Unsteady 360 Computational Fluid Dynamics Validation of a Turbine Stage Mainstream/Disc Cavity Interaction Using Lattice-Boltzmann Method

Abstract

This paper is a continuation of a previous comparison dealing with URANS-based validation of the ASU-Honeywell turbine stage mainstream/disc-cavity interaction rig data. Here, the validation is with a CFD code named PowerFLOW which is based on the Lattice Boltzmann Method (or LBM). Transient LBM simulations were conducted across the previously published purge flows (Cw of 1540 to 6161), and at the higher mainstream flow condition of 2300 cfm (1.086m3/s). Sensitivity of convergence on results was investigated by increasing the number of revolutions, as well as by varying the passive scalar and temperature difference assumptions between mainstream and purge flow. Results indicate that at lower purge flow, LBM was able to significantly improve validation of sealing effectiveness measurements. For the intermediate purge flows, however, there is a departure from what the data shows. Finally, at the higher purge flow cases, LBM prediction improves at the outer radial location as compared to URANS. Moreover, on pressure validation, it has closed the gap in matching the measured steady pressures inside the lower disc cavity except at the highest purge flow. In the critical upper rim cavity, the gap between the two methods closes as purge flow increases. The outcome from this comparative tool validation study is that at the low critical purge flow case where ingestion is most critical as well as at the upper rim cavity location, sealing effectiveness predictions were significantly improved. The paper also discusses the current limitations of LBM.

Numerical and Experimental Investigation of Rim Cavity Sealing Performance in a Turbine Stator Well

“…Many rim cavity test rigs have been built to investigate the ingestion phenomena in different rim seal configurations and flow conditions. Most of them are equipped with pressure, temperature and also gas concentration measurements to evaluate the sealing performance by different methods (Coren et al 2010, Mirzamoghadam et al 2017, Clark et al 2017and Scobie et al 2017).…”

“…Using computational fluid dynamics (CFD) for simulating flow behavior in rim cavity/main stream zones started with relatively simple models (Hills et al 1997) and was improved over the years. Mirzamoghadam et al implemented the interface of stator and rotor domains in both upstream and downstream of cavity to investigate the impact of mixing plane location for simulations with sector models (Mirzamoghadam et al, 2008). In other researches, the instability of hot gas ingestion behavior by full 360-degree models was studied (Wang et al 2014 andMirzamoghadam et al 2017).…”

“…Mirzamoghadam et al implemented the interface of stator and rotor domains in both upstream and downstream of cavity to investigate the impact of mixing plane location for simulations with sector models (Mirzamoghadam et al, 2008). In other researches, the instability of hot gas ingestion behavior by full 360-degree models was studied (Wang et al 2014 andMirzamoghadam et al 2017). A comparison between different simulation approaches and experimental measurements was performed by Jakoby et al (Jakoby et al 2004).…”