Assessment of Body Force Methodologies for the Analysis of Intake-Fan Aerodynamic Interactions

2016 ◽  
Author(s):  
William Thollet ◽  
Guillaume Dufour ◽  
Xavier Carbonneau ◽  
Florian Blanc
Keyword(s):  
Body Force ◽  
The Body ◽  
Test Cases ◽  
Validation Data ◽  
Turbofan Engines ◽  
Force Modeling ◽  
The Cost ◽  
Engine Components ◽  
Bypass Ratio ◽  
Numerical Strategy

With the advent of high bypass ratio turbofan engines of increasing size, new nacelle designs with shorter air intakes have to be considered, creating new aerodynamic interactions with the fan. This paper focuses on a numerical strategy known as Body Force Modeling, in which engine components are modeled and taken into account using source terms in the RANS equation. This approach allows to simulate these interactions with an accuracy comparable to full 360° unsteady simulations, but at a fraction of the cost. Different formulations for the body forces are proposed and applied to different nacelle test cases of varying intake length. Using full annulus unsteady computations as validation data, it is shown that the body force approach allows to capture inlet design effects on in-plane forces and on nacelle flow separation.

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.

scholarly journals Prediction of Crosswind Separation Velocity for Fan and Nacelle Systems Using Body Force Models: Part 1: Fan Body Force Model Generation without Detailed Stage Geometry

2019 ◽  
Vol 4 (4) ◽  
pp. 43 ◽  
Author(s):  
Quentin J. Minaker ◽  
Jeffrey J. Defoe
Keyword(s):  
Design Process ◽  
Body Force ◽  
Pressure Ratio ◽  
Computational Cost ◽  
The Body ◽  
Force Model ◽  
Limited Access ◽  
Turbofan Engines ◽  
Simplifying Assumptions ◽  
Dynamics Simulations

Modern aircraft engines must accommodate inflow distortions entering the engines as a consequence of modifying the size, shape, and placement of the engines and/or nacelle to increase propulsive efficiency and reduce aircraft weight and drag. It is important to be able to predict the interactions between the external flow and the fan early in the design process. This is challenging due to computational cost and limited access to detailed fan/engine geometry. In this, the first part of a two part paper, we present a design process that produces a fan gas path and body force model with performance representative of modern high bypass ratio turbofan engines. The target users are those with limited experience in turbomachinery design or limited access to fan geometry. We employ quasi-1D analysis and a series of simplifying assumptions to produce a gas path and the body force model inputs. Using a body force model of the fan enables steady computational fluid dynamics simulations to capture fan–distortion interaction. The approach is verified for the NASA Stage 67 transonic fan. An example of the design process is also included; the model generated is shown to meet the desired fan stagnation pressure ratio and thrust to within 1%.

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.

scholarly journals The Influence of a Variable Capacity Turbine in the Performance of a Variable Cycle Engine

1999 ◽  
Author(s):  
Martin Dodds ◽  
Pericles Pilidis
Keyword(s):  
Low Pressure ◽  
Variable Geometry ◽  
Variable Flow ◽  
Low Pressure Turbine ◽  
Extensive Variable ◽  
Variable Capacity ◽  
Lp Turbine ◽  
The Cost ◽  
Engine Components ◽  
Bypass Ratio

An investigation was conducted to examine the effects of a variable flow low pressure turbine on a variable cycle engine’s performance. One of the greatest challenges, during the design of a variable cycle engine is how to optimise the various cycles and then to match then to the capabilities of the engine components, the use of extensive variable geometry is required to achieve this. A method of matching variable cycle engines that was developed Cranfield University was adapted to cater for the use of a variable flow low pressure turbine. It was discovered that the implementation of variable geometry within the low pressure turbine could significantly reduce the requirements for variable geometry within the compressor system, at the cost of replacing well proven compressor variable geometry with high risk technology within the LP turbine. Utilising the variable flow turbine to expand the bypass ratio range of the engine was studied. Increasing the LPM bypass ratio to 1.1 and 1.2 yielded SFC reductions of 3% and 5% respectively, reducing the bypass ratio of the HPM to 0.1 gave a 20% increase in specific thrust. It was found that the performance benefits gained from expanding the bypass ratio are large enough to warrant further investigation into this concept.

Improved Hierarchical Modelling for Aerodynamically Coupled Systems

2017 ◽  
Author(s):  
Rob Watson ◽  
Jiahuan Cui ◽  
Yunfei Ma ◽  
James Tyacke ◽  
Nagabhushana Rao Vadlamani ◽  
...  
Keyword(s):  
Body Force ◽  
Cross Flow ◽  
Coupled System ◽  
Coupled Systems ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Blade Row ◽  
Aero Engine ◽  
The Cost ◽  
Engine Components

Strong aerodynamic coupling can make the high fidelity simulation of a number of critical aero-engine components prohibitively expensive — particularly within the timeframes of industrial design cycles. This paper develops a body force based hierarchy of approaches to modelling the effects of blade rows. These are envisaged as allowing the computationally expensive parts of coupled systems to be resolved much more cheaply, rendering the cost of the overall simulation as more manageable. Simulation of the coupling that exists between the flow around an aero-engine intake and its fan is particularly emphasised, as this is becoming stronger and more performance critical with the modern trends towards the reduction of the relative diffuser length. The use of the viscous smeared geometry level of fidelity is initially shown to be an effective model over a number of cases — a simple compressor blade row, a modern high bypass fan, and the Darmstadt rotor. After this, it is shown working as part of a coupled system in an intake experiencing cross-flow. Higher fidelity geometry representations are then considered, which mimic the effect of struts. Finally, a mix of various fidelity geometry representations and turbulence modelling approaches is shown to bring otherwise hugely expensive calculations within the realm of practical computation, in the form of a full fan-to-flap calculation.

