Analysis of heat transfer on turbulence-generating ribs using dynamic mode decomposition

• Published in: International journal of heat and mass transfer 2020-02, Vol.147, p.118961, Article 118961
• Main Authors: Elmore, Michael, Fernandez, Erik, Kapat, Jayanta
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Contouring; Data analysis; Decomposition; DMD; Ducts; Fluid flow; Gas turbine engines; Gas turbines; Heat transfer; LES; Reynolds number; Ribbed duct cooling; Serpentine; Steady state models; Turbine blades; Turbulence
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2019.118961

•Introduces general method for finding a DMD mode which affects heat transfer.•LES used to extract DMD modes on a gas turbine cooling channel geometry.•CFD volume mesh morphed to excite or preturb these modes.•RANS CFD simulation not able to capture any engineering benefit from the morphed meshes. Ducts with turbulence-promoting ribs are common in heat transfer applications and can often found in the form of serpentine channels in gas turbine blades. This study uses a recent modal extraction technique called Dynamic Mode Decomposition (DMD) to determine mode shapes of the spatially and temporally complex flowfield inside a square ribbed (45 degree) duct at Reynolds number 32,400. One subject missing from current literature is a method of directly linking a mode to a certain engineering quantity of interest. Presented is a generalized methodology for producing such a link utilizing the data from the DMD analysis. Exciting the modes which are identified may cause the flow to change in such a way to promote the quantity of interest, in this case, heat transfer. This theory is tested by contouring the walls of the duct using the extracted mode shapes. An initial, unmodified geometry provides a baseline for comparison to later contoured models. The initial case is run as a steady-state RANS model. LES generates the necessary data for the DMD analysis. Several mode shapes extracted from the flow are applied to the duct walls and run again in the RANS model, then compared to the baseline, and their relative performance examined.