Numerical Simulation of Erosion in Modified Nozzles of Axial Flow Turbine

2006 ◽  
Author(s):  
Zdzislaw Mazur ◽  
Rafael Campos-Amezcua ◽  
Alfonso Campos-Amezcua
Keyword(s):  
Numerical Simulation ◽  
Solid Particle ◽  
Axial Flow ◽  
Flow Simulation ◽  
Wall Material ◽  
Particle Impact ◽  
Control Stage ◽  
Numerical Predictions ◽  
Erosion Models ◽  
Particles Trajectories

Solid particle erosion in a turbine nozzle (turbine control stage) has been investigated by means of CFD. Literature attempt to couple fluid mechanics and erosion modeling and improvements in the hydrodynamics models together with improvements in the erosion models are reviewed. The solid particle bearing steam flow through the nozzle was investigated using a 3D numerical model and the finite volume code Fluent V6.0.12, looking for a reduction of the erosion process. The flow simulation was carried out for the original and modified (nozzle) designs with changes of the angle of particle impact on the nozzle surface. Numerical predictions have been carried out using the Renormalization Group (RNG) k-ε turbulence mode. To account for the influence of turbulent fluid fluctuations on particle motion, the stochastic tracking Discrete Random Walk model is used, which includes the effect of instantaneous turbulent velocity fluctuations on the particle trajectories. The removal of wall material due to erosion is calculated using the Finnie model developed for ductile materials. The numerical predictions showed a 50 percent reduction of the erosion rate for the modified (nozzle) design due to changes of the particles trajectories and impingement angle (angle of particle impact). The results obtained show that numerical simulation can be used in a predictive manner to solve a real practical design problem.

Numerical Characterization of Hot Gas Ingestion Through Turbine Rim Seals

2016 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Carl M. Sangan ◽  
James A. Scobie ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Buffering Effect ◽  
Hot Gas ◽  
Numerical Predictions ◽  
Wide Range ◽  
Thermal Buffering

This paper deals with a numerical study aimed at the characterization of hot gas ingestion through turbine rim seals. The numerical campaign focused on an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. Single-clearance arrangements were considered in the form of axial- and radial-seal gap configurations. With the radial-seal clearance configuration, CFD steady-state solutions were able to predict the system sealing effectiveness over a wide range of coolant mass flow rates reasonably well. The greater insight of flow field provided by the computations illustrates the thermal buffering effect when ingress occurs: for a given sealing flow rate, the effectiveness on the rotor was significantly higher than that on the stator due to the axial flow of hot gases from stator to rotor caused by pumping effects. The predicted effectiveness on the rotor was compared with a theoretical model for the thermal buffering effect showing good agreement. When the axial-seal clearance arrangement is considered, the agreement between CFD and experiments worsens; the variation of sealing effectiveness with coolant flow rate calculated by means of the simulations display a distinct kink. It was found that the “kink phenomenon” can be ascribed to an over-estimation of the egress spoiling effects due to turbulence modelling limitations. Despite some weaknesses in the numerical predictions, the paper shows that CFD can be used to characterize the sealing performance of axial- and radial-clearance turbine rim seals.

scholarly journals The influence of axial-flow fan trailing edge structure on internal flow

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881174
Author(s):  
Weijie Zhang ◽  
Jianping Yuan ◽  
Banglun Zhou ◽  
Hao Li ◽  
Ye Yuan
Keyword(s):  
Numerical Simulation ◽  
Low Frequency ◽  
Axial Flow ◽  
Internal Flow ◽  
Axial Flow Fan ◽  
Trailing Edge ◽  
Edge Structure ◽  
Blade Loading ◽  
Wideband Noise ◽  
Fluctuation Amplitude

Axial-flow fan with advantages such as large air volume, high head pressure, and low noise is commonly used in the work of air-conditioner outdoor unit. In order to investigate the internal flow mechanism of the axial-flow fan with different trailing edge structures of impellers, four kinds of impellers were designed, and numerical simulation and experiment were deployed in this article. The pressure distribution on the blades surface and distribution of vorticity in impellers were obtained using numerical simulation. Distribution of blade loading and velocity at the circumference are discussed. The relationship between the wideband noise and the trailing edge was established based on the experiment results. The results show that after the optimization of the trailing edge structure, the distribution of vorticity near the trailing edge of the blade is more uniform, especially at the trailing edge of 80% of the chord length of the suction surface. From the blade height position of 70% to the impeller tip, the pressure on the surface rapidly increases due to the tip vortex and the vortex shedding on the blade edge occurred in the top region of impeller. The pressure fluctuation amplitude at the trailing edge structure of the tail-edge optimization structure is smaller. In the distribution of blade loading, the three tail-edge optimization structures have smaller pressure fluctuations and pressure differences at the trailing edge structure. It is extremely important to control the fluctuation amplitude at the trailing edge. The amplitude of low-frequency sound pressure level of optimizing the trailing edge structure decreases obviously in the range of 50–125 Hz, and the optimization structure of trailing edge has an obvious effect on low-frequency wideband noise.

