Eric Laurendeau

Nonlinear Generalized Lifting-Line Coupling Algorithms for Pre/Poststall Flows

Numerical algorithms and solutions of generalized nonlinear lifting-line theory over an elliptical wing are examined, with emphasis on near/poststall flows. First, a thorough analysis on the circulation-based and angle-of-attack-based correction methods (Γ and α methods, respectively) highlights their respective numerical poststall characteristics. The stability of the method is demonstrated, producing single and multiple solutions in the pre- and poststall regions, respectively. Second, artificial dissipation added to the α method is shown to be an effective means of controlling the poststall flow region. Finally, a strongly coupled algorithm is presented, allowing to bypass the interpolation phase via the use of Legendre polynomials. The model sheds light on poststall flow behavior, in agreement with several papers studying formation of stall cell patterns.

Far-Field Drag Decomposition Applied to the Drag Prediction Workshop 5 Cases

A far-field drag prediction and decomposition method has been applied to the results of the AIAA Drag Prediction Workshop 5 held in Louisiana during the summer of 2012. The method has two principal advantages: it allows the removal of spurious drag inherent to computational fluid dynamics solutions, and it allows the decomposition of drag into viscous, wave, and induced physical drag components. This research shows that accurate drag coefficients can be predicted on coarse grids when the spurious drag is extracted with the far-field method and that these results are closer to experimental values than drag coefficients computed on finer meshes when spurious drag is not extracted. The research also investigated the reasons behind the lift and drag losses found by some participants in the workshop. It is shown that the lift loss is caused by the boundary-layer separation at the wing root, inducing a reduction of 20% of the shock wave drag and a significant change in the wing loading. The initiation of buffet...

Quasi-Steady Convergence of Multistep Navier–Stokes Icing Simulations

A newly developed two-dimensional ice accretion and antiicing simulation code, CANICE2D-NS, is presented. The method is used to predict iced airfoil shapes and performance degradation with a multistep approach. A multiblock Navier–Stokes code, NSMB, has been coupled with the CANICE2D icing framework, supplementing the existing panel method-based flow solver. Attention is paid to the roughness implementation within the turbulence model and to the convergence of the steady and quasi-steady iterative procedure. The new coupling allows fully automated multilayer icing simulation, whereas also permitting flow analysis and performance prediction of iced airfoils. Effects of uniform surface roughness in quasi-steady ice accretion simulation are analyzed through different validation test cases. The results demonstrates the benefits and robustness of the new framework in predicting ice shapes and aerodynamic performance parameters, as well as iced airfoil surface pressure coefficients. Finally, the convergence of ...

Grid-Generation Algorithms for Complex Glaze-Ice Shapes Reynolds-Averaged Navier–Stokes Simulations

The paper presents the developments of novel mesh generation algorithms over complex glaze-ice shapes containing multicurvature ice-accretion geometries, such as single/double ice horns. The twofold approaches tackle surface geometry discretization as well as field mesh generation. First, an adaptive curvilinear curvature control algorithm is constructed, solving a one-dimensional elliptic partial differential equation with periodic source terms. This method controls the arc length grid spacing, so that high convex and concave curvature regions around ice horns are appropriately captured, and is shown to effectively treat the grid shock problem. Second, a novel blended method is developed by defining combinations of source terms with two-dimensional elliptic equations. The source terms include two common control functions, Sorenson and Spekreijse, and an additional third source term to improve orthogonality. This blended method is shown to be very effective for improving grid quality metrics for complex g...

Preliminary-Design Aerodynamic Model for Complex Configurations Using Lifting-Line Coupling Algorithm

A modern nonlinear-lifting-line-theory algorithm allowing the prediction of aerodynamic coefficients and lifting-surface-pressure distribution for multiple aircraft configurations is presented. The algorithm is applied to isolated wing, high-lift systems (slat/main/flap), and multisurface configurations, with emphasis on the treatment of high-lift geometry representations. The fuselage is not geometrically modeled, but its influence is appropriately taken into account for the aerodynamic-coefficient evaluation. The results show good agreements with wind-tunnel and/or high-fidelity numerical data for the prediction of the maximum lift coefficient and the poststall behavior in subsonic and transonic conditions. The use of sectional airfoil data obtained via solutions of the Reynolds-averaged Navier–Stokes equations with infinite-swept-wing assumptions—so-called 2.5-dimensional model—is shown to greatly improve the results over traditional two-dimensional solutions.

