A Multidisciplinary Optimization Method for Designing Boundary Layer Ingesting Inlets

2002 ◽  
Author(s):  
David Rodriguez
Keyword(s):  
Boundary Layer ◽  
Optimization Method ◽  
Multidisciplinary Optimization

Secondary Flow Loss Reduction Method by Use of Endwall Contouring in Gas Turbine Cascade Using Optimization Method

2021 ◽  
Author(s):  
Kazuki Yamamoto ◽  
Ryota Uehara ◽  
Shohei Mizuguchi ◽  
Masahiro Miyabe
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Cross Flow ◽  
Internal Flow ◽  
Optimization Method ◽  
Loss Reduction ◽  
Turbine Cascade ◽  
Flow Loss ◽  
Endwall Contouring

Abstract High efficiency is strongly demanded for gas turbines to reduce CO2 emissions. In order to improve the efficiency of gas turbines, the turbine inlet temperature is being raised higher. In that case, the turbine blade loading is higher and secondary flow loss becomes a major source of aerodynamic losses due to the interaction between the horseshoe vortex and the strong endwall cross flow. One of the authors have optimized a boundary layer fence which is a partial vane to prevent cross-flow from pressure-side to suction-side between blade to blade. However, it was also found that installing the fence leads to increase another loss due to tip vortex, wake and viscosity. Therefore, in this paper, we focused on the endwall contouring and the positive effect findings from the boundary layer fence were used to study its optimal shape. Firstly, the relationship between the location of the endwall contouring and the internal flow within the turbine cascade was investigated. Two patterns of contouring were made, one is only convex and another is just concave, and the secondary flow behavior of the turbine cascade was investigated respectively. Secondly, the shape was designed and the loss reduction effect was investigated by using optimization method. The optimized shape was manufactured by 3D-printer and experiment was conducted using cascade wind tunnel. The total pressure distributions were measured and compared with CFD results. Furthermore, flow near the endwall and the internal flow of the turbine cascade was experimentally visualized. The internal flow in the case of a flat wall (without contouring), with a fence, and with optimized endwall contouring were compared by experiment and CFD to extract the each feature.

Optimization Method for Planetary Boundary Layer Height Retrieval by Lidar

2021 ◽  
Vol 41 (7) ◽  
pp. 0728002
Author(s):  
于思琪 Yu Siqi ◽  
刘东 Liu Dong ◽  
徐继伟 Xu Jiwei ◽  
王珍珠 Wang Zhenzhu ◽  
吴德成 Wu Decheng ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Optimization Method ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height

Optimization design of bonnet inner based on pedestrian head protection and stiffness requirements

2017 ◽  
Vol 06 (01) ◽  
pp. 1750005 ◽  
Author(s):  
Xiongqi Peng ◽  
Purit Thanakijkasem ◽  
Xiaomin Zeng ◽  
Hongsheng Lu
Keyword(s):  
Optimization Design ◽  
Parametric Design ◽  
Optimization Method ◽  
Multidisciplinary Optimization ◽  
Fe Model ◽  
Optimization Analysis ◽  
Stiffness Analysis ◽  
Design And Optimization ◽  
Car Accidents ◽  
Head Protection

Head impact with bonnet is one of the major causes for pedestrian severe injury or fatality in car accidents. This paper proposes a multidisciplinary design optimization method for bonnet inner based on pedestrian head protection along with bonnet stiffness requirement. A finite element (FE) model of a child headform impactor is developed and verified via simulation according to Global Technical Regulation No. 9 (GTR No. 9). Static stiffness analysis and headform collision simulation against one impact point for a particular bonnet are implemented. Parametric design and optimization analysis are carried out. Optimization solution significantly achieves a better head protection effect, which clearly affirms the feasibility of the proposed multidisciplinary optimization method and provides a reference approach to optimal design of engine bonnet inner.

