Modifications of class-shape transformation driven by aerodynamic concerns over leading-edge region

2021 ◽  
pp. 095441002098457
Author(s):  
Shuyue Wang ◽  
Cong Wang ◽  
Gang Sun
Keyword(s):  
Design Space ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Shape Error ◽  
Edge Region ◽  
Aerodynamic Design ◽  
Shape Transformation ◽  
Geometrical Representation ◽  
Design Variables ◽  
Representation Method

Geometrical representation method plays a fundamental role in aerodynamic design in that it makes preparation for design space. A good design space should be composed of design variables that are more likely to attain the solution to the problem than others. This study finds that due to the characteristics of Bernstein polynomials, a conventional class-shape transformation (CST) geometrical representation method is insufficiently focused on the leading-edge region of airfoils/wings. However, more aerodynamic attention is required there because it has strong relationship with the aerodynamic performance of whole geometry. The lack of design variables assigned to the leading-edge region is likely to compromise the effort in finding better optimization results in design space. While maintaining the convenience and accuracy of conventional CST, this study proposes two types of modifications to add more aerodynamic insights into the leading-edge region: (1) an approach of supplementary vertical CST aiming to describe the leading-edge region upon the fitting result of conventional CST; (2) an approach of globally transforming airfoil surfaces into a single-value function with respect to x-direction so that the leading-edge region avoids being split up into two separate parts. With those two modifications, the leading edge can be put to the center of geometric description by rotating the local coordinate system after tackling some other issues that come with the operation. Modification 1 is intuitive, although it requires additional attention to some parameters for the continuity between the leading-edge region and other regions of the airfoil. Modification 2 is convenient to implement, but has limitations on accuracy control because the result of shape error has to account for the introduction global transforming function. Two modifications are illustrated, and their applications are discussed in the study, showing the perspective of being utilized in aerodynamic design that involves delicate difference of aerodynamic performance brought by variations of leading-edge shape.

scholarly journals Aerodynamic Design of Separate-Jet Exhausts for Future Civil Aero-engines—Part I: Parametric Geometry Definition and Computational Fluid Dynamics Approach

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Ioannis Goulos ◽  
Tomasz Stankowski ◽  
John Otter ◽  
David MacManus ◽  
Nicholas Grech ◽  
...  
Keyword(s):  
Design Space Exploration ◽  
Design Space ◽  
Design Parameters ◽  
Small Scale ◽  
Aerodynamic Design ◽  
Shape Transformation ◽  
Design Variables ◽  
Aero Engines ◽  
Engine Cycle ◽  
Exhaust Systems

This paper presents the development of an integrated approach which targets the aerodynamic design of separate-jet exhaust systems for future gas-turbine aero-engines. The proposed framework comprises a series of fundamental modeling theories which are applicable to engine performance simulation, parametric geometry definition, viscous/compressible flow solution, and design space exploration (DSE). A mathematical method has been developed based on class-shape transformation (CST) functions for the geometric design of axisymmetric engines with separate-jet exhausts. Design is carried out based on a set of standard nozzle design parameters along with the flow capacities established from zero-dimensional (0D) cycle analysis. The developed approach has been coupled with an automatic mesh generation and a Reynolds averaged Navier–Stokes (RANS) flow-field solution method, thus forming a complete aerodynamic design tool for separate-jet exhaust systems. The employed aerodynamic method has initially been validated against experimental measurements conducted on a small-scale turbine powered simulator (TPS) nacelle. The developed tool has been subsequently coupled with a comprehensive DSE method based on Latin-hypercube sampling. The overall framework has been deployed to investigate the design space of two civil aero-engines with separate-jet exhausts, representative of current and future architectures, respectively. The inter-relationship between the exhaust systems' thrust and discharge coefficients has been thoroughly quantified. The dominant design variables that affect the aerodynamic performance of both investigated exhaust systems have been determined. A comparative evaluation has been carried out between the optimum exhaust design subdomains established for each engine. The proposed method enables the aerodynamic design of separate-jet exhaust systems for a designated engine cycle, using only a limited set of intuitive design variables. Furthermore, it enables the quantification and correlation of the aerodynamic behavior of separate-jet exhaust systems for designated civil aero-engine architectures. Therefore, it constitutes an enabling technology toward the identification of the fundamental aerodynamic mechanisms that govern the exhaust system performance for a user-specified engine cycle.

