scholarly journals Meander-Like Shape Optimization of the Stator-Rotor Platform Cavity

2018 ◽  
Author(s):  
Paht Juangphanich ◽  
Guillermo Paniagua
Keyword(s):  
Geometry Optimization ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Practical Implementation ◽  
Computational Domain ◽  
Optimization Strategy ◽  
Minimum Thickness ◽  
Ansys Fluent ◽  
Driving Mechanisms ◽  
Wide Range

Recent progress in additive manufacturing has enabled opportunities to explore novel stator rim geometries which can be implemented to improve cooling strategies in turbomachinery. This paper presents a simplified stationary geometry optimization strategy to produce enhanced stator-rotor cavity sealing and highlights main driving mechanisms. The stator and rotor rims were designed using a design strategy based on inspiration from the meandering of rivers. A minimum thickness of 2mm was maintained throughout the cavity to ensure a practical implementation. The computational domain comprised of the stator outlet, hub disk leakage cavity, and rotor platform was meshed using NUMECA Int. package, Hexpress. The numerical analysis required 3D Unsteady Reynolds Average Navier-Stokes to replicate vorticial structures using Ansys Fluent. The operating conditions were representative of engine-like conditions, exploring a wide range of massflow ratios from 1 to 3%. The optimization yielded designs that provide 30% reduction in rear platform temperature while minimizing coolant massflow. The applicability of the design was compared against 3D sector in both stationary and in rotation.

Numerical Research of the Effect of the Outlet Diameter of Diffuser on the Performance and the Radial Force in a Single-Stage Centrifugal Pump

2014 ◽  
Author(s):  
Jiang Wei ◽  
Li Guojun ◽  
Liu Pengfei ◽  
Zhang Lisheng ◽  
Qing Hongyang
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Numerical Results ◽  
Operating Conditions ◽  
Single Stage ◽  
Navier Stokes ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Vaned Diffuser ◽  
Unsteady Numerical Simulation

In this paper, a single-stage pump with diffuser vanes of different outlet diameters has been investigated both numerically and experimentally. The influence of the diffuser vane outlet diameter on pump hydraulic performance and on the radial force of the impeller is explored. Pumps equipped with three different diffusers but with impellers and volutes of the same parameters were simulated by 3D Navier-Stokes solver ANSYS-FLUENT in order to study the effect of the outlet diameter of vaned diffuser on performance of the centrifugal pump. Structured grids of high quality were applied on the whole computational domain. Experimental results were acquired by prototype experiments and were then compared with the numerical results. Both experimental and numerical results show that the performance of a pump with a diffuser of smaller outlet diameter is better than of bigger outlet diameter under all operating conditions. The radial force imposed on the impeller obtained by unsteady numerical simulation was analyzed. The results also indicated that an appropriate decrease in the outlet diameter of the diffuser vane could increase the radial force.

scholarly journals WAVE PRESSURE DISTRIBUTIONS ON A U-OWC BREAKWATER: EXPERIMENTAL DATA VS CFD MODEL

2018 ◽  
pp. 15
Author(s):  
Pasquale G. Fabio Filianoti ◽  
Luana Gurnari
Keyword(s):  
Pressure Distribution ◽  
High Performance ◽  
Ideal Gas ◽  
Navier Stokes ◽  
Eastern Coast ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Wave Energy Converters ◽  
Vof Model ◽  
Line Force

U-OWCs are Wave Energy Converters belong in to the family of Oscillating Water Column. The interaction between waves and a U-OWC breakwater produces an unknown pressure distribution on the breakwater wall, due to the motion inside the plant. In order to evaluate the force acting on a U-OWC breakwater produced by regular waves, we carried out an experiment in a 2D numerical flume. The computational domain is equipped by a piston-type wavemaker, in the left extremity side and a U-OWC breakwater on the opposite side. The water-air interaction is taken into account by means of the Volume Of Fluid (VOF) model implemented in the commercial CFD code Ansys Fluent. Both air and water flow fields are assumed to be unsteady and are computed by solving the Reynolds-Averaged Navier-Stokes (RANS) equations. In the numerical model, air is considered as an ideal gas, in order to take into account the compressibility inside the plenum chamber. Results were compared with a theoretical model on a traditional vertical breakwater and experimental results obtained through an experiment directly at sea, off the beach of Reggio Calabria, in the eastern coast of the Straits of Messina (Southern Italy). As observed in the physical experiment at sea, the pressure distribution are strongly influenced by the absorption of the plant. Indeed, in case of high performance of the U-OWC, we found a deformation of the pressure distribution in respect to the theoretical one, especially near the outer opening of the plant. This deformation produces a lower in line force on the structure.

