Better Metal-Temperature Calculations Faster with Conjugate Heat Transfer (CHT) and CFD
Tuesday, September 13, 2016

For power generation machinery involving three-dimensional, asymmetric hot fluid flows (such as gas turbines, steam turbines, turbochargers, heat exchangers, boilers, furnaces, etc.), Finite Element Analysis (FEA) will be required to assess whether those machines will be as durable as desired or instead prone to problems from thermal stress and fatigue. But why not use CHT with CFD to provide your FEA engineers with the most accurate metal temperatures possible, as inputs to their thermal stress calculations? This is especially applicable when the fluid temperature in the machinery varies significantly over time.

When it comes to doing thermal calculations for metal components, each of the traditional approaches has its own challenges and limitations:

  • Approach No. 1: using only finite element analysis (FEA) without any flow code – doesn’t account for the dynamic nature of the time-varying heat transfer between the fluid and solid regions. 
  • Approach No. 2: using FEA with a lower-fidelity 1-D flow calculation tool – doesn’t account for the complex 3-D turbulent flow interactions and dependencies between fluid and metal temperatures; the assumptions built into a 1-D flow approach are no longer valid or applicable. 
  • Approach No. 3: using FEA with 3-D CFD and Heat Transfer Coefficients (HTCs) – depends heavily on performing many separate CFD and FEA solutions with back-and-forth data transfer between each iteration. This approach is approximate (thus lower accuracy) as well as slow, laborious, and error-prone which doesn’t facilitate automated multi-simulation design exploration. 

To calculate the most accurate metal temperatures possible, in the shortest time, a dynamically coupled orconjugate heat transfer (CHT) solution embedded in your CFD tool is required in order to calculate the fluid and metal temperatures concurrently.

As you will see in this webinar, the CHT method available in leading simulation software is especially effective for discovering better thermal designs faster, due to the combination of several technologies particular to STAR-CCM+®:

  • A robust coupled solver that simultaneously solves for temperatures in both the solid and fluid regions of a system, capturing the dynamic fluid-structure interactions in the form of heat transferred between those regions.
  • Prism layer cells that adequately capture the boundary layer effects and thermal gradients which are so critical to ensuring proper heat transfer between solid and fluid regions.
  • Polyhedral cells that enable robust meshing of complex geometries and smooth transition from near-wall prism layer cells.
  • Conformal meshing between solid and fluid regions that readily enables the highly accurate calculation of the heat transferred between those regions, without the need for interpolation.
  • A pipelined workflow that enables rapid design iteration and A-to-B comparisons.

Best practices for performing CHT calculations will also be provided as part of this presentation and a live demonstration will be presented.

Jim Ryan
Chad Custer
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