AbstractIn this thesis, the flow and heat transfer in dimpled channels have been investigated using the Reynolds-averaged Navier-Stokes (RANS) approach. The primary objective of this investigation is to identify the capabilities of RANS models to reproduce the characteristics of the flow and heat transfer in dimples. The flow in dimpled channels has been chosen as the test case due to their relevance to gas turbine cooling applications, as well as the fairly complex flow features over dimples, which poses a challenge to turbulence modelling. Five turbulence models have been tested in the present work. These include: the Launder and Sharma k-epsilon model, both the Craft et al. (1996) and (2000) cubic k-epsilon models, the Hanjalic and Jakirlic Reynolds stress model (RSM), as well as the Craft (1998) two-component limit (TCL) RSM. The models have been chosen such that all three classes of RANS closure were tested. The tested models have been applied to two dimpled channel configurations with increasing complexity. In the first, the flow over a single dimple in a channel has been considered, while in the second, the case of a staggered array of dimples has been examined. Moreover, across these two configurations, the effect of the dimple depth, the channel height and the Reynolds number have also been investigated. The results show that all models produce a physically viable solution for the problem of the flow in dimpled channels. Nevertheless, the Craft et al. (1996) and (2000) cubic k-Îµ models, as well as the Craft (1998) TCL RSM, predicted dimple flow structures that deviate from the expected state. In general, the main flow characteristics are reproduced by the RANS models, and the predicted mean velocity profiles are in good agreement with the data. All models report an overall enhancement in heat transfer levels when using dimples in comparison to those of a plane channel.
|Date of Award||1 Aug 2018|
|Supervisor||Timothy Craft (Supervisor) & Hector Iacovides (Supervisor)|
- Turbulence Modelling