On the Physics of Vortex Formation at the Tip of a Turbine Blade

Abstract

The vortical flow at the blade tip area of a turbine rotor has a great effect on the aerothermal performance of the blade tip of turbine rotor however its physics is not fully understood. The present paper is a numerical study to investigate the physics behind vortex formation at the blade tip area. The blade under investigation is a linear model of the tip section of the GE-E3 high-pressure turbine first stage rotor blade. Calculations were carried out for three tip geometries, namely, conventional double squealer, thick pressure side squealer and thick suction side squealer. The code used in this study is an in-house, unstructured, finite volume, multiblock, 3D, compressible, viscous solver. The turbulent viscosity was calculated using the Delayed Detached Eddy Simulation (DDES) model. Computational results show that the vortex formation depends on the vorticity imparted with the incoming flow. Therefore, the flow with high velocity gradient caused larger vortex than that with low velocity gradient. This result is valid for both the cavity vortex as well as the leakage vortex.

Vortex Suppression on High Subsonic Turbine Blade via Micro Holes (30 Degree)

“…DES turbulence model cannot capture the primary three pressure minima observed in the experiment at the location of S/D ≈ −0.7, 0.0, and 0.75. This is believed due to grid size on DES model destruction part particularly smaller than boundary layer [22]. However, DDES turbulence model can capture three locations of minimal pressure, which is prove that the influence of length scale solution in turbomachinery is very important.…”

“…For simulation calculation on turbine blade related, the possibility of a boundary layer is less than minimum grid size, which frequently happens since d is grid size-dependent. To overcome this, DDES (Delayed Detached Eddy Simulation) has added parameter rd in the basic Spalart-Allmaras model [22]…”

“…where uijk is velocity profile and fd is 1 in the Large Eddy Simulation (LES) region, and rd << 1 and equal zero in the Reynolds Average Navier-Stokes (RANS) region [22]. ĸ is von Karman constant (0.41) and υT is kinematic eddy viscosity.…”

A study of angle parametric optimization of the composite honeycomb on turbine blade tip

“…A variety of tip leakage flow control methods have been proposed, and flow control is divided into active flow control and passive flow control based on a study by Lord et al 4 The two control methods are distinguished by the presence or absence of external energy. For example, tip winglets, 5,6 ribs, 7 squealers, 8,9 and casing contouring 10 are considered passive control methods. Tip injection 11,12 and plasma actuators 13 are classified as active control methods.…”