A Turbofan-Engine Nacelle Shape Design and Optimization Method for Natural Laminar Flow Control

2016 ◽  
Author(s):  
Songyang Li ◽  
Yongjian Zhong
Keyword(s):  
Laminar Flow ◽  
Drag Coefficient ◽  
Longitudinal Profile ◽  
Shape Design ◽  
Aerodynamic Shape ◽  
Optimization System ◽  
Transition Prediction ◽  
Profile Line ◽  
Natural Laminar Flow ◽  
Engine Nacelle

A correctly profiled engine nacelle can delay the transition in the boundary layer and allow laminar flow to extend back, resulting in a substantial drag reduction. Therefore, the laminar flow nacelle has lower fuel consumption than current turbulent designs. In this paper, aerodynamic shape optimization of natural laminar flow nacelle has been studied by using a novel nacelle shape design method and transition prediction with CFD. First, the 2D longitudinal profile-line of nacelle is optimized, in order to extend its laminar region and achieve minimum drag coefficient within the design space. Second, the optimized longitudinal profile-line is then circumferentially stacked to construct the 3D nacelle aerodynamic shape. At last, the aerodynamic improvement of the new shape is evaluated by 3D CFD simulation. A nacelle geometry generator has been developed where the deflection angle (related to the curvature) along the cord is controlled by using Non-Uniform Rational B-Splines. It is then analytically integrated to obtain the longitudinal profile-line. And also a leading edge matching function is involved in the generator. This technique improves the smoothness of nacelle profile-line, which ensures the curvature and slope of curvature to be continuous all over the nacelle surface. The pressure distribution over the nacelle surface has been improved with no spikes in Mach number. A transition model coupling with shear stress transport turbulent model is used in solving Navier-Stokes equations for transition prediction. An optimization system has been established in combination with the geometry generator, the transition prediction model with CFD, a Kriging surrogate model and a Multi-Island Genetic Algorithm. As a result, the aerodynamic improvement, with one profile-line optimized, is obvious against the original nacelle shape by CFD validation in 3D simulation. The optimized nacelle can achieve a laminar flow up to 23% and its drag coefficient has reduced by 6.5%. It is indicated that the optimization system is applicable in nacelle aerodynamic shape design.

A 3D Shape Design and Optimization Method for Natural Laminar Flow Nacelle

2017 ◽  
Author(s):  
Yongjian Zhong ◽  
Songyang Li
Keyword(s):  
Boundary Layer ◽  
Simulated Annealing ◽  
Laminar Flow ◽  
Drag Coefficient ◽  
Frictional Drag ◽  
Initial Shape ◽  
Aerodynamic Shape ◽  
Profile Line ◽  
Adaptive Simulated Annealing ◽  
Natural Laminar Flow

With the rapid development of high bypass ratio turbofan engine, the proportion of the nacelle drag increases obviously in the total drag of the aircraft with the increase of nacelle surface area. And the frictional resistance is one of the major contributors of drag. Under the same Reynolds number, the friction resistance in turbulent boundary layer is about 10 times larger as that in laminar boundary layer. Therefore, a correctly profiled engine nacelle will delay the transition in the boundary layer and allow laminar flow to extend back, resulting in a substantial drag reduction. In the previous conference paper (9th reference), a 2D nacelle longitudinal profile-line geometry generator, which allows curvature and slope-of-curvature to be continuous was developed and presented. This established an optimization system to minimize nacelle frictional drag. One of the nacelle profile-line is optimized to achieve minimum drag coefficient, and then is stacked with the other original profile-lines to form the 3D isolated nacelle aerodynamic shape. Finally, a total 23% of nacelle outer surface maintains a laminar flow and its frictional drag coefficient is less than initial shape. This paper proposes a new 2D nacelle longitudinal profile-line design method, based on PARSEC parameterization, with can generate the profile-line rapidly and precisely. Conservation Full Potential Equation was used to calculate the aerodynamic distribution and obtain the transition location. Then adaptive simulated annealing genetic algorithm was adapted to search 2D profiles of low drag, which would be applied to narrow down design space in 3D nacelle optimization. Second, 2D profiles were stacked circumferentially, by NURBS surface generator, to form the 3D nacelle aerodynamic shape, and an optimization system was established, in combination with the 3D nacelle generator, γ–Reθ transition model, Kriging surrogate model and adaptive simulated annealing algorithm, for natural laminar flow nacelle design. Finally, a total 34% of nacelle surface maintains a laminar flow and its frictional drag coefficient is less than initial shape. The generated optimized loft was evaluated by CFD to determine if the low drag of this optimized nacelle shape can be maintained under different Mach numbers and angles of attack.