Parametric Modeling and Simulation for Aerodynamic Design of Launch Vehicle

2011 ◽  
Vol 101-102 ◽  
pp. 697-701
Author(s):  
Zhong Quan Guo ◽  
Jian Xia Liu ◽  
Wen Cai Luo
Keyword(s):  
Modeling And Simulation ◽  
Modular Design ◽  
Simulation Method ◽  
Launch Vehicle ◽  
Aerodynamic Performance ◽  
Parametric Modeling ◽  
Design Parameters ◽  
Aerodynamic Design ◽  
Geometry Model ◽  
Design Variables

Aerodynamic design of launch vehicle is facing combinatorial explosion problem caused by modular design. In order to get basic feasible solution from huge design space, the efficiency of design and simulation must be improved. In this paper, a parametric modeling and simulation method is proposed, which is based on CAD/CFD tools. Firstly, the design Variables of the launch vehicle are divided into three categories: size parameters, configuration parameters and mesh parameters. Secondly, parametric geometry model, including size and configuration parameters, is obtained by secondary development of Pro/ENGINEER. Thirdly, parametric mesh files for CFD are generated by implementing CFD-GEOM with scripts written in Python. By specifying boundary conditions through command stream of GAMBIT, FLUENT software will run automatically to calculate the aerodynamic performance of the launch vehicle. Finally, a graphical user interface (GUI) is developed using VC++6.0. With this system, the integration of CAD/CFD application is achieved. As long as designers enter certain design parameters in the GUI, they will quickly achieve 3D geometry model and aerodynamic performance of the launch vehicle. Application examples show that, this system can significantly improve the efficiency of aerodynamic design of the launch vehicle, and the data error between simulation and experiment is less than 10%, which is acceptable.

Aerodynamic Design of Separate-Jet Exhausts for Future Civil Aero-engines—Part II: Design Space Exploration, Surrogate Modeling, and Optimization

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Ioannis Goulos ◽  
John Otter ◽  
Tomasz Stankowski ◽  
David MacManus ◽  
Nicholas Grech ◽  
...  
Keyword(s):  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Exhaust System ◽  
Aerodynamic Performance ◽  
Design Tool ◽  
Civil Aviation ◽  
Aerodynamic Design ◽  
Aero Engines ◽  
Exhaust Systems

The aerodynamic performance of the bypass exhaust system is key to the success of future civil turbofan engines. This is due to current design trends in civil aviation dictating continuous improvement in propulsive efficiency by reducing specific thrust and increasing bypass ratio (BPR). This paper aims to develop an integrated framework targeting the automatic design optimization of separate-jet exhaust systems for future aero-engine architectures. The core method of the proposed approach is based on a standalone exhaust design tool comprising modules for cycle analysis, geometry parameterization, mesh generation, and Reynolds-averaged Navier–Stokes (RANS) flow solution. A comprehensive optimization strategy has been structured comprising design space exploration (DSE), response surface modeling (RSM) algorithms, as well as state-of-the-art global/genetic optimization methods. The overall framework has been deployed to optimize the aerodynamic design of two civil aero-engines with separate-jet exhausts, representative of current and future engine architectures, respectively. A set of optimum exhaust designs have been obtained for each investigated engine and subsequently compared against their reciprocal baselines established using the current industry practice in terms of exhaust design. The obtained results indicate that the optimization could lead to designs with significant increase in net propulsive force, compared to their respective notional baselines. It is shown that the developed approach is implicitly able to identify and mitigate undesirable flow-features that may compromise the aerodynamic performance of the exhaust system. The proposed method enables the aerodynamic design of optimum separate-jet exhaust systems for a user-specified engine cycle, using only a limited set of standard nozzle design variables. Furthermore, it enables to quantify, correlate, and understand the aerodynamic behavior of any separate-jet exhaust system for any specified engine architecture. Hence, the overall framework constitutes an enabling technology toward the design of optimally configured exhaust systems, consequently leading to increased overall engine thrust and reduced specific fuel consumption (SFC).

scholarly journals The Objective Space and the Formulation of Design Requirement in Natural Laminar Flow Optimization

2020 ◽  
Vol 10 (17) ◽  
pp. 5943 ◽  
Author(s):  
Shuyue Wang ◽  
Cong Wang ◽  
Gang Sun
Keyword(s):  
Laminar Flow ◽  
Design Space ◽  
Principal Component ◽  
Aerodynamic Design ◽  
Design Requirement ◽  
Pressure Drag ◽  
Design Variables ◽  
Objective Space ◽  
Natural Laminar Flow ◽  
The Impact

Design requirement is as important in aerodynamic design as in other industries because it sets up the objective for the samples in design space to approach. Natural Laminar Flow (NLF) optimization belongs to the type of aerodynamic design problems featured by the combination of distinct aerodynamic performance, where the design requirement is often formulated in form of summation of laminar-related performance and pressure drag performance with different weight assignment according to different perspectives. However, the formulations are rather experience-oriented and are decided non-quantitatively. Inspired by data manipulation approaches in design space (spanned by design variables of geometrical representation parameters) in many aerodynamic designs, this paper proposes new formulations of design requirement in NLF optimization via consideration of objective space (projection of design space through aerodynamics) and shows the impact of the corresponding formulation of design requirement to the result of NLF optimization in cases of transonic airfoil and aero engine compressor blade design from two perspectives: Pareto front convergence and improving effect of accessory performance. The paper uses Principal Component Analysis (PCA) to obtain the eigenvectors of objective space to extract the intrinsic information about specific problem. The method is realized in two cases with satisfactory result.

