Effusion Cooling 3D Simulations to Establish a Discharge Coefficient Correlation

2017 ◽  
Author(s):  
Nicolas Savary ◽  
Thibaud Aupoix ◽  
Patrick Duchaine ◽  
Guillaume Cottin
Keyword(s):  
Cross Section ◽  
Discharge Coefficient ◽  
Effective Cross Section ◽  
Sensitivity Study ◽  
Design Parameters ◽  
Detailed Model ◽  
3D Simulations ◽  
Wide Range ◽  
Cooling Design ◽  
Physical Phenomena

Effusion cooling is one of the most widespread system used to cool combustion chamber liners nowadays: it is efficient, cheap and light. Effusion cooling consists of drilling thousands of submillimetric holes into the combustor wall in order to cool it down from inside the holes and create a cooling film inside the combustor protecting it from the hot gases. Effusion cooling has long time been very challenging for combustor simulations because it involves lengthscales ranging from ½ millimeter (about the size of the effusion holes) to ½ meter (about the diameter of the combustor). That is one of the main reasons for which 3D simulations of effusion cooling has long been inaccessible, and has generated the studies presented in this paper. This study will focus on the effusion cooling holes discharge coefficient evaluation as a function of numerous aerothermal and design parameters. Many attempts to describe aerodynamically effusion have occurred, mainly based on experiments exploring few of the parameters mentioned above. But none of these studies tried to elaborate a model able to handle most of them. This is the purpose of this study which will set up a 3D model able to describe finely the physical phenomena involved in combustor effusion cooling holes and the influence of the design parameters available to combustor engineers on these phenomena. The strategy which prevails in the setup of the numerical 3D detailed model is to find a compromise between the reliability and the CPU cost of the simulation. Indeed the objective is to study the influence of a wide range of effusion cooling design parameters such as hole diameter, orientation, shape, etc. . . on the effective cross section. In addition, for a better understanding of the physical phenomena, all the simulations are performed at the same aerothermal conditions. These aerothermal conditions as blowing ratio, cooling temperature, pressure are not design parameters of effusion cooled walls. They are usually imposed by the gas turbine thermodynamic cycle very early in the development of a new engine. A preliminary study allowed to select the parameters which were both the least known and the most influential on the effusion hole mass flowrate according to literature, preexisting numerical and experimental databases. More than 60 new CFD simulations have been performed and show the influence of each effusion cooling design parameter taken separately: effusion holes inclination, orientation and taper angle. A mesh sensitivity study has been performed in order to validate the numerical approach. Then, the analysis of both the preexisting data and this new numerical database showed that some of the design parameters have strong effects and coupled influences on the mass flow rate through the holes. On the other hand, some other parameters could be easily described by simple models or even neglected. This study concludes by quantifying the improvement of a proprietary effective cross section correlation of effusion cooled walls, based on the analysis mentioned in this study.

Combustor Effusion Cooling Multiparameter Aerothermal Numerical Analysis

2016 ◽  
Author(s):  
Nicolas Savary ◽  
Guillaume Cottin ◽  
Robin Herve
Keyword(s):  
Thermodynamic Cycle ◽  
Nonlinear Effects ◽  
Design Parameters ◽  
Detailed Model ◽  
Transfer Factors ◽  
Combustion Gases ◽  
Wide Range ◽  
Pattern Length ◽  
Cooling Design ◽  
Physical Phenomena

The solid temperature prediction is one of the most widespread type of modelization used in the industry. One reading this study might wonder why there would be readymade solutions for many industries and why they would not fit for combustor wall temperatures calculation. The specificity of state-of-the-art and future combustors is the massive use of effusion cooling for its thermal management. Effusion cooling consists of drilling thousands of sub millimetric holes into the combustor wall in order to cool it from inside the holes and create a cooling film inside the combustor protecting its wall from the hot combustion gases. Effusion cooling has long time been very challenging for combustor simulations because it involves length scales ranging from ½ millimeter (about the size of the effusion holes) to ½ meter (about the diameter of the combustor). That is one of the main reasons for which 3D simulations of an effusion cooled combustor wall temperature has long been inaccessible, and has generated the studies presented in this paper. This study focuses on setting up a 3D model able to describe finely the physical phenomena involved in combustor effusion cooling and the influence of the design parameters available to combustor engineers on these phenomena. The final goal is to use the knowledge generated in this study to create or improve existing uniform effusion cooling thermal models developed by several teams. The logic which prevails in the setup of the numerical 3D detailed model is to find a compromise between the reliability and the CPU cost of the simulation. Indeed the objective is to study the influence of a very wide range of effusion cooling design parameters such as hole diameter, orientation, pattern, length, etc... on the cooling effectiveness. In addition, for a better understanding of the physical phenomena, all the simulations are performed at the same aerothermal conditions. These aerothermal conditions as blowing ratio, cooling temperature, pressure are not design parameters of effusion cooled walls. They are usually imposed by the gas turbine thermodynamic cycle very early in the development of a new engine. More than 30 CFD simulations have been performed and show the influence of each effusion cooling design parameter taken separately: effusion holes density, angle with respect to the combustor wall, orientation with respect to the main flow, pattern at a fixed density, and diameter. Some of these simulations have been compared to experimental results in order to validate the global numerical method. Then, the analysis of this design of experiment showed that some of the design parameters have strongly nonlinear effects and coupled influences on the wall cooling and on the aerothermal phenomena involved. On the other hand, the simulations show that the effect of some other parameters could be easily described by simple models or even neglected. This study concludes by giving a summary of the design parameters influence on the heat transfer factors to be modeled in a full uniform effusion cooling thermal model, taking into account the cooling / heating on the three sides of the wall: - on the cool side - inside the effusion holes - on the hot side, inside the combustor