scholarly journals Diagnosing Coherent Structures in the Convective Boundary Layer by Optimizing Their Vertical Turbulent Scalar Transfer

2019 ◽  
Vol 174 (1) ◽  
pp. 119-144 ◽  
Author(s):  
Georgios A. Efstathiou ◽  
John Thuburn ◽  
Robert J. Beare
Keyword(s):  
Boundary Layer ◽  
Coherent Structures ◽  
Convective Boundary Layer ◽  
Thermodynamic Characteristics ◽  
Optimization Method ◽  
Area Fraction ◽  
Optimization Approach ◽  
Turbulent Transfer ◽  
Scalar Flux ◽  
Convective Boundary

Abstract A new method is introduced to identify coherent structures in the convective boundary layer, based on optimizing the vertical scalar flux in a two-fluid representation of turbulent motions as simulated by a large-eddy simulation. The new approach partitions the joint frequency distribution (JFD) of the vertical velocity and a transported scalar into coherent structures (fluid 2) and their environment (fluid 1) by maximizing that part of the scalar flux resolved by the mean properties in fluid 2 and fluid 1. The proposed method does not rely on any a priori criteria for the partitioning of the flow nor any pre-assumptions about the shape of the JFD. Different flavours of the optimization approach are examined based on maximizing either the total (fluid 1 $$+$$+ fluid 2) or the fluid-2 resolved scalar flux, and on whether all possible partitions or only a subset are considered. These options can result in different derived area fractions for the coherent structures. The properties of coherent structures diagnosed by the optimization method are compared to the conditional sampling of a surface-emitted decaying tracer, in which coherent structures are defined as having tracer perturbation greater than some height-dependent threshold. Results show that the optimization method is able to smoothly define coherent thermal structures in both the horizontal and the vertical. Moreover, optimizing the turbulent transfer by the fluid-2 resolved flux produces very similar coherent structures to the tracer threshold method, especially in terms of their area fraction and updraft velocities. Nonetheless, further analysis of the partitioning of the JFD reveals that, even though the area fraction of coherent structures might be similar, their definition can occupy different quadrants of the JFD, implying the contribution of different physical mechanisms to the turbulent transfer in the boundary layer. Finally, the kinematic and thermodynamic characteristics of the coherent structures are examined based on their definition criteria.

Design of a Human-Powered Aircraft Applying Multidisciplinary Optimization Method

2013 ◽  
Author(s):  
Gustavo Fujiwara ◽  
Luciano Martinez Stefanini ◽  
Otavio Silvares
Keyword(s):  
Optimization Method ◽  
Multidisciplinary Optimization ◽  
Human Powered

scholarly journals Effect of Air-Ducted Blade Design on Horizontal Axis Wind Turbine Performance

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3618
Author(s):  
Cemil Yigit
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Boundary Layer Separation ◽  
Optimization Method ◽  
Power Coefficient ◽  
Critical Number ◽  
Horizontal Axis Wind Turbine ◽  
Local Boundary ◽  
Response Surface Optimization ◽  
Computational Fluid Dynamics Analysis

Wind turbines without pitch control are more preferable from economical point of view but aerodynamic stall affects them more and after a critical wind speed local boundary layer separation occurs. Consequently, their power production is relatively low. In this study, air ducts added on the blade and using the airflow from them the kinetic energy of the low-momentum fluid behind the surface was increased and delay of separation of the boundary layer from the surface was examined The Response Surface Optimization method was utilized in order to get the best possible design under the constraints and targets arranged for the parameters termed the diameter, slope, number and angle of attack of the air ducts. By using computational fluid dynamics analysis, optimum parameter values were obtained and air-ducted and air-duct free blade designs were compared. An improvement in power coefficient between 3.4–4.4% depending on wind speed was achieved with the new design. Due to increase in viscous forces, more power from the rotor obtained by opening air ducts up to a critical number. However, the results showed that after the critical number of air duct addition of more duct on the blade reduced the power coefficient.

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