Numerical Investigation on Flow Characteristics and Aerodynamic Performance of a 1.5-Stage SCO2 Axial-Inflow Turbine with Labyrinth Seals

Abstract

The leakage problem of supercritical carbon dioxide (SCO2) axial-inflow turbine brings great challenges to the efficiency and security of the power system. Labyrinth seals are usually utilized to improve the leakage characteristics of the blade tip. In this paper, a 1.5-stage SCO2 axial-inflow turbine is established and labyrinth seals are arranged on the top of the first stage stator and rotor blades. The effects of seal clearance, groove on seal cavity surface and circle groove shape on flow characteristics and aerodynamic performance under different pressure ratio are investigated. Increasing seal clearance can significantly weaken the turbine performance. Arranging rectangle, circle and V-shaped grooves on the seal cavity surface near the outlet of the seal gap can enhance the energy dissipation, reduce the relative leakage and improve the power and efficiency. Increasing the groove width can improve the aerodynamic performance while the effect of the groove depth is weak. The configuration where the circle groove width is 50% of the pitch of seal tooth achieves the best performance with the relative leakage of stator1 and rotor, power and efficiency of 6.04 × 10−3, 8.09 × 10−3, 3.467 MW and 86.86% respectively. With an increase in pressure ratio, the relative leakage increases firstly and then remains almost constant. The power increases while the efficiency increases firstly and then decreases, reaching the peak value under the design condition.

Transient CFD Simulation on Dynamic Characteristics of Annular Seal under Large Eccentricities and Disturbances

“…represents the motion vector of moving rotor in Cartesian coordinates. di 1 denotes the vector from pi 0 to pi 1 (x 1 i , y 1 i ). Then, the new coordinates (x 1 f , y 1 f ) of pf 0 (current node pf 1 ) are defined as Equation 3.…”

“…The node of stator surface is assumed to stay still, the movement distance between rotor and stator is determined by the interpolation algorithm. Then, the new position coordinates (x 1 f , y 1 f ) of pi 1 could be expressed as Equation (4).…”

“…Hydraulic machinery such as pumps and turbines is widely applied in various energy fields, playing a significant role in energy development, utilization and transformation. The vibration caused by the fluid forces generated in gap seals of hydraulic machinery tend to have important effects on the efficiency and vibration of rotor system [1]. Due to the rise of safety and efficiency concerns, dynamic characteristics of various annular seals have been studied by researchers [2][3][4][5].…”

Vortex Patterns Investigation and Enstrophy Analysis in a Small Scale S-CO2 Axial Turbine

“…Ying et al [35] have made investigations on the influence of impeller shroud structure through analyzing 4-stage S-CO 2 axial turbines, the influence of impeller blade tip leakage flow and shroud leakage flow has been discussed. Du et al have studied the leakage characteristics and the effects of different seal methods in a 1.5-stage S-CO 2 axial-inflow turbine [36,37].…”

Orbit Decomposition Method for Rotordynamic Coefficients Identification of Annular Seals

“…Annular seals are widely used in turbomachinery to control the leakage flow through rotor-stator clearances from high-pressure regions to low-pressure regions [1,2]. Besides leakage flow reduction, annular seals are intended to serve as vibration damping devices.…”