Investigation on the Shock Control Using Grooved Surface in a Linear Turbine Nozzle

Abstract

Radial flow variable nozzle turbine (VNT) enables better matching between a turbocharger and engine and can improve the engine performance as well as decrease the engine emissions, especially when the engine works at low-end operation points. With increased nozzle loading, stronger shock wave and clearance leakage flow may be generated and consequently introduces strong rotor–stator interaction between turbine nozzle and rotor, which is a key concern of rotor high-cycle fatigue (HCF) failure. With the purpose of developing a low shock wave intensity turbine nozzle, the influence of grooved vane on the shock wave characteristics is investigated in the present paper. A Schlieren visualization experiment was first carried out on a linear turbine nozzle with smooth surface and the behavior of the shock wave was studied. Numerical simulations were also performed on the turbine nozzle. Guided by the visualization and numerical simulation, grooves were designed on the nozzle surface where the shock wave was originated and numerical simulations were performed to investigate the influence of grooves on the shock wave characteristics. Results indicate that for a smooth nozzle configuration, the intensity of the shock wave increases as the expansion ratios increase, while the onset position is shifted downstream to the nozzle trailing edge. For a nozzle configuration with grooved vane, the position of the shock wave onset is shifted upstream compared to the one with a smooth surface configuration, and the intensity of the shock wave and the static pressure (Ps) distortion at the nozzle vane exit plane are significantly depressed.

Effects of grooved vanes on shock wave and forced response in a turbocharger turbine

“…To validate this finding, a validation experiment was conducted on a linear turbine with a Schlieren photography system. More detailed information about the measurements and the experimental setup can be found in Lei et al 14 The experimental results expressed herein are only to provide partial validation to the steady CFD simulation.…”

“…With the aim of improving the reliability of a radial inflow turbine with nozzle vanes, a method of using a grooved surface on the nozzle vanes was proposed by Sun et al, 11 and, subsequently, more detailed analyses were reported in previous studies. 12–15 Following the previous research work, this article investigated the forced response of a turbine wheel by the coupled method of the computational fluid dynamics (CFD) simulations and the finite element analysis (FEA) calculations.…”

Variable nozzle turbocharger turbine performance improvement and shock wave alternation by distributing nozzle endwall clearances

“…More detailed information about the test rig and validations of numerical simulations can be found in prior publications. 20,21…”

“…More detailed information about the test rig and validations of numerical simulations can be found in prior publications. 20,21 Figure 13 also shows the flow characteristics of a shock wave and the leakage flow from the linear nozzle turbine vanes captured by the Schlieren photography system. It is fairly clear that the shock wave originates near the nozzle vane trailing edge and the nozzle endwall clearance leakage flow gradually drifts away from the nozzle vane during flowing downstream.…”

A General Framework for Designing 3D Impellers Using Topology Optimization and Additive Manufacturing

“…To meet the rising demand for energy, designing highly efficient turbomachinery systems [1] is an imperative activity. As a result, Oil & Gas companies are now facing major technological changes to improve their mechanical component quality and overall profitability.…”