A Combined Experimental and Numerical Study of the Turbine Blade Tip Film Cooling Effectiveness Under Rotation Condition

Abstract

Detailed numerical and experimental investigations of film cooling effectiveness were conducted on the blade tips of the first rotor row pertaining to a three-stage research turbine. Four different blade tip ejection configurations were utilized to determine the impact of the hole arrangements on the film cooling effectiveness. Plane tip with tip hole cooling, squealer tip with tip hole cooling, plane tip with pressure side (PS) edge compound angle hole cooling, and squealer tip with PS-edge compound angle hole cooling. To avoid rotor imbalance, every pair is installed radially. Film cooling effectiveness measurements were performed for three blowing ratios (M) of 0.75, 1.25, and 1.75. Film cooling data was also obtained for three rotational speeds; 3000 rpm (reference condition), 2550 rpm and 2000 rpm. Film cooling measurements were performed using pressure sensitive paint (PSP) technique. In a parallel effort, extensive numerical investigations of the above configurations were performed to give a better view of flow behavior using a commercially available code. The experimental investigations were performed in the three-stage multipurpose turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University.

Computational Simulation of Deposition in a Cooled High-Pressure Turbine Stage With Hot Streaks

“…[28]. The k-x SST model was chosen because of its ability to predict bulk flow-field and heat transfer quantities in the context of a turbine stage, as well as more nuanced effects due to complex secondary flows, as demonstrated by several past studies [29][30][31][32][33]. A density-based solver was utilized in the implicit formulation, with convective fluxes determined using Roe's flux-difference splitting scheme.…”

Experimental Investigation of Rotor Tip Film Cooling at an Axial Turbine with Swirling Inflow Using Pressure Sensitive Paint

“…They could show that film cooling effectiveness in the squealer cavity may increase by up to 25% for a positive incidence angle of 5 • , while a negative incidence angle could increase or decrease the film cooling effectiveness locally depending on the blowing ratio. Rezasoltani et al [5] conducted measurements at a rotating rig for different cooled and uncooled blade tips. They concluded that the flow behaviour is strongly affected by the film cooling injection and that the film effectiveness follows the net velocity vector caused by the incidence and over-tip leakage.…”

“…At the turbine inlet, a full-annular combustion simulator with exchangeable swirlers creates engine-representative flow angles at the combustor-turbine-interface. A realistic cooling configuration is simulated by ejecting secondary air at various positions (Figure 1), including film cooling at the end wall upstream of the NGV, the so-called Rear Inner Discharge Nozzles (RIDN) (1), purge flow between NGV and rotor (2), film cooling at the NGV leading edge (3), slot ejection at the NGV trailing edge (4), and film cooling at the rotor tip (5). The operating point of the rig is summarized in Figure 1.…”

“…ii. A specific Phase-Locked Method based on Intensity: Here, a synchronized strobe light is used as well [5,18]. However, the image sensor is read out every revolution, thus limiting the collected signal.…”

A Review of Hole Geometry and Coolant Density Effect on Film Cooling

“…However, significant improvements were observed in both simple angled and compound angled cylindrical holes at higher blowing ratios and density ratio (DR = 2). Rezasoltani et al (2015) conducted an experimental and numerical study to understand the effect of four different blade tip ejection configurations (hole arrangements) on the effectiveness. The holes were installed on the blade tips of the first rotor row of a 3-stage research turbine and hence the effect of rotation was also evaluated.…”