scholarly journals A high-fidelity body-force modeling approach for plasma-based flow control simulations

2021 ◽  
Vol 33 (3) ◽  
pp. 037115
Author(s):  
Di Chen ◽  
Kengo Asada ◽  
Satoshi Sekimoto ◽  
Kozo Fujii ◽  
Hiroyuki Nishida
Keyword(s):  
Flow Control ◽  
Body Force ◽  
High Fidelity ◽  
Modeling Approach ◽  
Force Modeling

A Review of Inlet-Fan Coupling Methodologies

2017 ◽  
Author(s):  
Benjamin Godard ◽  
Edouard De Jaeghere ◽  
Nabil Ben Nasr ◽  
Julien Marty ◽  
Raphael Barrier ◽  
...  
Keyword(s):  
Experimental Data ◽  
Industrial Design ◽  
Body Force ◽  
The Body ◽  
Source Terms ◽  
Force Modeling ◽  
Actuator Disc ◽  
Flow Deviation ◽  
New Challenges ◽  
Bypass Ratio

With the rise of ultra high bypass ratio turbofan and shorter and slimmer inlet geometries compared to classical architectures, designers face new challenges as nacelle and fan design cannot anymore be addressed independently. This paper reviews CFD methods developed to simulate inlet-fan interactions and suitable for industrial design cycles. In addition to the reference isolated fan and nacelle models, the methodologies evaluated in this study consist of two fan modeling approaches, an actuator disc and body-force source terms. The configuration is a modern turbofan with a high bypass ratio under cross-wind. Results are compared to experimental data. As to be predicted, the body-force modeling approach enables early inlet reattachment. In addition, it provides a representative flow deviation across the fan zone which enables performance and stability assessments.

Body Force Modeling of the Aerodynamics of the Fan of a Turbofan at Windmill

2016 ◽  
Author(s):  
Guillaume Dufour ◽  
William Thollet
Keyword(s):  
Experimental Data ◽  
Rotational Speed ◽  
Body Force ◽  
Ground Level ◽  
Cost Ratio ◽  
Present Contribution ◽  
Force Modeling ◽  
Radial Profiles ◽  
Bypass Ratio ◽  
Good Agreement

The windmilling regime of a turbofan corresponds to a freewheeling mode of the fan rotor, driven by the ram pressure at the inlet. Early in the design process, determination of the windmilling rotational speed of the fan can be critical in the design of the supporting structure of the engine. Therefore, prediction of key parameters in windmilling is an important part of engine design. In particular, given the very high bypass ratio obtained at windmill (typically around 50), the flow in the fan stage and bypass duct is of prime interest, as it drives the establishment of the rotational speed of the low pressure spool and the overall drag. Classical CFD simulations have been shown to provide an adequate representation of the flow, but extensive parametric studies can be needed, which underlines the need for reduced-cost modeling of the flow in the engine. In this context, a body force modeling (BFM) approach to windmilling simulations is examined in the present contribution. The main objective is to assess the capability of the BFM approach to reproduce the aerodynamics of the flow in the fan rotor of a turbofan at windmill, and to propose a method to predict the rotational speed of the fan. The test case considered is a high-bypass ratio geared turbofan (the DGEN 380), which has been tested in an experimental facility designed to reproduce ground level windmilling conditions. The available global and local experimental data are used to validate the model. Furthermore, classical RANS simulations are also provided as reference simulations to assess the accuracy of the BFM results. It is found that the overall performance of the fan is well predicted by the BFM simulations, in particular at the low rotational regime associated to windmilling. In terms of local validation, radial profiles are also found to be in good agreement, except close to the shroud. Analysis of the CFD results shows this can be traced back to massive flow separation in the rotor tip area. In terms of cost, a BFM simulation is about 80 times faster than the baseline CFD computation, making this approach very efficient in term of accuracy-to-cost ratio. Finally, assuming zero-work exchange across the rotor, a transient equation for the rotational speed is derived and included in the time-marching process to the steady state. As a result, the rotational speed of the fan becomes an output of the simulations. The rotational speed predicted by the present model shows good agreement with engine experimental data. However, as only the rotor is modeled, the internal losses are not fully accounted for, and the massflow has to be specified from the experimental data. Further improvement of the approach will consist in modeling the stator and the complete secondary duct so that the loss, and therefore the massflow, can be predicted.

Estimation of Resistance and Self-Propulsion Characteristics fc Low L/B Twin-Skeg Container Ship by a High-Fidelity RANS Solver

2013 ◽  
Vol 57 (01) ◽  
pp. 24-41
Author(s):  
Nobuaki Sakamoto ◽  
Yasutaka Kawanami ◽  
Shotaro Uto ◽  
Noriyuki Sasaki
Keyword(s):  
High Performance ◽  
Single Phase ◽  
Body Force ◽  
Design Tool ◽  
Computational Method ◽  
Navier Stokes ◽  
High Fidelity ◽  
Container Ship ◽  
Finite Volume Discretization ◽  
Performance Computing

Reynolds-averaged Navier-Stokes simulations together with verification and validation studies for a low L/B twin-skeg container ship are carried out using SURF version 6.44, which is a high-fidelity RANS solver for ship hydrodynamics developed at the National Maritime Research Institute: single-phase level set free surface, Spalart-Allmaras/k-co turbulence, and body-force propeller models; finite volume discretization; and parallelized by openMPW for high-performance computing. At the beginning, simulation numerical uncertainty has been quantified for resistance and self-propulsion coefficients on the basis of the standard V&V procedure recommended by the International Towing Tank Conference. Then the resistance and self-propulsion simulations are carried out at several speeds ranging from low to medium Froude numbers. The overall results are encouraging in that the solver accurately predicts resistance and self-propulsion coefficients as well as velocity distribution at the propeller plane in comparison to the available experimental data. Further sophistications in computational method, especially in estimating self-propulsion coefficients, will lead the solver to be more practical and powerful design tool.

scholarly journals New Cutting Force Modeling Approach for Flat End Mill

2007 ◽  
Vol 20 (3) ◽  
pp. 282-288 ◽  
Author(s):  
Min WAN ◽  
Wei-hong ZHANG ◽  
Gang TAN ◽  
Guo-hua QIN
Keyword(s):  
Cutting Force ◽  
End Mill ◽  
Modeling Approach ◽  
Force Modeling
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