scholarly journals Aerodynamic Shape Design and Validation of an Advanced High-Lift Device for a Regional Aircraft with Morphing Droop Nose

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Alessandro De Gaspari ◽  
Frédéric Moens
Keyword(s):  
Laminar Flow ◽  
Tracking System ◽  
Three Dimensional ◽  
Design Procedure ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Shape Design ◽  
High Lift ◽  
Aerodynamic Shape ◽  
Natural Laminar Flow

In the present work, the aerodynamic shape design of an advanced high-lift system for a natural laminar flow (NLF) wing, based on the combination of a morphing droop nose and a single slot trailing edge flap, is presented. The paper presents both the aerodynamic design and optimization of the NLF wing and the high-lift configuration considering the mutual effects of both flap devices. Concerning the morphing droop nose (DN), after defining the parameterization techniques adopted to describe the geometry in terms of morphing shape and flap settings, the external configuration is obtained by an aerodynamic shape optimization procedure able to meet geometrical constraints and the skin structural requirements due to the morphing. The final performance assessment of the three-dimensional high-lift configurations is performed by high-fidelity aerodynamic analyses. The design procedure is applied to a twin-prop regional aircraft equipped with a natural laminar flow wing. The morphing droop nose is compatible with an NLF wing that requires the continuity of the skin and, at the same time, extends the possibilities to improve the performances of the class of regional aircraft which usually are not equipped with conventional leading edge devices. Additionally, the morphing technology applied to the flap allows the design of a tracking system fully integrated inside the airfoil geometry, leading to a solution without external fairings and so with no extra friction drag penalty for the aircraft.

Aerodynamic Shape Optimization of Natural-Laminar-Flow Wing Using Surrogate-Based Approach

AIAA Journal ◽  
2018 ◽  
Vol 56 (7) ◽  
pp. 2579-2593 ◽  
Author(s):  
Zhong-Hua Han ◽  
Jing Chen ◽  
Ke-Shi Zhang ◽  
Zhen-Ming Xu ◽  
Zhen Zhu ◽  
...  
Keyword(s):  
Laminar Flow ◽  
Shape Optimization ◽  
Aerodynamic Shape Optimization ◽  
Aerodynamic Shape ◽  
Natural Laminar Flow

Natural laminar flow airfoil shape design at transonic regimes with multi-objective evolutionary algorithms

2017 ◽  
Vol 233 (3) ◽  
pp. 991-999 ◽  
Author(s):  
Yongbin Chen ◽  
Zhili Tang
Keyword(s):  
Shock Wave ◽  
Laminar Flow ◽  
Evolutionary Algorithms ◽  
Flow Region ◽  
Wave Drag ◽  
Linear Stability Theory ◽  
Shape Design ◽  
Multi Objective ◽  
Natural Laminar Flow ◽  
Wave Control

The natural laminar flow airfoil shape design at transonic regime is solved using multi-objective evolutionary algorithms in this paper. A shock wave control bump is used to reduce wave drag of natural laminar flow airfoil in transonic flow, and the eN transition prediction method based on the linear stability theory is used to predict the transition location. The multi-island parallel multi-objective evolutionary algorithms is implemented to optimize the airfoil shape equipped with shock wave control bump for obtaining a larger laminar flow region and a weaker wave drag simultaneously. Optimization experiment shows that it is easy to capture the Pareto front of wave drag minimization and laminar flow region maximization. Results demonstrate that both wave drag and friction drag performance of several chosen Pareto members are significantly improved via the optimal airfoil shape and shock wave control bump device compared to that of the baseline shape.

Natural laminar flow flight experiments on a turbine engine nacelle fairing

1986 ◽  
Author(s):  
C. OBARA ◽  
E. HASTINGS ◽  
J. SCHOENSTER ◽  
T. PARROTT ◽  
B. HOLMES
Keyword(s):  
Laminar Flow ◽  
Turbine Engine ◽  
Natural Laminar Flow ◽  
Engine Nacelle
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