scholarly journals Aerodynamic Performance of Biomimicry Snake-Shaped Airfoil

2019 ◽  
Vol 9 (2) ◽  
pp. 3319-3323
Keyword(s):  
Cross Section ◽  
Lift Coefficient ◽  
Design Parameters ◽  
Drag Forces ◽  
Cross Section Shape ◽  
Section Shape ◽  
Wide Range ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The cross-section shape and proportionality between geometrical dimensions are the most important design parameters of any lifting surfaces. These parameters affect the amount of the aerodynamic forces that will be generated. In this study, the focus is placed on the snake-cross-section airfoil known as the S-airfoil. It is found that there is a lack of available researches on S-airfoil despite its important characteristics. A parametric study on empty model of the S-airfoil with a cross-section shape that is inspired by the Chrysopelea paradise snake is conducted through numerical simulation. Simulation using 2D-ANSYS FLUENT17 software is used to generate the lift and drag forces to determine the performance of airfoil aerodynamic. Based on the results, the S-airfoil can be improved in performance of aerodynamic by reducing the thickness at certain range, whereby changing the thickness-to-chord ratio from 0.037 to 0.011 results in the increment of lift-to-drag ratio from 2.629 to 3.257. On other hand, increasing the height-to-chord ratio of the S-airfoil will increase maximum lift coefficient but drawback is a wide range of angles of attack regarding maximum lift-to-drag ratio. Encouraging results obtained in this study draws attention to the importance of expanding the research on S-airfoil and its usage, especially in wind energy.

PECULIARITIES OF USING THE VERTICAL ROTARY CULTIVATOR FOR INTER-ROW SOIL TILLAGE OF RASPBERRY PLANTINGS [

2021 ◽  
pp. 20-24
Author(s):  
VIKTOR N. OZHERELYEV ◽  
Keyword(s):  
Cross Section ◽  
Inclination Angle ◽  
Lateral Displacement ◽  
Design Parameters ◽  
Row Spacing ◽  
Strip Surface ◽  
Air Jet ◽  
Wide Range ◽  
Row Width ◽  
The Cross

When tilling the soil with a vertical-rotary limiter of the raspberry row width, rotating knives perform its transverse transferring. In this regard, it is advisable to fi nd the means to control the process. The study revealed the infl uence of the design parameters of the raspberry row width limiter on the pattern and degree of the lateral displacement of the cross-section of the cultivated soil strip. The authors assessed the intensity of the process of transverse soil redistribution by comparing the positions of the gravity centers of the treated strip cross-section before and after the tillage operation. The studies analyzed medium and heavy loams with a humus content of less than 2.5% and a wide range of variation in moisture content and contamination of the treated strip. With a rotor diameter of about 900 mm, the lateral displacement of the gravity center of the strip cross-section varies within the range of 50…100 mm. The authors found that the lateral displacement control of the soil layer is possible at a constant forward inclination angle of the rotation axis of the knife rotor, which is equal to 18º. This can be done by changing the lateral inclination angle of the specifi ed axis towards the row spacing center in the range between 10 and 20º. As a result, a signifi cant portion of the discarded soil returns to the treated strip surface, minimizing its outside throw-off and eliminating the possibility of injuring the raspberry shoots. The limiter proposed by the authors has a longitudinal baffl e installed at an angle to the vertical with a minimum energy intensity of the process. It helps to maintain the cross-section of the surface of the row spacing of raspberries in a leveled state throughout the entire life of the plantation.possibility of ensuring the maximum propagation range of a non-isothermal supply air jet by angular correction of the fl ow vector at the outlet of the ventilation unit. Based on the theory of free air distribution, the author analyzed and graphically visualized the fl ow trajectories of the supply air from the combined climate control unit with heat recovery in the production room in the range of outdoor temperatures from +10 to –40°C. Given the time period of outdoor temperatures, fl at sections of a three-dimensional graph were built with a step of 10°C in the range from +10 to –30°C. The author found that the maximum service area of the installation is limited by the propagation range of the supply air jet. The area can be increased by changing the direction of the fl ow vector by an angle ranging between 0 and 34°. The value of the inclination angle of the fl ow vector of the supply air jet is determined by the obtained approximation dependency. Considering the regulation of the fl ow vector, the author used the formula of M.Z. Pechatnikov to determine the propagation range of a limited axisymmetric jet. The studies carried out made it possible to establish the relationship between the propagation range of the supply air jet of the installation and the outside temperature, the inclination angle of the fl ow vector, and the theoretical variation range of the inclination angle of the fl ow vector, ranging between 0 and 34°.

