Advances in Aerodynamic Drag Extraction by Far-Field Methods

Lanzetta, Marco; Mele, Benedetto; Tognaccini, Renato

doi:10.2514/1.c033095

Cited by 28 publications

(4 citation statements)

References 24 publications

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“…It is clear that the breakdown method relies on a proper selection of the three domains Ω visc , Ω sw and Ω sp . This is performed by the definition of boundary layer and shockwave sensors discussed in [24,25]. Recently, Saetta and Tognaccini proposed a region identification based on a machine-learning algorithm independent of numerical input or thresholds [26].…”

Section: Far-field Force Methodsmentioning

confidence: 99%

Drag Reduction by Wingtip-Mounted Propellers in Distributed Propulsion Configurations

Minervino

Andreutti

Russo

et al. 2022

Fluids

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Tip-mounted propellers can increase wing aerodynamic efficiency, and the concept is gaining appeal in the context of hybrid electrical propulsion for greener aviation, as smaller and lighter electrical motors can help with mitigating structural drawbacks of a tip engine installation. A numerical study of tip propeller effects on wing aerodynamics is herein illustrated, considering different power configurations of a Regional Aircraft wing. A drag breakdown analysis using far-field methods is presented for one of the most promising configurations, and a comparison between drag reductions obtained with a tip propeller or a standard winglet installation is also provided. Numerical flow simulations using Finite Volume Methods with actuator disk models are compared with results of a Vortex-Lattice Method, and far-field aerodynamic force calculation is performed for different mesh sizes. A wing drag reduction up to 6% (10%) is predicted under typical cruise (climb) flight conditions when wingtip-mounted propellers take over half of the total thrust usually provided by turbo-prop engines installed at inboard wing position. Drag breakdown analysis confirmed that the observed benefits mainly come from a reduction in the reversible drag component, increasing the effective wing span efficiency.

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Section: Far-field Force Methodsmentioning

confidence: 99%

Drag Reduction by Wingtip-Mounted Propellers in Distributed Propulsion Configurations

Minervino

Andreutti

Russo

et al. 2022

Fluids

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“…The main reason is that there are large differences in eddy viscosity among different RANS flow solvers, though their mean flow solutions are very similar. Using other turbulence model related quantities 15 as the viscous sensor function may encounter the same issue. Unlike the classical method, the vorticity based function uses vorticity and strain, which depend on mean flow velocity gradients and are independent of turbulence models.…”

Section: Area Selection Strategymentioning

confidence: 99%

“…Gariepy et al 11 and Meheut et al 8 separately proposed a new AVD formula to fix the discontinuity issue of the Destarac formula when the total pressure is lower than the undisturbed static pressure, which causes the negative quantity under square root operator. Lanzetta et al 15 compared several viscous area sensor functions and concluded that the dissipation of turbulence kinetic energy is the most effective sensor function. However, this parameter is only available in the two-equation turbulence models.…”

Section: Introductionmentioning

confidence: 99%

Far-field drag decomposition using hybrid formulas and vorticity based area sensors

Qiao

Sun

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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Numerical simulation of flow-field has become an indispensable tool for aerodynamic design. Usually, wall surface integration is a tool used to calculate values of pressure drag and skin friction drag, but the aerodynamic mechanism of drag production is still confusing. In present work, in order to decompose the total drag into viscous drag, wave drag, induced drag, and spurious drag, a far-field drag decomposition (FDD) method is developed. This method depends on axial velocity defect and area sensor functions. The present work proposes three hybrid formulas for velocity defect to tackle the negative square root issue by analyzing the existing axial velocity defect formulas. For dealing with the issue of detection failure for near-wall cells, a novel vorticity based viscous area sensor function is proposed. The new area sensor function is also independent of the turbulence model, which ensures easy application to general simulation methods for flow-field. Three tests cases are there to validate the proposed FDD method. The three dimensional transonic CRM test case shows that the present improvement is crucial for accurate drag decomposition. Excellent agreement between total decomposed drags and results from the near-field method or experimental data further confirms the correctness.

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“…With this choice, the model could evaluate, as a result of the numerical simulation, the optimal riblet height distribution over the aircraft surface (Figure 14). A drag breakdown by far-field methods [43,44] allowed the analysis of the effects of the riblets on the form drag and on the shock wave. In Figures 15 and 16, the viscous drag breakdown showed that the reduction in form drag contributed to the total drag reduction, and that the decrease in the total drag reduction with the angle of attack was certainly due to the increase in induced drag on which the riblets did not act but also to the decrease in form drag reduction.…”

Section: Modeling the Riblet Effect On Aircraft Configurationmentioning

confidence: 99%

Riblet Drag Reduction Modeling and Simulation

Mele

2022

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One of the most interesting passive drag reduction techniques is based on the use of riblets or streamwise grooved surfaces. Detailed flow features inside the grooves can be numerically detected only by Direct Numerical Simulations (DNS), still unfeasible for high Reynolds numbers and complex flows. Many papers report the DNS of flows on microgrooved surfaces providing fundamental details on the drag reduction devices, but all are limited to plate or channel flows far from engineering Reynolds numbers. The numerical simulation of riblets and other drag reduction devices at very high Reynolds numbers is difficult to perform due to the riblet dimensions (microns in aeronautical applications). To overcome these difficulties, some models for riblet simulation have been developed in recent years, due to the data provided by DNS, experiments, and theoretical analyses. In all these models, the drag reduction is modeled rather than effectively captured; however, the analysis of some nonlocal effects on practical aeronautical configurations with riblets, requires their adoption. In this paper, the capabilities of these models in predicting riblets’ performance and some interesting features of the riblets’ effect on form drag and shock waves are shown. Two models are discussed and compared showing their respective advantages and limitations and providing possible enhancements. A comparison between the two models in terms of accuracy and convergence is discussed, and two new formulae are proposed to improve one of these models. Finally, a review of the results obtained by the two models is provided showing their capabilities in the analysis of the riblet effect on complex configurations.

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Advances in Aerodynamic Drag Extraction by Far-Field Methods

Cited by 28 publications

References 24 publications

Drag Reduction by Wingtip-Mounted Propellers in Distributed Propulsion Configurations

Drag Reduction by Wingtip-Mounted Propellers in Distributed Propulsion Configurations

Far-field drag decomposition using hybrid formulas and vorticity based area sensors

Riblet Drag Reduction Modeling and Simulation

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