Steady and Unsteady Modeling for Heat Transfer Predictions of High Pressure Turbine Blade Internal Cooling

2012 ◽  
Author(s):  
Rémy Fransen ◽  
Nicolas Gourdain ◽  
Laurent Y. M. Gicquel
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Cooling System ◽  
Transfer Problem ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Wall Region ◽  
Internal Cooling ◽  
Computational Domain ◽  
Complex Flow

This work focuses on numerical simulations of flows in blade internal cooling system. Large Eddy Simulation (LES) and Reynolds-Averaged Navier Stokes (RANS) approaches are compared in a typical blade cooling related problem. The case is a straight rib-roughened channel with high blockage ratio, computed and compared for both a periodic and full spatial domains. The configuration was measured at the Von Karman Institute (VKI) using Particle Image Velocimetry (PIV) in near gas turbine operating conditions. Results show that RANS models used fail to predict the full evolution of the flow within the channels where massive separation and large scale unsteady features are evidenced. In contrast LES succeeds in reproducing these complex flow motions and both mean and fluctuating components are clearly improved in the channels and in the near wall region. Periodic computations are gauged against the spatial computational domain and results on the heat transfer problem are addressed.

Application of an Improved Streamline Curvature Approach to a Modern, Two-Stage Transonic Fan: Comparison With Data and CFD

2002 ◽  
Author(s):  
Keith M. Boyer ◽  
Walter F. O’Brien
Keyword(s):  
Three Dimensional ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Model Parameters ◽  
Two Stage ◽  
Streamline Curvature ◽  
Wide Range ◽  
Improved Model ◽  
Transonic Fan ◽  
Streamline Curvature Method

A streamline curvature method with improvements to key loss models is applied to a two-stage, low aspect ratio, transonic fan with design tip relative Mach number of approximately 1.65. Central to the improvements is the incorporation of a physics-based shock model. The attempt here is to capture the effects of key flow phenomena relative to the off-design performance of the fan. A quantitative analysis regarding solution sensitivities to model parameters that influence the key phenomena over a wide range of operating conditions is presented. Predictions are compared to performance determined from overall and interstage measurements, as well as from a three-dimensional, steady, Reynolds-averaged Navier-Stokes method applied across the first rotor. Overall and spanwise comparisons demonstrate that the improved model gives reasonable performance trending and generally accurate results. The method can be used to provide boundary conditions to higher-order solvers, or implemented within novel approaches using the streamline curvature method to explore complex engine-inlet integration issues, such as time-variant distortion.

Viscous Flow Analysis in Mixed Flow Rotors

1980 ◽  
Vol 102 (1) ◽  
pp. 193-201 ◽  
Author(s):  
I. Khalil ◽  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Viscous Flow ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Laminar Flows ◽  
Operating Conditions ◽  
Field Analysis ◽  
Navier Stokes ◽  
Stream Channels ◽  
Wide Range

A method for analyzing the viscous flow through turbomachine rotors is presented. The field analysis is based on the solution of the full Navier-Stokes equations over the rotor blade-to-blade stream channels. An Alternating-Direction-Implicit method is employed to carry out the necessary numerical integration of the elliptic governing equations. The flow analysis may be applied to various types of turbomachine rotors. Preliminarily, only the case of laminar flows are considered in this paper. The flow characteristics within the rotors of a radial inflow turbine and a radial bladed compressor are investigated over a wide range of operating conditions. Excellent results are obtained when compared with existing experimental data. The method of this analysis is quite general and can deal with wide range of applications. Possible modification of the present study to deal with turbulent flow cases are also identified.

Analytical Maps of Aerodynamic Damping as a Function of Operating Condition for a Compressor Profile

2006 ◽  
Author(s):  
Paul J. Petrie-Repar ◽  
Andrew McGhee ◽  
Peter A. Jacobs ◽  
Rowan Gollan
Keyword(s):  
Inviscid Flow ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Operating Condition ◽  
Flow Solver ◽  
Aerodynamic Damping ◽  
Wide Range ◽  
Contour Plots ◽  
Standard Configuration

In this paper, analytical maps of aerodynamic damping for a two-dimensional compressor cascade (Standard Configuration 10) are presented. The maps are shown as contour plots of the aerodynamic damping as a function of operating condition. The aerodynamic dampings were calculated by a linearized Navier-Stokes flow solver. The flutter boundaries over a wide range of operating conditions are clearly shown on the damping maps and were found to be strongly dependent on the mode frequency and the mode shape. Extremely low values of negative aerodynamic damping were predicted for some off-design operating conditions where flow separation occurred. A damping map was also constructed based on inviscid flow simulations. There were differences in the viscous and inviscid flutter boundaries particularly at off-design inflow angles. The extremely low values of negative aerodynamic damping were only predicted by the viscous simulations and not the inviscid simulations.

