement precision
If the computational domain is extended to include solid regions for Conjugate Heat Transfer modeling, then heat transfer through solid surfaces can be accurately captured, but the computational complexity and resource requirements increase significantly
Solution Approach 1:
The computational domain is segmented into distinct fluid regions and solid regions, with each region modeled using appropriate physics. The fluid domain uses Navier-Stokes equations while solid domains use heat conduction equations, allowing accurate heat transfer modeling without requiring the entire domain to use the more computationally intensive fluid solver.
Solution Approach 2:
The mathematical parameters governing heat transfer are changed based on the region type: fluid regions use full Navier-Stokes equations with viscous heating terms, while solid regions use simplified heat conduction equations. This parameter change reduces computational complexity in solid regions where full fluid dynamics are not needed.
3Measurement precision
If iterative adjustment of boundary conditions is used to obtain continuity of temperature and heat flux at fluid-solid boundaries, then accurate heat transfer prediction can be achieved, but the number of iterations required increases computational time
Solution Approach 1:
An iterative feedback loop continuously adjusts the boundary conditions at fluid-solid interfaces by comparing temperature and heat flux values from both sides. The solution from one iteration becomes the input for the next, with the process continuing until convergence criteria are met, ensuring accurate heat transfer prediction through systematic refinement.
4Ease of manufacture
If non-coinciding grids at the common boundary between fluid and solid domains are used, then flexibility in mesh generation is improved, but interpolation is required to pass boundary conditions which introduces additional numerical error
Solution Approach 1:
An iterative coupling procedure acts as an intermediary between the fluid solver and solid solver, exchanging heat flux and temperature information at the fluid-solid interfaces. This mediator enables the two different physical models to work together efficiently, achieving accurate heat transfer prediction without the computational cost of a fully coupled fluid-structure solver.
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 method provides a more realistic and accurate prediction of compressor performance by accounting for heat transfer between the casing and environment, and differences in circumferential extent, resulting in higher predicted efficiency and improved stage matching, with convergence typically achieved within 500-600 iterations.
Implementation Method 1
A possible state-of-the-art methodology, by means of which the computational domain is extended to the solid region, is known as Conjugate Heat Transfer (CHT) method
Implementation Method 2
a non-adiabatic Navier-Stokes (NS) solver for the flow in the fluid domain and a Finite Element_analysis (FEA) for the heat conduction in the solid parts of the turbines
Implementation Method 3
a stationary fluid domain on the top of the casing to account for heat transfer between the casing and the surrounding environment
Data Source
AI summary
Computer implemented method for prediction of performances of a compressor includes modelling a CFD gas path, modelling vanes and blades as non-adiabatic solids, building a model of the rotor including at least a first rotor solid domain facing a plurality of vanes non-adiabatic solids and at least a second plurality of rotor solid domains attached to a plurality of blades non-adiabatic solids, building a model of the stator including at least a first casing solid domain attached to a plurality of vanes non-adiabatic solids and at least a second casing solid domain facing a plurality of blades non-adiabatic solids, modelling one or more solid rotor interfaces, each solid rotor interface providing an heat exchange link between a respective pair of adjacent rotor solid domains, and modelling one or more solid stator interfaces, each solid rotor interface providing an heat exchange link between a respective pair of adjacent stator solid domains.