EFFECTS OF SPACE CHARGE ON THE "EFFECTIVE CROSS SECTION"

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-755-C7-756
Author(s):  
N. S. Kopeika ◽  
T. Karcher ◽  
C.S. Ih.
Keyword(s):  
Space Charge ◽  
Cross Section ◽  
Effective Cross Section

Extending the Applicability of the ANI Deep Learning Molecular Potential to Sulfur and Halogens

2020 ◽  
Author(s):  
Christian Devereux ◽  
Justin Smith ◽  
Kate Davis ◽  
Kipton Barros ◽  
Roman Zubatyuk ◽  
...  
Keyword(s):  
Drug Development ◽  
Autonomous Vehicles ◽  
Potential Energy Surfaces ◽  
Organic Molecules ◽  
Chemical Elements ◽  
Molecular Potential ◽  
Wide Range ◽  
Energy Surfaces ◽  
New Applications ◽  
Physical Phenomena

<p>Machine learning (ML) methods have become powerful, predictive tools in a wide range of applications, such as facial recognition and autonomous vehicles. In the sciences, computational chemists and physicists have been using ML for the prediction of physical phenomena, such as atomistic potential energy surfaces and reaction pathways. Transferable ML potentials, such as ANI-1x, have been developed with the goal of accurately simulating organic molecules containing the chemical elements H, C, N, and O. Here we provide an extension of the ANI-1x model. The new model, dubbed ANI-2x, is trained to three additional chemical elements: S, F, and Cl. Additionally, ANI-2x underwent torsional refinement training to better predict molecular torsion profiles. These new features open a wide range of new applications within organic chemistry and drug development. These seven elements (H, C, N, O, F, Cl, S) make up ~90% of drug like molecules. To show that these additions do not sacrifice accuracy, we have tested this model across a range of organic molecules and applications, including the COMP6 benchmark, dihedral rotations, conformer scoring, and non-bonded interactions. ANI-2x is shown to accurately predict molecular energies compared to DFT with a ~10<sup>6</sup> factor speedup and a negligible slowdown compared to ANI-1x. The resulting model is a valuable tool for drug development that can potentially replace both quantum calculations and classical force fields for myriad applications.</p>

Optimization Analysis of the Wedge Block Surface of NYD Contact Backstop

2013 ◽  
Vol 433-435 ◽  
pp. 2277-2281
Author(s):  
Quan Wei Wang ◽  
Ming Hui Wang ◽  
Dong Li ◽  
Dian Mao Wan ◽  
Rong Meng
Keyword(s):  
Cross Section ◽  
Design Parameters ◽  
Optimization Analysis ◽  
Archimedes Spiral ◽  
The Cross ◽  
Section Curve ◽  
Relationship Of ◽  
The Relationship

By analyzing the relationship of the design parameters of NYD contact backstop, the cross-section curve of the wedge block has been discussed as Archimedes spiral, logarithm spiral and arc. Each curve is designed optimally using MATLAB optimization toolbox. The merits and drawbacks of each curve are discussed.

scholarly journals Multi-stable composite twisting structure for morphing applications

2012 ◽  
Vol 468 (2141) ◽  
pp. 1230-1251 ◽  
Author(s):  
X. Lachenal ◽  
P. M. Weaver ◽  
S. Daynes
Keyword(s):  
Analytical Model ◽  
Material Properties ◽  
Degrees Of Freedom ◽  
Design Parameters ◽  
Engineering Structures ◽  
The Past ◽  
Wide Range ◽  
Morphing Structure ◽  
Low Mass ◽  
Unstable States

