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.

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.

scholarly journals Body-force modeling for aerodynamic analysis of air intake – fan interactions

2016 ◽  
Vol 26 (7) ◽  
pp. 2048-2065 ◽  
Author(s):  
William Thollet ◽  
Guillaume Dufour ◽  
Xavier Carbonneau ◽  
Florian Blanc
Keyword(s):  
Body Force ◽  
Stokes Equations ◽  
The Body ◽  
Test Case ◽  
Force Model ◽  
Strong Impact ◽  
Analytic Model ◽  
Source Terms ◽  
Content Type ◽  
Air Intake

Purpose The purpose of this paper is to explore a methodology that allows to represent turbomachinery rotating parts by replacing the blades with a body force field. The objective is to capture interactions between a fan and an air intake at reduced cost, as compared to full annulus unsteady computations. Design/methodology/approach The blade effects on the flow are taken into account by adding source terms to the Navier-Stokes equations. These source terms give the proper amount of flow turning, entropy, and blockage to the flow. Two different approaches are compared: the source terms can be computed using an analytic model, or they can directly be extracted from RANS computations with the blade’s geometry. Findings The methodology is first applied to an isolated rotor test case, which allows to show that blockage effects have a strong impact on the performance of the rotor. It is also found that the analytic body force model underestimates the mass flow in the blade row for choked conditions. Finally, the body force approach is used to capture the coupling between a fan and an air intake at high angle of attacks. A comparison with full annulus unsteady computations shows that the model adequately captures the potential effects of the fan on the air intake. Originality/value To the authors’ knowledge, it is the first time that the analytic model used in this paper is combined with the blockage source terms. Furthermore, the capability of the model to deal with flows in choked conditions was never assessed.

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.

Development of body force model for steady inlet distortions in high-speed multistage compressor

2016 ◽  
Vol 231 (9) ◽  
pp. 1650-1659 ◽  
Author(s):  
Jin Guo ◽  
Jun Hu
Keyword(s):  
Performance Analysis ◽  
Body Force ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
The Body ◽  
Force Model ◽  
Source Terms ◽  
Analysis Model ◽  
Multistage Compressor ◽  
The Impact

This study aims at establishing a three-dimensional numerical model, compressor aerodynamic performance analysis model, to simulate the impact of complicated distorted flow on multistage axial flow compressor based on the body force model. The model solves the compressible three-dimensional Euler equations, which are modified to include source terms representing the effect of the blade rows. In this study, the association between blade source terms and entry Mach number together with attack angle could be established with the deviation angle model and loss model. In this paper, compressor aerodynamic performance analysis model is used to evaluate the effect of inlet circumferential total pressure distortion and swirl distortion on a five-stage high-pressure compressor. Calculated operating maps for compressor agree well with the experimental results. Meanwhile, the traveling process of inlet distortions in the multistage compressor is correctly revealed. The wide application prospect of the model can be seen in the area of inlet distortion problems.

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 Computational Modeling of Vortex Generators for Turbomachinery

2002 ◽  
Author(s):  
R. V. Chima
Keyword(s):  
Computational Models ◽  
Body Force ◽  
Secondary Flows ◽  
The Body ◽  
Vortex Generators ◽  
Force Model ◽  
Suction Surface ◽  
Near Surface ◽  
Compressor Rotor ◽  
Surface Particle

In this work computational models were developed and used to investigate applications of vortex generators (VGs) to turbomachinery. The work was aimed at increasing the efficiency of compressor components designed for the NASA Ultra Efficient Engine Technology (UEET) program. Initial calculations were used to investigate the physical behavior of VGs. A parametric study of the effects of VG height was done using 3-D calculations of isolated VGs. A body force model was developed to simulate the effects of VGs without requiring complicated grids. The model was calibrated using 2-D calculations of the VG vanes and was validated using the 3-D results. Then three applications of VGs to a compressor rotor and stator were investigated: 1. The results of the 3-D calculations were used to simulate the use of small casing VGs used to generate rotor preswirl or counterswirl. Computed performance maps were used to evaluate the effects of VGs. 2. The body force model was used to simulate large partspan splitters on the casing ahead of the stator. Computed loss buckets showed the effects of the VGs. 3. The body force model was also used to investigate the use of tiny VGs on the stator suction surface for controlling secondary flows. Near-surface particle traces and exit loss profiles were used to evaluate the effects of the VGs.

Stresses and Displacements in a Rotating Conical Shell

1943 ◽  
Vol 10 (2) ◽  
pp. A53-A61
Author(s):  
J. L. Meriam
Keyword(s):  
Conical Shell ◽  
Body Force ◽  
Theory Of Elasticity ◽  
Common Type ◽  
The Body ◽  
Surface Loading ◽  
Thin Walled Structures ◽  
Special Cases ◽  
Engineering Problems ◽  
Rotating Conical Shell

Abstract The analysis of shells is an important subdivision of the general theory of elasticity, and its application is useful in the solution of engineering problems involving thin-walled structures. A common type of shell is one which possesses symmetry with respect to an axis of revolution. A theory for such shells has been developed by various investigators (1, 2, 3, 6) and applied to a few simple cases such as the cylindrical, spherical, and conical shapes. Boundary conditions, for the most part, have been simple static ones, and conditions of surface loading have been included in certain special cases. This paper extends the theory of axially symmetrical shells by including the body force of rotation about the axis and applies the results to the rotating conical shell. The analysis follows a pattern established by several investigators (1, 2, 3, 6) and for this reason is abbreviated to a considerable extent. Only where the inclusion of the body force makes elucidation advisable or where a slightly different method of approach is used are the steps presented in more detail.

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