Numerical simulations are carried out to investigate the flow structure in blade tip region of axial compressors. Various clearance heights and end wall motion conditions a linear compressor cascade studied assess effect vorticity transport on leakage (TLF). Moreover, TLF rotor at different operating is using delayed detached eddy simulation. The results show that both plays an important role roll-up evolution vortex (TLV), resulting great impacts loss stability TLV. It found TLV composed...

The evolution of unsteady vortex structures in the tip region an axial compressor rotor is investigated based on delayed detached eddy simulation. are identified by LTcri method, and velocity fields visualized particle tracing method. results show that leakage (TLV) can be divided into three phases: generation phase, development dissipation phase. unsteadiness flow field mainly appears phase as a consequence secondary leakage. There primary caused (TLF), these related to each other feedback...

A Lagrangian method is introduced to analyze the tip leakage vortex (TLV) behavior in a low-speed axial compressor rotor. The finite-time Lyapunov exponent (FTLE) fields are calculated based on delayed detached-eddy simulation (DDES) results and identifying FTLE ridges as coherent structures (LCSs). computational of field three-dimensional unsteady flow discussed then applied instantaneous at both design near-stall conditions. Results show that accuracy particle trajectory density initial...

Forced convection heat transfer plays a vital role in engineering; however, its control presents significant complexity. In this paper, closed-loop deep reinforcement learning framework is introduced to optimize cooling tasks exchanger, where cylindrical source immersed narrow cavity. The online Q-networks (DQN) algorithm implemented, and an offline conservative Q-learning soft actor-critic (CQL-SAC) first proposed learn based solely on preexisting databases without interacting with the...

Numerical simulations have been carried out to investigate the effect of moving end wall on tip leakage flow structure in a compressor cascade with four different clearance heights. A detailed comparison flow’s loss; mass rate; and vortex its roll-up, trajectory, size, interaction passage was made. The results show that performance changes more severely as height increases than stationary wall. roll-up has studied by analyzing pathline vorticity distribution. An alternative explanation is...

Abstract The standard k-ε model (SKE) and the Reynolds stress (RSM) are employed to predict tip leakage flow (TLF) in a low-speed large-scale axial compressor rotor. Then, new research method is adopted “freeze” turbulent kinetic energy dissipation rate of field derived from RSM, obtain viscosity using Boussinesq hypothesis. stresses mean computed on basis frozen compared with results SKE RSM. region based more similar RSM than those SKE, although certain differences can be observed. This...

Cavitation significantly impacts the performance of hydraulic machinery. However, cavitation is complex, and evolution complex vortical structures in cavitating flow requires further investigation. In this study, unsteady around a NACA0009 hydrofoil with gap sizes 1 10 mm simulated using grid-adaptive simulation (GAS), which novel hybrid method that modifies turbulent viscosity based on Kolmogorov energy spectrum. The prediction accuracy GAS validated by comparing experimental LES results,...

Tip leakage flow (TLF) is an important structure in the compressor, and it has a significant effect on efficiency stability of compressor. In this study, dynamic mode decomposition (DMD) used to study spatiotemporal tip compressor rotor. The high-fidelity field calculated via delayed-detached eddy simulation (DDES) axial rotor as input dataset for DMD algorithm. results show that unsteady motion vortex (TLV) quite different at its generation, development, dissipation phases. Additionally,...

Abstract Numerical simulations are carried out to investigate the effect of sloped trench casing treatment on performance and stability a compressor cascade, an isolated rotor, single stage. The research objects alter from simplified flow model actual working environment. Firstly, detailed study how effects tip leakage structure, especially vortex is presented. Results show that strength weakened as transforms structure vortex. Then simulation results rotor stage studied. For both cases,...

Tip leakage flow (TLF) is an important structure in the compressor, and it has a significant effect on efficiency stability of compressor. In our study, dynamic mode decomposition (DMD) used to study spatiotemporal tip compressor rotor. The high-fidelity field calculated via delayed-detached eddy simulation (DDES) axial rotor as input dataset for DMD algorithm. results show that unsteady motion vortex (TLV) quite different at its generation, development, dissipation phases. Additionally,...

Cavitation significantly impacts the performance of hydraulic machinery. However, cavitation is complex, and evolution complex vortical structures in cavitating flow requires further investigation. In this study, unsteady around a NACA0009 hydrofoil with gap sizes 1 mm 10 simulated using grid-adaptive simulation (GAS), which novel hybrid method that modifies turbulent viscosity based on Kolmogorov energy spectrum. The prediction accuracy GAS validated by comparing experimental LES results,...