scholarly journals Body Force Modeling of the Aerodynamics of a Low-Speed Fan under Distorted Inflow †

2019 ◽  
Vol 4 (3) ◽  
pp. 29 ◽  
Author(s):  
Emmanuel Benichou ◽  
Guillaume Dufour ◽  
Yannick Bousquet ◽  
Nicolas Binder ◽  
Aurélie Ortolan ◽  
...  
Keyword(s):  
Body Force ◽  
Engine Performance ◽  
The Body ◽  
Navier Stokes ◽  
Complex Flows ◽  
Low Speed ◽  
Force Modeling ◽  
Cooling Fan ◽  
Computational Fluid Dynamics Cfd ◽  
Turbomachinery Design

New propulsive concepts, such as boundary layer ingestion, involve stronger interactions between the engine and its environment, and are thus more complex flows compared to classical architectures. Usual turbomachinery design tools are inadequate, and new numerical methodologies are needed to accurately predict the engine performance with affordable CPU resources. The present paper examines the relevance of a reduced-order modeling approach—the body force modeling (BFM) method—for a low-speed cooling fan with inflow distortion. The formulation itself accounts for the blade metal blockage and compressibility effects, and it relies on a semiempirical loss model, independent of computational fluid dynamics (CFD) calibration. The BFM results obtained in the present work are assessed against full-annulus unsteady Reynolds-averaged Navier-Stokes (URANS) results and experiments. The comparison shows that the BFM approach successfully quantifies the fan stage performance. Furthermore, the distortion transfer across the stage is examined and the flow patterns observed are found to be the same as in the URANS results and in the measurements. Hence, this methodology, coming at a low CPU cost, is well-adapted to the early design phase of an innovative propulsion system.

scholarly journals Optimal Implementation of Wastewater Reuse in Existing Sewerage Systems to Improve Resilience and Sustainability in Water Supply Systems

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2004
Author(s):  
Aakash Dev ◽  
Timo C. Dilly ◽  
Amin E. Bakhshipour ◽  
Ulrich Dittmer ◽  
S. Murty Bhallamudi
Keyword(s):  
Wastewater Treatment ◽  
Water Supply ◽  
Wastewater Reuse ◽  
Treated Wastewater ◽  
Water Supply Systems ◽  
Test Cases ◽  
Decentralized Wastewater Treatment ◽  
Graywater Reuse ◽  
The Cost ◽  
Supply Systems

A transition from conventional centralized to hybrid decentralized systems has been increasingly advised recently due to their capability to enhance the resilience and sustainability of urban water supply systems. Reusing treated wastewater for non-potable purposes is a promising opportunity toward the aforementioned resolutions. In this study, we present two optimization models for integrating reusing systems into existing sewerage systems to bridge the supply–demand gap in an existing water supply system. In Model-1, the supply–demand gap is bridged by introducing on-site graywater treatment and reuse, and in Model-2, the gap is bridged by decentralized wastewater treatment and reuse. The applicability of the proposed models is evaluated using two test cases: one a proof-of-concept hypothetical network and the other a near realistic network based on the sewerage network in Chennai, India. The results show that the proposed models outperform the existing approaches by achieving more than a 20% reduction in the cost of procuring water and more than a 36% reduction in the demand for freshwater through the implementation of local on-site graywater reuse for both test cases. These numbers are about 12% and 34% respectively for the implementation of decentralized wastewater treatment and reuse.

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

scholarly journals Roughing Milling with Ceramic Tools in Comparison with Sintered Carbide on Nickel-Based Alloys

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 734
Author(s):  
Pablo Fernández-Lucio ◽  
Octavio Pereira Neto ◽  
Gaizka Gómez-Escudero ◽  
Francisco Javier Amigo Fuertes ◽  
Asier Fernández Valdivielso ◽  
...  
Keyword(s):  
Cutting Speed ◽  
High Volume ◽  
Cemented Carbide ◽  
Performance Ratio ◽  
Cost Performance ◽  
Ceramic Tools ◽  
The Cost ◽  
Engine Components ◽  
Coated Carbide ◽  
Milling Tools

Productivity in the manufacture of aircrafts components, especially engine components, must increase along with more sustainable conditions. Regarding machining, a solution is proposed to increase the cutting speed, but engines are made with very difficult-to-cut alloys. In this work, a comparison between two cutting tool materials, namely (a) cemented carbide and (b) SiAlON ceramics, for milling rough operations in Inconel® 718 in aged condition was carried out. Furthermore, both the influence of coatings in cemented carbide milling tools and the cutting speed in the ceramic tools were analysed. All tools were tested until the end of their useful life. The cost performance ratio was used to compare the productivity of the tested tools. Despite the results showing higher durability of the coated carbide tool, the ceramic tools presented a better behavior in terms of productivity at higher speed. Therefore, ceramic tools should be used for higher productivity demands, while coated carbide tools for low speed-high volume material removal.

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