Further Developments in the Aerodynamic Analysis of Unsteady Supersonic Cascades—Part 2: Aerodynamic Response Predictions

1977 ◽  
Vol 99 (4) ◽  
pp. 517-525 ◽  
Author(s):  
J. M. Verdon
Keyword(s):  
Free Stream ◽  
Narrow Range ◽  
Axial Flow ◽  
Stable Condition ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Numerical Predictions ◽  
Free Stream Mach Number ◽  
Parameter Values ◽  
Phase Angles

This paper is the second of a two-part report on a theoretical analysis of the aerodynamic response to an oscillating supersonic cascade in subsonic axial flow. Supersonic resonance criteria are discussed and lead to the distinction between subresonant and superresonant cascade motions. Numerical predictions, based on the unsteady solution reported in Part 1, are presented for two typical cascade configurations. These reveal the possibility of both subresonant and superresonant single-degree-of-freedom torsional instabilities. Subresonant instabilities occur over a broad range of frequencies and interblade phase angles, whereas superresonant instabilities occur only over a narrow range of such cascade parameter values. For a given blade motion frequency and free-stream Mach number, it appears that the least stable condition will usually lie in the subresonant region.

scholarly journals Designing a top cooling system for an electromagnetic calorimeter

2021 ◽  
Vol 345 ◽  
pp. 00015
Author(s):  
Matěj Jeřábek ◽  
Michal Volf ◽  
Daniel Duda
Keyword(s):  
Numerical Simulation ◽  
Pressure Field ◽  
Cooling System ◽  
Flow Simulation ◽  
Electromagnetic Calorimeter ◽  
3D Flow ◽  
Commercial Software ◽  
Pressure Fields ◽  
Detailed Evaluation ◽  
Temperature And Pressure

The article describes a numerical simulation of flow in the cooling system of an electromagnetic calorimeter by analysing the temperature and pressure fields. Two fundamentally different approaches were used to analyse the pressure field - analytical 1D calculation and numerical 3D flow simulation. The article contains a detailed evaluation and description of individual analyses using the commercial software ANSYS 2020 R1.

scholarly journals Study of the Effect of Bulb Ratio and Blade Angle on Propeller Turbine Performance in Horizontal Flow using Numerical Simulation

Teknik ◽  
2020 ◽  
Vol 41 (1) ◽  
pp. 9-13
Author(s):  
Akhmad Nurdin ◽  
Dwi Aries Himawanto ◽  
Syamsul Hadi
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Flow Simulation ◽  
Water Velocity ◽  
Horizontal Flow ◽  
Blade Angle ◽  
Static State ◽  
Turbine Performance ◽  
Solid Works

This paper discusses numerical simulations of horizontal flow propeller turbines. Static bulbs located before the turbine can be used to increase water velocity and potentially increase the turbine's performance. The blade angle affects the gap between the blades, and this will also affect the performance of the turbine. Numerical simulations were conducted by using software Solid Works Flow Simulation 2016 and by using five blades in a static state. This study aimed to determine the effect of the bulb ratio and blade angle on the propeller turbine characteristics on horizontal flow. Bulb Ratio variations used in this study were 0, 0.4, 0.6, and 0.8, while the angle variations used were 20, 25, and 30 degrees. Each variation was tested at 0.02 m3/second. The results of this study indicated that the bulb ratio 0.6 with the 25-degree blade angle produces the highest torque

Full 3-D Unsteady Numerical Simulation of Control Stage in Partial Admission Turbine

2015 ◽  
Vol 741 ◽  
pp. 509-512
Author(s):  
Guo Ping Li ◽  
Ke Ke Gao ◽  
Ke Yang ◽  
Yong Hui Xie
Keyword(s):  
Numerical Simulation ◽  
Surface Pressure ◽  
Flow Parameters ◽  
Control Stage ◽  
Air Turbine ◽  
Unsteady Surface Pressure ◽  
Partial Admission ◽  
Unsteady Numerical Simulation ◽  
Pressure Changes ◽  
Mixing Losses

The unsteady flow parameters in control stage of partial admission are analyzed in details with full 3-D numerical simulation. The full annulus structure of air turbine in partial admission is modeled due to the unsymmetrical geometry. The partial admission is accomplished through the inlet blocked using segmental arc. The unsteady surface pressure changes of eight blades in the transition regions which demonstrate the power output ability are presented. That the entropy rise associated with the losses at different cross mainly caused by mixing losses and flow separation in partial admission is analyzed to estimate the efficiency distribution.

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