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Zhang Y.F.,French National Center for Scientific Research | Zhang Y.F.,AVIC Commercial Aircraft Engine Co. | Vicquelin R.,French National Center for Scientific Research
Journal of Computational Physics | Year: 2016

Bulk Reynolds number and bulk temperature are key quantities when reporting results in channel flow simulations. There are situations when one wishes to accurately control these parameters while changing some numerical or physical conditions. A method to control the bulk Reynolds number and the bulk temperature in channel flow simulations is detailed. An ordinary differential equation is prescribed for the additional source term in the momentum balance equation so that the transient regime of the simulation is thoroughly tuned in order to efficiently and accurately reach the target Reynolds number value. A similar treatment is applied for the additional volume heat source term in the energy balance equation. The proposed method is specifically interesting when studying complex multi-physics in channel flow configurations when non-dimensionalization of the equations is no longer practical. © 2015 Elsevier Inc. Source

Sun X.,Beihang University | Jiang Y.,Beihang University | Liang A.,AVIC Commercial Aircraft Engine Co. | Jing X.,Beihang University
Journal of the Acoustical Society of America | Year: 2012

An immersed boundary computational model is presented in order to deal with the acoustic scattering problem by complex geometries, in which the wall boundary condition is treated as a direct body force determined by satisfying the non-penetrating boundary condition. Two distinct discretized grids are used to discrete the fluid domain and immersed boundary, respectively. The immersed boundaries are represented by Lagrangian points and the direct body force determined on these points is applied on the neighboring Eulerian points. The coupling between the Lagrangian points and Euler points is linked by a discrete delta function. The linearized Euler equations are spatially discretized with a fourth-order dispersion-relation-preserving scheme and temporal integrated with a low-dissipation and low-dispersion Runge-Kutta scheme. A perfectly matched layer technique is applied to absorb out-going waves and in-going waves in the immersed bodies. Several benchmark problems for computational aeroacoustic solvers are performed to validate the present method. © 2012 Acoustical Society of America. Source

Liang A.,AVIC Commercial Aircraft Engine Co.
Procedia Engineering | Year: 2015

A frequency domain Immersed Boundary (IB) method was developed and validated in the present paper using 2-dimenstional acoustical radiation and scattering cases. The IB method was incorporated with Linearized Euler Equations (LEE) in the frequency domain in the present work. The governing equations were spatially discretisized using the DRP scheme. A pseudo time dependant term was added to the frequency domain equations, allowing the use of a conventional time-marching algorithm to converge the solutions in the pseudo-time domain. Perfectly Matched Layers (PML) were placed at boundaries of computational domain where non-reflective conditions were expected. PML technique was also implemented inside the rigid body to stabilize the computation. The impermeable boundary condition on the surface of the geometry is guaranteed by finding the inverse of an influence matrix, which establishes the relationship between boundary forces and induced velocity. Numerical computations were performed for 2-dimensional acoustic radiation and scattering problems. Computational results were compared with exact solution and yielded good agreement, providing a solid validation of the current method. The method is expected to extend to higher dimension and applied to more complex problem like wake/airfoil interaction simulations in turbomachinery. © 2015 The Authors. Source

Jin T.,Zhejiang University | Luo K.,Zhejiang University | Lu S.,Zhejiang University | Lu S.,AVIC Commercial Aircraft Engine Co. | Fan J.,Zhejiang University
International Journal of Hydrogen Energy | Year: 2013

Direct numerical simulation (DNS) of a three-dimensional spatially-developing supersonic lifted hydrogen jet flame has been conducted in this paper. The scalar structure of the lifted flame is investigated through instantaneous images and conditional means of combustion statistics. And then the scalar dissipation rate and its implications on the flamelet-based combustion modeling are analyzed in detail. It can be found that most of the heat release occurs in the subsonic region. However, distributed reaction pockets exist in the sonic mixing layer due to the rolled up vortices. The magnitude of conditional compression or expansion rate of the fluid presents comparable to the corresponding heat release rate, and takes a great influence on the flame temperature in the high speed reacting flow. The probability density functions of mean conditional and unconditional scalar dissipation rate prove to qualitatively agree with the presumed log-normal distribution, while a little skewed to the higher scalar dissipation rate in the sonic mixing layer. The conditional mean scalar dissipation rate presents to be radial dependent at the flame base, especially in the fuel lean mixture. The DNS results show good agreement with the trends of the flamelet calculations; however, the amplitudes of temperature are far lower than the corresponding flamelet statistics due to finite rate reaction and expansion of the high speed reacting flow. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Wu B.,Northwestern Polytechnical University | Yan X.,AVIC Commercial Aircraft Engine Co. | Luo M.,Northwestern Polytechnical University | Gao G.,Northwestern Polytechnical University
Chinese Journal of Aeronautics | Year: 2013

A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other. © 2013 Production and hosting by Elsevier Ltd. on behalf of CSAA & BUAA. Source

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