Numerical study of the flow-induced sunroof buffeting noise of a simplified cavity model based on the slightly compressible model

2013 ◽  
Vol 227 (8) ◽  
pp. 1187-1199 ◽  
Author(s):  
Yiping Wang ◽  
Yadong Deng ◽  
Zhendong Yang ◽  
Tao Jiang ◽  
Chuqi Su ◽  
...  
Keyword(s):  
Numerical Study ◽  
Cavity Model ◽  
Slightly Compressible ◽  
Model Based ◽  
Sunroof Buffeting Noise

Cavity Model-based Analysis of Field Propagation in a six-port Riblet-type Directional Coupler

2018 ◽  
Vol 37 (1) ◽  
pp. 24-35
Author(s):  
Ashmi Chakraborty Das ◽  
Santanu Dwari ◽  
Sonika Priyadarsini Biswal
Keyword(s):  
Directional Coupler ◽  
Cavity Model ◽  
Model Based ◽  
Model Based Analysis

scholarly journals Nonlinear Error Propagation Analysis of a New Family of Model-Based Integration Algorithm for Pseudodynamic Tests

2018 ◽  
Vol 10 (8) ◽  
pp. 2846
Author(s):  
Bo Fu ◽  
Huanjun Jiang ◽  
Tao Wu
Keyword(s):  
Error Propagation ◽  
Numerical Study ◽  
Integration Algorithm ◽  
Amplification Factors ◽  
Model Based ◽  
New Family ◽  
Pseudodynamic Test ◽  
Error Amplification ◽  
Propagation Properties ◽  
New Algorithms

Error propagation properties of integration algorithms are crucial in conducting pseudodynamic tests. The motivation of this study is to investigate the error propagation properties of a new family of model-based integration algorithm for pseudodynamic tests. To develop the new algorithms, two additional coefficients are introduced in the Chen-Ricles (CR) algorithm. In addition, a parameter—i.e., degree of nonlinearity—is applied to describe the change of stiffness for nonlinear structures. The error propagation equation for the new algorithms implemented in a pseudodynamic test is derived and two error amplification factors are deduced correspondingly. The error amplification factors for three structures with different degrees of nonlinearity are calculated to illustrate the error propagation effect. The numerical simulation of a pseudodynamic test for a two-story shear-type building structure is conducted to further demonstrate the error propagation characteristics of the new algorithms. It can be concluded from the theoretical analysis and numerical study that both nonlinearity and the two additional coefficients of the new algorithms have great influence on its error propagation properties.

scholarly journals Model-based Acceleration Control of Turbofan Engines with a Hammerstein-Wiener Representation

2017 ◽  
Vol 34 (2) ◽  
Author(s):  
Jiqiang Wang ◽  
Zhifeng Ye ◽  
Zhongzhi Hu ◽  
Xin Wu ◽  
Georgi Dimirovsky ◽  
...  
Keyword(s):  
Numerical Study ◽  
Design Method ◽  
Minimum Variance ◽  
Aviation Industry ◽  
Control Law ◽  
Wiener Model ◽  
Control Techniques ◽  
Turbofan Engines ◽  
Model Based ◽  
Widespread Acceptance

AbstractAcceleration control of turbofan engines is conventionally designed through either schedule-based or acceleration-based approach. With the widespread acceptance of model-based design in aviation industry, it becomes necessary to investigate the issues associated with model-based design for acceleration control. In this paper, the challenges for implementing model-based acceleration control are explained; a novel Hammerstein-Wiener representation of engine models is introduced; based on the Hammerstein-Wiener model, a nonlinear generalized minimum variance type of optimal control law is derived; the feature of the proposed approach is that it does not require the inversion operation that usually upsets those nonlinear control techniques. The effectiveness of the proposed control design method is validated through a detailed numerical study.

scholarly journals Numerical Study on Optics and Heat Transfer of Solar Reactor for Methane Thermal Decomposition

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6451
Author(s):  
Haneol Kim ◽  
Jongkyu Kim
Keyword(s):  
Heat Loss ◽  
Conversion Rate ◽  
Numerical Study ◽  
Solar Furnace ◽  
Cavity Model ◽  
Porous Catalyst ◽  
Reduce Heat Loss ◽  
Fraction Distribution ◽  
Main Component ◽  
Thermal Sources

This study aims to reduce greenhouse gas emissions to the atmosphere and effectively utilize wasted resources by converting methane, the main component of biogas, into hydrogen. Therefore, a reactor was developed to decompose methane into carbon and hydrogen using solar thermal sources instead of traditional energy sources, such as coal and petroleum. The optical distributions were analyzed using TracePro, a Monte Carlo ray-tracing-based program. In addition, Fluent, a computational fluid dynamics program, was used for the heat and mass transfer, and chemical reaction. The cylindrical indirect heating reactor rotates at a constant speed to prevent damage by the heat source concentrated at the solar furnace. The inside of the reactor was filled with a porous catalyst for methane decomposition, and the outside was surrounded by insulation to reduce heat loss. The performance of the reactor, according to the cavity model, was calculated when solar heat was concentrated on the reactor surface and methane was supplied into the reactor in an environment with a solar irradiance of 700 W/m2, wind speed of 1 m/s, and outdoor temperature of 25 °C. As a result, temperature, methane mass fraction distribution, and heat loss amounts for the two cavities were obtained, and it was found that the effect on the conversion rate was largely dependent on a temperature over 1000 °C in the reactor. Moreover, the heat loss of the full-cavity model decreased by 12.5% and the methane conversion rate increased by 33.5%, compared to the semi-cavity model. In conclusion, the high-temperature environment of the reactor has a significant effect on the increase in conversion rate, with an additional effect of reducing heat loss.

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