scholarly journals Probabilistic Performance Analysis of Eroded Compressor Blades

2005 ◽  
Author(s):  
A. Kumar ◽  
P. B. Nair ◽  
A. J. Keane ◽  
S. Shahpar
Keyword(s):  
Probabilistic Analysis ◽  
Surrogate Model ◽  
Uncertainty Propagation ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Compressor Blades ◽  
Geometry Modeling ◽  
Blade Section ◽  
Computational Fluid Dynamics Cfd ◽  
Fan Blade

This paper presents a probabilistic analysis of the effect of erosion on the performance of compressor fan blades. A realistic parametric CAD model is developed to represent eroded blades. Design of Experiments (DOE) techniques are employed to generate a set of candidate points, which are combined with a parametric geometry modeling and grid generation routine to produce a hybrid mesh. A multigrid Reynolds-Averaged Navier Stokes (RANS) solver HYDRA with Spalart Allmaras turbulence model is used for Computational Fluid Dynamics (CFD) simulations. The data generated is used to create a surrogate model for efficient uncertainty propagation. This method is applied to a typical Rolls Royce compressor fan blade section. Monte Carlo Simulation, using the surrogate model, is executed for the probabilistic analysis of the compressor fan blade. Results show upto 5% increase in pressure loss for the eroded compressor fan blades.

scholarly journals Robust Design of Compressor Fan Blades Against Erosion

2006 ◽  
Vol 128 (4) ◽  
pp. 864-873 ◽  
Author(s):  
Apurva Kumar ◽  
Andy J. Keane ◽  
Prasanth B. Nair ◽  
Shahrokh Shahpar
Keyword(s):  
Mean Shift ◽  
Optimal Solution ◽  
Compressor Blades ◽  
Geometry Modeling ◽  
Numerical Studies ◽  
Blade Section ◽  
Mean And Variance ◽  
The Mean ◽  
Computational Budget ◽  
Fan Blade

This paper is concerned with robust aerodynamic design of compressor blades against erosion. The proposed approach combines a multiobjective genetic algorithm with geometry modeling methods, high-fidelity computational fluid dynamics, and surrogate models to arrive at robust designs on a limited computational budget. The multiobjective formulation used here allows explicit trade-off between the mean and variance of the performance to be carried out. Detailed numerical studies are presented for robust geometric design of a typical compressor fan blade section to illustrate the proposed methodology. The performance of a selected robust optimal solution on the Pareto front is compared to a deterministic optimal solution to demonstrate that significant improvements in the mean shift and variance can be achieved.

Evaluation of Aerodynamic Characteristics of Mega-Yacht Superstructures by CFD Simulations

2020 ◽  
Vol 36 (04) ◽  
pp. 259-270
Author(s):  
Ahmet Ziya Saydam ◽  
Serhan Gokcay ◽  
Mustafa Insel
Keyword(s):  
Aerodynamic Characteristics ◽  
Temperature Gradients ◽  
Time Dependent ◽  
Navier Stokes ◽  
Noise Generation ◽  
Velocity Data ◽  
Cfd Simulations ◽  
Recent Developments ◽  
Computational Fluid Dynamics Cfd

Air wake distribution around the superstructure of a mega-yacht is a key concern for the designer because of various reasons such as comfort expectations in recreational deck areas, self-noise generation, air pollution and temperature gradients due to exhaust interactions, and safety of helicopter operations such as landing/take off and hovering. The Reynolds-averaged Navier-Stokes (RANS) technique in computational fluid dynamics (CFD) is frequently used in studies on mega-yacht hydrodynamics and aerodynamics with satisfactory results. In this article, a case study is presented for the utilization of CFD in a mega-yacht's superstructure design. The flow field in recreational open areas has been analyzed for the increase in velocity due to the existence of the superstructure. A reduction in self-noise of the mast structure has been aimed by reducing flow separation and vorticity. Time-dependent velocity data obtained with scale-resolving simulations are presented for the evaluation of helicopter landings. The capabilities and limitations of the RANS technique are discussed along with recent developments in modeling approaches.

scholarly journals The Efficient Application of an Impulse Source Wavemaker to CFD Simulations

2019 ◽  
Author(s):  
Pál Schmitt ◽  
Christian Windt ◽  
Josh Davidson ◽  
John V. Ringwood ◽  
Trevor Whittaker
Keyword(s):  
Shallow Water ◽  
Source Function ◽  
Cfd Simulation ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Wide Range ◽  
Rans Models ◽  
Hydrodynamic Processes ◽  
Computational Fluid Dynamics Cfd ◽  
Shallow Water Models

Computational Fluid Dynamics (CFD) simulations, based on Reynolds Averaged Navier Stokes (RANS) models, are a useful tool for a wide range of coastal and offshore applications, providing a high fidelity representation of the underlying hydrodynamic processes. Generating input waves in the CFD simulation is performed by a numerical wavemaker (NWM), with a variety of different NWM methods existing for this task. While NWMs, based on impulse source methods, have been widely applied for wave generation in depth averaged, shallow water models, they have not seen the same level of adoption in the more general RANS based CFD simulations, due to difficulties in relating the required impulse source function to the resulting free surface elevation for non-shallow water cases. This paper presents an implementation of an impulse source wavemaker, which is able to self-calibrate the impulse source function to produce a desired wave series in deep or shallow water at a specific point in time and space. Example applications are presented, for a numerical wave tank (NWT), based on the opensource CFD software OpenFOAM, for wave packets in deep and shallow water, highlighting the correct calibration of phase and amplitude. Also, the suitability for cases requiring very low reflection from NWT boundaries is demonstrated. Possible issues in the use of the method are discussed and guidance for good application is given.