scholarly journals Sensitivity Analysis and Technology Evaluation for a Roadable Personal Air Vehicle at the Conceptual Design Stage

2019 ◽  
Vol 9 (19) ◽  
pp. 4121 ◽  
Author(s):  
Kim ◽  
Yun ◽  
Hwang
Keyword(s):  
Conceptual Design ◽  
Design Space ◽  
Leading Edge ◽  
Sensitivity Analyses ◽  
Design Stage ◽  
Maximum Speed ◽  
Statistical Tool ◽  
Conceptual Design Stage ◽  
Design Variables ◽  
Air Vehicle

In this study, the technology identification, evaluation, and selection (TIES) method was implemented to explore an optimum design space appropriate for a personal air vehicle (PAV) at the conceptual design stage. A morphological matrix was employed to identify possible alternative configurations and performance targets. The Microsoft Excel add-in JMP, a commercial statistical tool, and a PAV sizing tool developed for this study were used for modelling and simulation. After the screening test, seven design variables having significant impacts on the design were finally chosen, specifically the range, maximum speed, cruise speed, cruise altitude, passengers, takeoff ground roll, and stall speed. Response surface equations (RSEs) were created as a function of the seven design variables. The generated RSEs were then used to perform a Monte Carlo simulation (MCS) to explore a feasible design space. As a result, it was confirmed that all seven design variables can be employed for an optimization process. In addition, k-factor and technology sensitivity analyses were conducted to evaluate applicable technologies quantitatively. Consequently, the selected set includes a flow circulation flap, leading edge blowing, a nanocoating, liquid metal, and an advanced composite material, which are technologies that greatly influenced the target criteria. Furthermore, the target value variations were analyzed as the k factors changed.

Multi-Objective Decision Making of a Simplified Car Body Shape Towards Optimum Aerodynamic Performance

2017 ◽  
Author(s):  
Kisun Song ◽  
Kyung Hak Choo ◽  
Jung-Hyun Kim ◽  
Dimitri N. Mavris
Keyword(s):  
Decision Making ◽  
Design Space ◽  
Fuel Efficiency ◽  
Aerodynamic Performance ◽  
Pareto Optimum ◽  
Car Body ◽  
Multi Objective ◽  
Design Variables ◽  
Driving Stability ◽  
Ahmed Body

The importance of the aerodynamic performance, specifically meaning reducing both drag coefficient (CD) and lift coefficient (CL), is a growing issue in the modern automotive industry. The former is to improve fuel efficiency whereas the latter is to improve driving stability. These characteristics are quite associated with the geometric details of the external car body such that many studies are putting a lot of efforts to understand the contribution of geometrical details to the aerodynamic performance. For the design point of view, the comparison among local shape factors and the following trade-off study are essential during the early stage of the exterior design. In this paper, the qualitative and quantitative contribution of local shapes to overall aerodynamic performance is explored with a simplified vehicle model, especially the Ahmed body, by performing a multi-objective design optimization in a high-speed cruising condition. To achieve the goal of this research, Computational Fluid Dynamics (CFD) analysis is incorporated with various state-of-the-art design methodologies such as Design of Experiments (DOE), surrogate modeling, sensitivity analysis, Pareto-Optimum decision making, etc. Six design variables around the rear shapes of the Ahmed body are parameterized and populated into design space via a hybrid DOE method combining Central Composite Design (CCD) and Latin Hypercube. For CD and CL, corresponding Artificial Neural Networks (ANN) are created for the surrogate model. Then, the individual and collaborative contributions of design variables are scrutinized. For further detailed analysis, a Monte Carlo Simulation (MCS) is performed so that the empirical joint probability distribution is calculated to explore the feasible and optimum design space. Based on the simulation and analysis results, Pareto frontier is identified and multi-objective optimization is conducted to seek the best appropriate vehicle shapes for different design goals between CD and CL, which weigh on fuel efficiency and driving stability, respectively.