Conventional shape-changing engineering structures use discrete parts articulated around a number of linkages. Each part carries the loads, and the articulations provide the degrees of freedom of the system, leading to heavy and complex mechanisms. Consequently, there has been increased interest in morphing structures over the past decade owing to their potential to combine the conflicting requirements of strength, flexibility and low mass. This article presents a novel type of morphing structure capable of large deformations, simply consisting of two pre-stressed flanges joined to introduce two stable configurations. The bistability is analysed through a simple analytical model, predicting the positions of the stable and unstable states for different design parameters and material properties. Good correlation is found between experimental results, finite-element modelling and predictions from the analytical model for one particular example. A wide range of design parameters and material properties is also analytically investigated, yielding a remarkable structure with zero stiffness along the twisting axis.

Closed-Form Correlation of Buildings Energy Use With Key Design Parameters Calibrated Using a Genetic Algorithm

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Raed I. Bourisli ◽  
Adnan A. AlAnzi
Keyword(s):  
Genetic Algorithm ◽  
Closed Form ◽  
Energy Use ◽  
Building Design ◽  
Office Buildings ◽  
Design Parameters ◽  
Wide Range ◽  
Variable Function ◽  
Real Coded Genetic Algorithm ◽  
The Difference

This work aims at developing a closed-form correlation between key building design variables and its energy use. The results can be utilized during the initial design stages to assess the different building shapes and designs according to their expected energy use. Prototypical, 20-floor office buildings were used. The relative compactness, footprint area, projection factor, and window-to-wall ratio were changed and the resulting buildings performances were simulated. In total, 729 different office buildings were developed and simulated in order to provide the training cases for optimizing the correlation’s coefficients. Simulations were done using the VisualDOE TM software with a Typical Meteorological Year data file, Kuwait City, Kuwait. A real-coded genetic algorithm (GA) was used to optimize the coefficients of a proposed function that relates the energy use of a building to its four key parameters. The figure of merit was the difference in the ratio of the annual energy use of a building normalized by that of a reference building. The objective was to minimize the difference between the simulated results and the four-variable function trying to predict them. Results show that the real-coded GA was able to come up with a function that estimates the thermal performance of a proposed design with an accuracy of around 96%, based on the number of buildings tested. The goodness of fit, roughly represented by R2, ranged from 0.950 to 0.994. In terms of the effects of the various parameters, the area was found to have the smallest role among the design parameters. It was also found that the accuracy of the function suffers the most when high window-to-wall ratios are combined with low projection factors. In such cases, the energy use develops a potential optimum compactness. The proposed function (and methodology) will be a great tool for designers to inexpensively explore a wide range of alternatives and assess them in terms of their energy use efficiency. It will also be of great use to municipality officials and building codes authors.

Application areas of the angle reflector

2021 ◽  
pp. 54-59
Author(s):  
L. R. Yurenkova ◽  
O. A. Yakovuk ◽  
I. V. Morozov
Keyword(s):  
Radio Wave ◽  
Outer Space ◽  
Road Transport ◽  
Optical Systems ◽  
Design Parameters ◽  
Design Activity ◽  
Primary Role ◽  
Beam Laser ◽  
Wide Range ◽  
Graphical Calculation

The article provides examples of how the device known as the «angle reflector» a few decades ago has been increasingly used in various fields of science and technology in recent years. Angle reflectors are designed to change (reflect) optical and radar rays in the direction, opposite to the original direction. At present, angle reflectors are widely used to ensure the safety of road transport on dangerous road sections. Radio wave reflectors have the same design as optical ones; therefore, in radio detection and location, angle reflectors are used to send warning signals to ship radars on bridge supports, beacons and buoys. Modern angle reflectors attached to meteorological probes allow determining the direction and speed of the wind at high altitude, which is especially important in the study of the outer space. In recent years, devices have been developed to improve the accuracy of radar stations calibration. The examples of graphical calculation of angle reflectors presented in the article clearly demonstrate the primary role of geometry in the design activity of an engineer. The graphical calculation is based on the theoretical positions of projective geometry. The design and calculation of optical systems is carried out by the graphoanalytic method, since only with a combination of graphical and analytical methods it is possible to accurately calculate the course of a light beam, laser, or radio wave and thereby determine the design parameters of the devices. The article focuses on a graphical method for calculating two types of angle reflectors using orthogonal projection, due to which modern engineers will be able to create more up-to-date designs of optical systems with a wide range of applications.

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