Comparison of the CFD Results to PIV Measurements in Kinematics of Spilling and Plunging Breakers

2020 ◽  
Author(s):  
Bülent Düz ◽  
Jule Scharnke ◽  
Rink Hallmann ◽  
Jan Tukker ◽  
Siddhant Khurana ◽  
...  
Keyword(s):  
High Speed ◽  
Piecewise Linear ◽  
Sampling Rate ◽  
Navier Stokes ◽  
Computational Domain ◽  
Cfd Simulations ◽  
High Sampling Rate ◽  
Interface Reconstruction ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd

Abstract The kinematics under spilling and plunging breakers are investigated using both experimental and numerical methods. In a modular laboratory flume, the breakers were generated using dispersive focusing, and the kinematics underneath them were measured utilizing the Particle Image Velocimetry (PIV) technique. Using the state-of-art high-speed video cameras and lasers, the kinematics were measured at a high sampling rate without needing phase-locked averaging. Afterwards, Computational Fluid Dynamics (CFD) simulations were carried out for comparison purposes. These simulations were run in single-phase using a finite-volume based Navier-Stokes solver with a piecewise-linear interface reconstruction scheme. The spilling and plunging breakers from the measurements were reconstructed in the computational domain using an iterative scheme. As a result a good match with the measured waves was obtained in the simulations. Results indicate that even though measured kinematics are somewhat higher than the simulated ones especially in the spilling and overturning regions, the CFD simulations can accurately capture the relevant details of the flow and produce reasonably accurate kinematics in comparison with the PIV results.

Hybrid LES Approach for Practical Turbomachinery Flows—Part II: Further Applications

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Paul Tucker ◽  
Simon Eastwood ◽  
Christian Klostermeier ◽  
Hao Xia ◽  
Prasun Ray ◽  
...  
Keyword(s):  
Navier Stokes ◽  
Jet Flows ◽  
Hybrid Strategy ◽  
Eddy Simulation ◽  
Wall Flows ◽  
Large Eddy ◽  
Blade Section ◽  
Transition Modeling ◽  
Fan Blade ◽  
Les Model

A hybrid large eddy simulation (LES) related technique is used to explore some key turbomachinery relevant flows. Near wall Reynolds-averaged Navier-Stokes (RANS) modeling is used to cover over especially small scales, the LES resolution of which is generally intractable with current computational power. Away from walls, large eddy type simulation is used but with no LES model (numerical LES (NLES)). Linking of the two model zones through a Hamilton–Jacobi equation is explored. The hybrid strategy is used to predict turbine and compressor end wall flows, flow around a fan blade section, jet flows, and a cutback trailing edge. Also, application of NLES to the flow in an idealized high pressure compressor drum cavity is considered. Generally, encouraging results are found. However, challenges remain, especially for flows where transition modeling is important.

Gas Flow Simulations in Randomly Distributed Pebbles

2010 ◽  
Author(s):  
Xiang Zhao ◽  
Trent Montgomery ◽  
Sijun Zhang
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Flow Fields ◽  
Navier Stokes ◽  
Complex Flow ◽  
Flow Simulations ◽  
Geometry Modeling ◽  
Eddy Simulation ◽  
Rans Models ◽  
Computational Fluid Dynamics Cfd

In this paper, computational fluid dynamics (CFD) gas flow simulations are carried out. In CFD calculations, geometry modeling and physical modeling are crucial to CFD results. The effects of the treatments of the inter-pebble contacts on gas flow fields and heat transfer are examined; a sensitivity analysis for the gap size is conducted with two spherical pebbles, in which the inter-pebble region is modeled by means of two types of inter-pebble gaps and two kinds of direct contacts. On the other hand, both of large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) models are employed to investigate the turbulent effects. It is found that the flow fields and relevant heat transfer are significantly dependent on the modeling of the inter-pebble regions. The calculations indicate the complex flow structures present within the voids between the fuel pebbles.