Multi-Objective Optimization of an Autonomous Underwater Vehicle

2009 ◽  
Vol 43 (2) ◽  
pp. 48-60 ◽  
Author(s):  
M. Martz ◽  
W. L. Neu
Keyword(s):  
Design Space ◽  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Design Problems ◽  
Single Measure ◽  
Design Variables ◽  
Complex Design ◽  
Final Design ◽  
Undersea Vehicle ◽  
Hierarchy Process

AbstractThe design of complex systems involves a number of choices, the implications of which are interrelated. If these choices are made sequentially, each choice may limit the options available in subsequent choices. Early choices may unknowingly limit the effectiveness of a final design in this way. Only a formal process that considers all possible choices (and combinations of choices) can insure that the best option has been selected. Complex design problems may easily present a number of choices to evaluate that is prohibitive. Modern optimization algorithms attempt to navigate a multidimensional design space in search of an optimal combination of design variables. A design optimization process for an autonomous underwater vehicle is developed using a multiple objective genetic optimization algorithm that searches the design space, evaluating designs based on three measures of performance: cost, effectiveness, and risk. A synthesis model evaluates the characteristics of a design having any chosen combination of design variable values. The effectiveness determined by the synthesis model is based on nine attributes identified in the U.S. Navy’s Unmanned Undersea Vehicle Master Plan and four performance-based attributes calculated by the synthesis model. The analytical hierarchy process is used to synthesize these attributes into a single measure of effectiveness. The genetic algorithm generates a set of Pareto optimal, feasible designs from which a decision maker(s) can choose designs for further analysis.

Aerodynamic performance effects due to small leading-edge ice (roughness) on wings and tails

1993 ◽  
Vol 30 (6) ◽  
pp. 807-812 ◽  
Author(s):  
Walter O. Valarezo ◽  
Frank T. Lynch ◽  
Robert J. McGhee
Keyword(s):  
Leading Edge ◽  
Aerodynamic Performance ◽  
Ice Roughness ◽  
Performance Effects

Aerodynamic Efficiency Optimization of the 1st Stage of Transonic High Pressure Turbine through Lean and Sweep Angles

2019 ◽  
Vol 36 (3) ◽  
pp. 245-256
Author(s):  
Yoonki Kim ◽  
Sanga Lee ◽  
Kwanjung Yee ◽  
Young-Seok Kang
Keyword(s):  
High Pressure ◽  
Surrogate Model ◽  
Design Space ◽  
Latin Hypercube Sampling ◽  
Expected Improvement ◽  
Total Efficiency ◽  
High Pressure Turbine ◽  
Sweep Angle ◽  
Design Variables ◽  
Optimal Latin Hypercube Sampling

Abstract The purpose of this study is to optimize the 1st stage of the transonic high pressure turbine (HPT) for enhancement of aerodynamic performance. Isentropic total-to-total efficiency is designated as the objective function. Since the isentropic efficiency can be improved through modifying the geometry of vane and rotor blade, lean angle and sweep angle are chosen as design variables, which can effectively alter the blade geometry. The sensitivities of each design variable are investigated by applying lean and sweep angles to the base nozzle and rotor, respectively. The design space is also determined based on the results of the parametric study. For the design of experiment (DoE), Optimal Latin Hypercube sampling is adopted, so that 25 evenly distributed samples are selected on the design space. Sequentially, based on the values from the CFD calculation, Kriging surrogate model is constructed and refined using Expected Improvement (EI). With the converged surrogate model, optimum solution is sought by using the Genetic Algorithm. As a result, the efficiency of optimum turbine 1st stage is increased by 1.07 % point compared to that of the base turbine 1st stage. Also, the blade loading, pressure distribution, static entropy, shock structure, and secondary flow are thoroughly discussed.

Heat Transfer and Flowfield Measurements in the Leading Edge Region of a Stator Vane Endwall

1999 ◽  
Vol 121 (3) ◽  
pp. 558-568 ◽  
Author(s):  
M. B. Kang ◽  
A. Kohli ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Edge Region ◽  
Leading Edge Vortex ◽  
Stator Vane ◽  
Edge Vortex ◽  
The Mean

The leading edge region of a first-stage stator vane experiences high heat transfer rates, especially near the endwall, making it very important to get a better understanding of the formation of the leading edge vortex. In order to improve numerical predictions of the complex endwall flow, benchmark quality experimental data are required. To this purpose, this study documents the endwall heat transfer and static pressure coefficient distribution of a modern stator vane for two different exit Reynolds numbers (Reex = 6 × 105 and 1.2 × 106). In addition, laser-Doppler velocimeter measurements of all three components of the mean and fluctuating velocities are presented for a plane in the leading edge region. Results indicate that the endwall heat transfer, pressure distribution, and flowfield characteristics change with Reynolds number. The endwall pressure distributions show that lower pressure coefficients occur at higher Reynolds numbers due to secondary flows. The stronger secondary flows cause enhanced heat transfer near the trailing edge of the vane at the higher Reynolds number. On the other hand, the mean velocity, turbulent kinetic energy, and vorticity results indicate that leading edge vortex is stronger and more turbulent at the lower Reynolds number. The Reynolds number also has an effect on the location of the separation point, which moves closer to the stator vane at lower Reynolds numbers.

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