Effects of rotor solidity and leakage flow on the unsteady flow in axial turbine

Gao, Keke; Xie, Yonghui; Zhang, Di

doi:10.1016/j.applthermaleng.2017.09.078

Cited by 18 publications

(6 citation statements)

References 25 publications

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“…The RNG (Re-Normalization Group) k-ε turbulence model, as well as the scalable wall function, were used to solve the turbulence characteristics. On one hand, RNG k-ε model has a higher precision and a faster convergence speed compared to the standard k-ε model, and it has been validated in many studies [20,21]. On the other hand, it demands a relatively high y+ value compared to the SST (Shear Stress Transfer) model, which is more suitable for mesh movement.…”

Section: Computational Methods and Boundary Conditionsmentioning

confidence: 99%

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Pan

Huang

et al. 2020

Applied Sciences

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The purpose of this study was to investigate the characteristics of the blade tip excitation forces represented as the rotordynamic coefficients (stiffness and damping coefficients) in an unshrouded turbine using the three-dimensional computational fluid dynamic (CFD) numerical method. The blade geometrical parameters were based on a SNECMA transonic experimental rig. The simulations were performed by solving the compressible Reynolds-averaged Navier–Stokes (RANS) equations. The multi-frequency elliptical whirling orbit model and an improved mesh deformation method based on the transient analysis were utilized. The effects of operating conditions on the rotordynamic coefficients and the unsteady flow were also found. The results show that the positive direct stiffness, which confirmed the direct force contribution in the tip excitation forces and the cross-coupling stiffness, were dependent on the whirling frequencies. Damping effects were shown to be negligible. The rotational speed, inlet flow angle, eccentric ratio (ER), and mean tip clearance had impacts on the stiffness, and some effects of these variables on the rotordynamic coefficients were found to be frequency dependent. Additionally, increasing the rotor eccentricity and the mean tip clearance led to the nonuniformity of the circumferential pressure distributions.

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Section: Computational Methods and Boundary Conditionsmentioning

confidence: 99%

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Pan

Huang

et al. 2020

Applied Sciences

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“…The recommended value for the aspect ratio, which is the ratio of the height to the chord length of the blade, is between 1.0 and 2.0 for a typical turbine stage [29]. Blade solidity (σ) denotes the ratio of the chord length to the pitch of the blade, and the ideal σ for optimum efficiency ranges approximately from 1.2 to 1.8 [30,31]. The Zweifel coefficient (Z) is the ratio of the actual tangential force to the ideal force acting on the blade.…”

Section: Flow Chart Of the Turbine Designmentioning

confidence: 99%

Performance Analysis of Organic Rankine Cycle with the Turbine Embedded in a Generator (TEG)

2022

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The organic Rankine cycle (ORC) is a thermodynamic cycle in which electrical power is generated using an organic refrigerant as a working fluid at low temperatures with low-grade enthalpy. We propose a turbine embedded in a generator (TEG), wherein the turbine rotor is embedded inside the generator rotor, thus simplifying turbine generator structure using only one bearing. The absence of tip clearance between the turbine rotor blade and casing wall in the TEG eliminates tip clearance loss, enhancing turbine efficiency. A single-stage axial-flow turbine was designed using mean-line analysis based on physical properties, and we conducted a parametric study of turbine performance, and predicted turbine efficiency and power using the tip clearance loss coefficient. When the tip clearance loss coefficient was applied, turbine isentropic efficiency and power were 0.89 and 20.42 kW, respectively, and ORC thermal efficiency was 4.81%. Conversely, the isentropic efficiency and power of the turbine without the tip clearance loss coefficient were 0.94 and 22.03 kW, respectively, and the thermal efficiency of the ORC was 5.08%. Therefore, applying the proposed TEG to the ORC system simplifies the turbine generator, while improving ORC thermal efficiency. A 3D turbine generator assembly with proposed TEG structure was also proposed.

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“…CFD (Computational Fluid Dynamics) investigations played very important role in determining the outcome of the experimental setup and efficiency of the turbine. Software research gave the optimal tip speed ratio and design tip speed ratio [22,[29][30].…”

Section: Experimental Analysis On Axial Flow Turbinementioning

confidence: 99%

The Numerical Simulation and Evaluation of Aircraft Engine Axial Flow Turbine using Numerical Techniques

al.¹

2019

IJMPERD

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This research aims to improve the efficiency of an axial flow turbine by improving the boundary conditions. In the baseline paper, Sherwood number, Nusselts number for a given flow were determined. The pressure ratio was not considered in the paper. Research has been done to improve the values by considering the pressure difference which was neglected in the base line paper. Axial flow turbines expand the flow passing through it. Losses like tip losses, efficiency losses and loss on blades due to heat are high and needs to be looked after. A comprehensive literature study was carried out for the better understanding of axial flow turbines, recent developments and to analyze the control of loses.

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Effects of rotor solidity and leakage flow on the unsteady flow in axial turbine

Cited by 18 publications

References 25 publications

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Numerical Investigations on the Blade Tip Clearance Excitation Forces in an Unshrouded Turbine

Performance Analysis of Organic Rankine Cycle with the Turbine Embedded in a Generator (TEG)

The Numerical Simulation and Evaluation of Aircraft Engine Axial Flow Turbine using Numerical Techniques

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