A Study of Wind Turbine Wakes in Complex Terrain Through RANS Simulation and SCADA Data

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Davide Astolfi ◽  
Francesco Castellani ◽  
Ludovico Terzi
Keyword(s):  
Wind Turbine ◽  
Complex Terrain ◽  
Lateral Displacement ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Test Case ◽  
Cfd Simulations ◽  
Relevant Role ◽  
Computational Fluid Dynamics Cfd

This work deals with wind turbine wakes in complex terrain. The test case is a cluster of four 2.3 MW wind turbines, sited in a very complex terrain. Their performances are studied through supervisory control and data acquisition (SCADA) data, suggesting a relevant role of the terrain in distorting the wake of the upstream turbines. The experimental evidences stimulate a deeper comprehension through numerical modeling: computational fluid dynamics (CFD) simulations are run, using the Reynolds-averaged Navier–Stokes (RANS) formulation. A novel way of elaborating the output of the simulations is proposed, providing metrics for quantifying the three-dimensional (3D) evolution of the wake. The main outcome of the numerical analysis is that the terrain distorts the wind flow so that the wake profile is severely asymmetric with respect to the lateral displacement. Further, the role of orography singularities is highlighted in dividing the wake front, thus inducing faster wake recovery with respect to flat terrain. This interpretation is confirmed by SCADA data analysis.

Approach for uncertainty propagation and design in Saint Venant equations via automatic sensitive derivatives applied to Saar river

2009 ◽  
Vol 36 (7) ◽  
pp. 1144-1154 ◽  
Author(s):  
Otmane Souhar ◽  
Jean-Baptiste Faure
Keyword(s):  
Automatic Differentiation ◽  
Divided Difference ◽  
Uncertainty Propagation ◽  
Free Surface Flows ◽  
Cfd Simulations ◽  
Surface Flows ◽  
One Dimensional ◽  
Saint Venant Equations ◽  
Computational Fluid Dynamics Cfd ◽  
Derivatives Of

This paper describes the assessment of uncertainties of computational fluid dynamics (CFD) for modelling free surface flows. A series of CFD simulations, using MAillé GEnéralisé (MAGE), are employed to compute the flood extent resulting from the overflow of rivers. These simulated outputs are affected by uncertainties in the empiric roughness coefficients. Uncertainty propagation in MAGE outputs is difficult to evaluate because of the complexity and the nonlinearity of models. Assessment of uncertainties may be carried out by computing derivatives of the output results with respect to the inputs. Recently, automatic differentiation (AD) has become an efficient numerical method for sensitivity analysis and assessment of uncertainties. In this paper, AD is used to transform mechanically a given one-dimensional hydraulic model, MAGE, into a new program capable of computing the original simulation and the desired derivatives. Specifically, derivatives of the flood extent and the water width with respect to the roughness coefficients are computed. Numerical experiments of derivatives obtained from AD and divided difference (DD) approximations are compared, validating derivatives obtained by AD. Results can serve to evaluate existing flood models.

Gas Flow Simulations in Randomly Distributed Pebbles

2010 ◽  
Vol 133 (5) ◽  
Author(s):  
Xiang Zhao ◽  
Trent Montgomery ◽  
Sijun Zhang
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Flow Fields ◽  
Navier Stokes ◽  
Complex Flow ◽  
Pebble Bed Reactor ◽  
Flow Simulations ◽  
Geometry Modeling ◽  
Eddy Simulation ◽  
Computational Fluid Dynamics Cfd

In this paper, computational fluid dynamics (CFD) gas flow simulations are carried out for the pebble bed reactor. In CFD calculations, geometry modeling and physical modeling are crucial to CFD results. The effects of the treatments of the interpebble contacts on gas flow fields and heat transfer are examined. A sensitivity analysis for the gap size is conducted with two spherical pebbles, in which the interpebble region is modeled by means of two types of interpebble gap and two kinds of direct contact. Both large eddy simulation and Reynolds-averaged Navier–Stokes models are employed to investigate the turbulent effects. It is found that the flow fields and relevant heat transfer are significantly dependent on the modeling of the interpebble region. The calculations indicate the complex flow structures present within the voids between the fuel pebbles.

Study on the Fuel Flexibility of a Microgas Turbine Combustor Burning Different Mixtures of H2, CH4, and CO2

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Antonio Di Nardo ◽  
Alessandro Bo ◽  
Giorgio Calchetti ◽  
Eugenio Giacomazzi ◽  
Giuseppe Messina
Keyword(s):  
Laminar Flame ◽  
Fuel Mixture ◽  
Combustion Efficiency ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Fuel Flexibility ◽  
Partial Load ◽  
3D Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Wobbe Index

Abstract The aim of this work is to analyze the behavior of the fuel flexible Ansaldo ARI100 T2 microgas turbine (MGT) combustor operated with mixtures having different H2, CH4, and CO2 concentrations. This combustor is going to be installed on an in-house modified Turbec T100 P MGT, which is originally equipped with a methane fired combustor. In a previous study, the combustor was simulated with a H2 enriched syngas, whose Wobbe index was within the limits imposed by the syngas supply system of an Ansaldo test bench. In this study, this constraint has been removed to gain a deeper understanding on how the fuel mixture properties (composition, heating value, and laminar flame speed) affect combustor performance. To this end, a series of Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations have been carried out on the full-scale 3D geometry of the combustion chamber, at full and partial load (50%), evaluating for each case combustion efficiency as well as NOx and CO emissions.

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