Turbulence Models Assessment on the Flow and Heat Transfer in a S-Bend Passage with Ribs
Increased turbine inlet temperature is a guarantee of high thermal efficiency of gas turbines. However, temperatures in the hot gas path far exceed allowable material temperatures of turbine blades. Therefore, the blades are usually cooled by using extracted compressor air to flow through internal serpentine cooling channels. In order to provide better prediction of the methods to simulate heat transfer and flow on the internal channel, this paper mainly takes numerical simulation to investigate six kinds of different turbulence models and two wall functions for S-bend duct with ribs. Six turbulence models are employed for the predictions of these strongly strained turbulent flows, namely k-epsilon model ( k -ε ), RNG k-epsilon model (RNG k -ε ), SST model, BSL model, kOmega model ( K -ε ) and SSG Reynolds Stress model. Two wall functions are employed for the channel wall, which contain scalable wall functions and automatic wall functions. Wall functions are the most popular way to account for wall effects. In CFX, Scalable Wall Functions are used for all turbulence models based on the εequation. Fork-ε based models (including the SST model), an Automatic near-wall treatment method is applied. And then in order to compare this numerical simulation with experimental results, this paper has taken transient liquid crystal technique to investigate the heat transfer on the internal channels. The studied Reynolds numbers is 17625, and main flow temperature is 33OK. Both channel-1 and Channel-3 are trapezoidal shape, and channel2 is a rectangular channel, the airflow get into the entrance of the channel-1, and it outflow through the outlet-1, outlet-2 and Trailing edges outlet-3, and outflow ratio is 1:2:1. The ribs have staggered arrangement in the pressure-surface and the suctionsurface, channel-1 and channel-2 are rectangular ribs, channel-3 is triangle ribs. Detailed comparison is made among the results from the models and available experimental data to test the ability of the models in predicting these fluid flow and wall heat transfer problems. The results show that: it is critical to properly use turbulence models for numerical simulation. Under the same boundary conditions, the different turbulence models can carry out the different calculation s results, and the wall functions have an important effect on numerical simulations.
S-bend passage turbulence models heat transfer wall function
ZHENG Jie ZHU Hui-ren GUO Tao ZHAO Shu LIANG Wei-ying
School of Power and Energy, Northwestern Polytechnical University, Xian, China
国际会议
4th International Symposium on Jet Propulsion and Power Engineering(第四届喷气推进与动力工程国际会议 ISJPPE2012)
西安
英文
293-300
2012-09-10（万方平台首次上网日期，不代表论文的发表时间）