Numerical Simulation of Axisymmetric Jet Screech Tones Using a General Purpose Finite-Volume CFD Code

Author(s):  
Konstantin Kurbatskii
2017 ◽  
Vol 45 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Alexey Mazin ◽  
Alexander Kapustin ◽  
Mikhail Soloviev ◽  
Alexander Karanets

ABSTRACT Numerical simulation based on finite element analysis is now widely used during the design optimization of tires, thereby drastically reducing the time investment in the design process and improving tire performance because it is obtained from the optimized solution. Rubber material models that are used in numerical calculations of stress–strain distributions are nonlinear and may include several parameters. The relations of these parameters with rubber formulations are usually unknown, so the designer has no information on whether the optimal set of parameters is reachable by the rubber technological possibilities. The aim of this work was to develop such relations. The most common approach to derive the equation of the state of rubber is based on the expansion of the strain energy in a series of invariants of the strain tensor. Here, we show that this approach has several drawbacks, one of which is problems that arise when trying to build on its basis the quantitative relations between the rubber composition and its properties. An alternative is to use a series expansion in orthogonal functions, thereby ensuring the linear independence of the coefficients of elasticity in evaluation of the experimental data and the possibility of constructing continuous maps of “the composition to the property.” In the case of orthogonal Legendre polynomials, the technique for constructing such maps is considered, and a set of empirical functions is proposed to adequately describe the dependence of the parameters of nonlinear elastic properties of general-purpose rubbers on the content of the main ingredients. The calculated sets of parameters were used in numerical tire simulations including static loading, footprint analysis, braking/acceleration, and cornering and also in design optimization procedures.


2011 ◽  
Vol 279 ◽  
pp. 181-185 ◽  
Author(s):  
Guo Hua Zhao ◽  
Qing Lian Shu ◽  
Bo Sheng Huang

This paper proposes a material model of AS4/PEEK, a typical thermoplastic composite material, for the general purpose finite element code—ANSYS, which can be used to predict the mechanical behavior of AS4/PEEK composite structures. The computational result using this model has a good agreement with the test result. This investigation can lay the foundation for the numerical simulation of thermoplastic composite structures.


Author(s):  
Ken Shimojima ◽  
Yoshikazu Higa ◽  
Osamu Higa ◽  
Ayumi Takemoto ◽  
Shigeru Itoh ◽  
...  

Recently, National Institute of Technology, Okinawa College (ONCT) has been developing a new food processing method using underwater shock wave. The continuous-operation device was manufactured for the production of rice flour, the amount of milling flour per hour and the quality of the rice powder were evaluated. In the case of Yuzu (Citrus junos), an improved fragrance was obtained using this methods compared with other general processing method. The authors have also developed a batch-type crushing device (pressure vessel) for various food processing. However, the mechanism by which is processed using shock waves has not been clarified. Therefore, in this study, the propagation characteristics of a shock wave in the developed pressure vessel were evaluated by numerical simulation. The characteristics of processing is evaluated using shock wave and, the pressure resistance of the vessel was analyzed. In addition, food processing experiments using the developed device were performed. In which, in which “Yuzu” were crushed. Yuzu before-and-after crushing were compared, and the effect of shock wave were clarified.


2014 ◽  
Vol 7 (2) ◽  
pp. 83-92 ◽  
Author(s):  
J. Fernández-Pato ◽  
P. García-Navarro

Abstract. The most commonly used hydraulic network models used in the drinking water community exclusively consider fully filled pipes. However, water flow numerical simulation in urban pipe systems may require to model transitions between surface flow and pressurized flow in steady and transient situations. The governing equations for both flow types are different and this must be taken into account in order to get a complete numerical model for solving dynamically transients. In this work, a numerical simulation tool is developed, capable of simulating pipe networks mainly unpressurized, with isolated points of pressurization. For this purpose, the mathematical model is reformulated by means of the Preissmann slot method. This technique provides a reasonable estimation of the water pressure in cases of pressurization. The numerical model is based on the first order Roe's scheme, in the frame of finite volume methods. The novelty of the method is that it is adapted to abrupt transient situations, with subcritical and supercritical flows. The validation has been done by means of several cases with analytic solutions or empirical laboratory data. It has also been applied to some more complex and realistic cases, like junctions or pipe networks.


2012 ◽  
Vol 236-237 ◽  
pp. 632-635
Author(s):  
Yue Sun ◽  
Yue Nan Chen ◽  
Zhi Yun Wang

In two-dimensional space, an elasto-plastic finite element computational model was established to simulate inner support for excavation on the basis of the general-purpose finite element software ABAQUS. The soil was assumed to be a uniform and normally consolidated clay layer and strut was discreted by spring element. Compared with published case study, it can be concluded that FEM software AQAQUS can present one reliable simulation progress of inner support for excavation.


Author(s):  
Tsuyoshi Kondo ◽  
Tsuguhiko Nakagawa

Diesel engine has some advantages that thermal efficiency is high and control response is fast. On the other hand, more particulate matter (PM) and nitrogen oxide (NOx) are contained in the exhaust gas of diesel engine. Premixed charge compression ignition (PCCI) combustion is proposed to reduce the PM and NOx. In the lean range of equivalent ratio, unburned fuel is left and in the rich range, PM and soot are generated. For the practical use of PCCI combustion, mixing fuel and air well is important under the low equivalent ratio of injection. In this study, the mixing characteristics of fuel and air in a cylinder were numerically evaluated. A numerical simulation was performed with general-purpose simulator. The fuel has been injected into the vertical direction of cylinder and injection angle has been defined as 0 degree. In order to express the collusion, impingement on the wall model, that defines behavior of a droplet impinged on the wall with the Weber number of a droplet, was applied. By the injection timing, standard deviation of local equivalent ratio at Top Dead Center (TDC) was plotted. In this study, Frequency of mixing in each cell statistically was observed to evaluate the fuel-air mixing degree. The authors have taken notice of the condition which can be reduced the amount of scatter in the distribution of local equivalent ratio.


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