Validation and Verification of Multi-Steps Icing Calculation Using CANICE2D-NS Code

A newly developed Navier-Stokes based two-dimensional ice accretion and anti-icing simulation code, CANICE2D-NS is presented. The method is devised to be fully automated for use within a multi-step approach capable of analyzing long ice accretion accumulation times in a quasi-steady formulation. An efficient single-block structured Navier-Stokes CFD code, NSCODE, have been coupled with the CANICE2D icing framework, supplementing the existing panel method based flow solver. Attention is paid to the roughness implementation within the turbulence model, and to acceleration of the convergence of the steady and quasi-steady iterative procedures. Effects of uniform surface roughness in quasi-steady ice accretion simulation are analyzed through different validation test cases, including code to code comparisons with the same framework coupled with another Navier-Stokes solver. The efficiency of the J-multigrid approach to solve the flow equations on complex iced geometries is demonstrated. Finally, results on up to 160 quasi time-steps calculations are presented and analyzed. 1 Ph.D. student, kazem.hasanzadeh@polymtl.ca. 2 Postdoctoral student, ali.mosahebi@gmail.com. 3 Assistant Professor, eric.laurendeau@polymtl.ca. 4 Professor, ion.paraschivoiu@polymtl.ca.

Far-Field Drag Decomposition Method Applied to the DPW-5 Test Case Results

A fareld drag prediction and decomposition method has been applied to the results of AIAA Drag Prediction Workshop 5 (DPW-5) held in Louisiana during the summer of 2012. The method has two principal advantages: it allows the removal of spurious drag inherent to CFD solutions, and it allows the decomposition of drag into viscous, wave, and induced physical drag components. This research shows that accurate drag coe cients can be predicted on coarse grids when the spurious drag is extracted with the fareld method, and that these results are closer to experimental values than drag coe cients computed on ner meshes when spurious drag is not extracted. The research also investigated the reasons behind the lift and drag losses found by some participants in the Workshop. It is shown that the lift loss is caused by the boundary layer separation at the wing root, inducing a reduction of 20% of the shock wave drag and a signi cant change in wing loading. The initiation of bu et is also analyzed. The study shows that mesh re nement is critical to capture the physical e ects of the ow, such as its separation, and provides an explanation of the discrepancies in results observed at DPW-5.

Recent Developments of the Navier Stokes Multi Block (NSMB) CFD solver.

The Navier Stokes Multi Block solver NSMB was initially developed in 1992 at the Swiss Federal Institute of Technology (EPFL) in Lausanne, and from 1993 onwards in the NSMB consortium composed of different universities, research establishments and industries. Today NSMB is developed by IMF-Toulouse (IMFT), ICUBE (Strasbourg), University of Munchen (TUM, Germany), University of the Army in Munchen, Ecole Polytechnique Montreal, Airbus Defence and Space, RUAG Aviation and CFS Engineering. At the Aerospace Sciences Meeting in 1998 an overview of the developments of NSMB was given . Since then various papers have been published on NSMB, examples are . This paper will present several recent developments of NSMB and the use of NSMB for industrial test cases.

NSMB contribution to the 2nd High Lift Prediction Workshop

A numerical analysis of the flow on the DLR-F11 high lift model in landing configuration is presented within the context of the 2 High Lift Prediction Workshop. The objective is to describe the flow state and characterize the numerical parameters influencing the solution. The NSMB flow solver is used for this purpose, both in steady and unsteady Reynolds-Averaged Navier-Stokes modes. The geometry used is the simplified model (without bracket and bundle). In addition to a grid convergence study, efforts concentrated on the effect of grid size, turbulence model, initialization scheme in the steady flow regime, and to unsteady flow effects. In particular, additional data points to the ones required for the workshop were added in the stall region to further the understanding of the physical phenomena in play. The results show that loss of lift can occur via separate phenomena, one at the wing root, and the other at the wing tip. It also highlights the necessity of performing unsteady flow simulations, since steady flow cannot be achieved for this class of flow problems.

Development of a three-dimensional icing simulation code in the NSMB flow solver

An icing model is developed in the Navier-Stokes multi-block (NSMB) compressible solver. The code implemented in this study is based on an Eulerian formulation for droplets tracking solved implicitly by means of CGSTAB or SIP methods, a modified iterative Messinger model using an improved water runback scheme for ice thickness calculation and three-dimensional mesh deformation to track the ice/air interface through time. The whole process is parallelised with MPI for efficient calculations. Validation is performed on several test cases including NACA23012 and NACA00012 airfoils and ONERA-M6 swept wing. Pressure coefficients around iced 23012 airfoil are compared with experimental data. Rime icing is computed on a DLR-F6 wing/body configuration. In all studied cases, the results are in good agreement with the literature.