توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱CFD Calculation of Axially Symmetric Supercavities
نویسنده(ها): ، ، ،
اطلاعات انتشار: هفتمین همایش انجمن هوافضای ایران، سال
تعداد صفحات: ۷
Engineering interest in natural and ventilated cavities about submerged bodies and in turbomachinery has led researchers to study and attempt to model large scale cavitation for decades. Comparatively simple analytical methods have been used widely and successfully to model developed cavitation, since the hydrodynamics of these flows are often dominated by irrotational and rotational inviscid effects. However, a range of more complex physical phenomena are often associated with such cavities, including viscous effects, unsteadiness, mass transfer, threedimensionality and compressibility. Through some of these complicating physics can be accommodated in simpler physical models, the ongoing maturation and increased generality of multiphase Computational Fluid Dynamic (CFD) methods has motivated recent research by a number of groups in the application of these methods for developed cavitation analysis. In this paper the numerical simulation of supercavitating flow was performed. The flow was assumed isothermal and consists of two phases, liquid and its vapor. A transport equation based cavitation model was used for the numerical simulation of the flow field including natural supercavitation. A mass transfer between the phases is treated as a source and sink terms in vapor transport equation. The numerical method is used for different geometries in a wide range of cavitation numbers. The cavity parameters such as cavity length and cavity width were compared with experimental data and agreed very closely.<\div>

۲An iterative algorithm based on vapor phase’s artificial viscosity for simulating natural supercavitation
نویسنده(ها): ، ، ،
اطلاعات انتشار: یازدهمین کنفرانس دینامیک شاره ها، سال
تعداد صفحات: ۷
In this paper the numerical simulation of supercavitating flow was performed. The flow was assumed isothermal and consists of two phases, liquid and its vapor. A transport equation based cavitation model was used for the numerical simulation of the flow field including natural supercavitation. A mass transfer between the phases is treated as a source and sink terms in vapor transport equation. The numerical method is used for different geometries in a wide range of cavitation numbers. The cavity parameters such as cavity length and cavity width were compared with experimental data and agreed very closely. In order to reach in max cavity length in spite of divergency problems the iterative algorithm is introduced. This algorithm uses the high artificial vapor’s viscosity which after each converged solution the vapor viscosity is decreased until the desired cavity length obtained consequently. The use of this algorithm in compared with direct solution for high cavitation numbers has less iteration so the CPU time for convergence is less than direct solution. in this algorithm the high viscosity selected for vapor and then the iterations began after that the solution was converged the cavity length is longer than real cavity length compared to experimental data and the cavity width is thinner so the vapor’s viscosity decreased and the iteration is started based on pervious solution’s data therefore the cavity length is decreased. This procedure is applied continuously till the desired cavitation number and pressure flow field was reached .<\div>

۳Investigating the Capability of Potential Flow Theory for Modeling Planar Symmetric and
نویسنده(ها): ، ،
اطلاعات انتشار: دهمین همایش ملی صنایع دریایی ایران، سال
تعداد صفحات: ۱۱
Present paper's main aim is investigating the capability of potential flow theory for modeling supercavitating flow. Based on this theory , a numerical algorithm for capturing cavity boundary in two and three dimensional symmetric and axisymmetric flow is introduced . This numerical scheme is capable of capturing a surpecaity's boundary in vast range of cavitation numbers with high accuracy. Like the other similar studies on supercavitating flow employing idea flow theory, the length of the cavity is supposed to be known and the related cavitation number and cavity profile are the output of this scheme; but, the most novel distinctions between this study and other similar works is the numerical scheme employed for updating the cavity's boundary and the closure model which is applied for closing the cavity in down stream of the flow. After presentation of the numerical algorithm for both symmetric and axisymmetric flow, a comprehensive comparison between this scheme's result and the other similar numerical modeling of 2D symmetric and axisymmetric cavitating flow is accomplished. Juxtaposition of the obtained results and comparing them with experimental data indicates that there is a basic difference between essence of results accuracy in 2D and 3D cavitating flow modeling using ideal flow theory. Finally it was concluded that, although the 2D symmetric and axisymmetric cavitating flow have basic differences with each other but some relations and similarities could be observed in these flows<\div>
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