Predicted Effects of Bearing Sump and Injection Pressures on Oil Labyrinth Leakage

2002 ◽  
Vol 125 (1) ◽  
pp. 316-325 ◽  
Author(s):  
S.-Y. Park ◽  
D. L. Rhode
Keyword(s):  
Injection Pressure ◽  
Computer Code ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Vapor Flow ◽  
Buffer Gas ◽  
Labyrinth Seals ◽  
Process Gas ◽  
New Information ◽  
Wide Range

New information and an enhanced understanding concerning the oil vapor contaminant leaking through nonflooded oil labyrinth seals are provided. The results were obtained using a finite volume Navier-Stokes computer code that was extended to include the concentration transport equation. The minimum (i.e., critical) pressure and flow rate at which uncontaminated buffer gas must be injected to prevent oil vapor from leaking to the process gas was determined for a range of seal geometries and operating conditions. It was found that the variation of the critical buffer-gas injection pressure with bearing gas and process gas pressures, for example, was surprisingly small for the cases considered. In addition, the bearing gas and oil vapor flow rates for a wide range of bearing and injection (where present) pressures and geometries were determined for both buffered as well as nonbuffered seals.

scholarly journals Development and validation of a reduced mechanism for methane using a new integral algorithm in a premixed flame

2014 ◽  
Vol 68 (5) ◽  
pp. 529-539
Author(s):  
Zuozhu Wu ◽  
Xinqi Qiao ◽  
Zhen Huang
Keyword(s):  
Reduction Process ◽  
Operating Conditions ◽  
Computational Domain ◽  
Fast Reaction ◽  
One Dimensional ◽  
Reduced Mechanism ◽  
Wide Range ◽  
Computational Singular Perturbation ◽  
Premixed Laminar ◽  
Development And Validation

A new algorithm based on Computational Singular Perturbation (CSP) is proposed to construct global reduced mechanism. The algorithm introduces species concentrations, species net production rates and heat release rates as integral weighting factors to integrate CSP-pointers, including radical pointers and fast reaction pointers, throughout the computational domain. A software package based on the algorithm was developed to make the reduction process more efficient. Input to the algorithm includes (i) the detailed mechanism, (ii) the numerical solution of the problem for a specific set of operating conditions, (iii) the number of quasi steady state (QSS) species. The proposed algorithm was applied to the reduction of GRI3.0 involving 53 species and 325 reactions leading to the development of a 15-species reduced mechanism with 10 lumped steps. Then the reduced mechanism was validated in a one-dimensional, unstretched, premixed, laminar steady flame over a wide range of equivalence ratio, and excellent agreements between results calculated with the detailed and the reduced mechanisms can be observed.

Case Studies of Fatigue Failures in Defence Aircraft Components

2014 ◽  
Vol 891-892 ◽  
pp. 81-86 ◽  
Author(s):  
Cathy Smith ◽  
Drew Donnelly
Keyword(s):  
Case Studies ◽  
Failure Modes ◽  
Correct Diagnosis ◽  
Cost Savings ◽  
Operating Conditions ◽  
Driving Mechanisms ◽  
Wide Range ◽  
Australian Defence Force ◽  
Remedial Actions ◽  
Fatigue Failures

Components and systems of military aircraft are regularly subjected to severe operating conditions, which lead to the development of a wide range of failure modes. The Defence Science and Technology Organisations (DSTO) Forensic Engineering and Accident Investigation group investigates such failures for the Australian Defence Force (ADF). Correct diagnosis of these failures has provided the ADF with immediate advice that has contributed to increased aircraft safety, improved operational availability, and significant cost savings. This paper presents a number of case studies of recent fatigue failures which have occurred in Australian Defence aircraft. The case studies include examples of failures which occurred via differing fatigue initiating and driving mechanisms. Details of the forensic investigations relating to each case study are provided and the ensuing remedial actions discussed.

Numerical Investigation and Performance Characterization of Oscillating Foil Energy Harvesting

2020 ◽  
Author(s):  
James Pannell ◽  
D. Keith Walters
Keyword(s):  
Energy Harvesting ◽  
Operating Conditions ◽  
Practical Implementation ◽  
Significant Drop ◽  
Ansys Fluent ◽  
Reduced Frequency ◽  
Energy Harvesting Efficiency ◽  
And Performance ◽  
Oscillating Foil ◽  
Energy Harvesting Devices

Abstract Oscillating foil energy harvesting devices are increasingly being considered as a sustainable energy alternative, especially in rivers and tidal areas. This paper applies CFD to an oscillating foil power generation device in order to explore the effects of pitching amplitude, the ratio of heaving amplitude to chord length, and the reduced frequency to the energy harvesting efficiency. Ansys Fluent 17.2 was used for this study, and the results are compared to experimental results that have been previously documented in the open literature. Configurations examined included pitching amplitudes of 65, 70, 75, and 80 degrees; heaving ratios of 0.4, 0.6, and 0.8; and reduced frequencies of 0.1, 0.12, 0.14, and 0.16. Results seems to indicate that the optimal reduced frequency is related to the heaving ratio, with the pitching amplitude only creating slight variations in the power produced by the foil. In the data, configurations with a heaving ratio of 0.4 have highest efficiency at reduced frequencies of either 0.14 or 0.16, but efficiency remains high at both points, which indicates the possibility of a peak in between the two points. Configurations with heaving ratio of 0.6 peak at reduced frequency 0.14 with a significant drop off at reduced frequency of 0.16. Finally, configurations with a heaving ratio of 0.8 show a peak at 0.12 reduced frequency and a significant drop at 0.14 and 0.16. These results suggest that OFEH devices can be effectively optimized for different and potentially varying operating conditions that may be encountered during practical implementation of OFEH technology.

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