نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده ی مهندسی مکانیک، دانشگاه تربیت دبیر شهیدرجایی
2 دانشکده ی مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجایی
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In this study, to investigate the intensity of cavitation-induced erosion, the bubble behavior around the NACA0015 2D hydrofoil was simulated from the Eulerian-Lagrangian perspective. Macroscopic examination of the cavitation flow was determined by a homogeneous mixture model (Eulerian method) and the trajectory of bubble motion based on the applied forces using Newton's second law and the development of numerical code (Lagrange method). One way to reduce the computational cost of the Lagrangian perspective is to use the Discrete Phase Model (DPM). In this method, the fluid is considered as a continuous environment, while the discrete phase is solved by tracing a large number of particles in the calculated flow field. The behavior of the bubble arises from the pressure gradient caused by the flow. Bubble oscillations were obtained from the modified Rayleigh-Plesset-Keller-Herring equation. This equation considers the compressible behavior of the bubble as the bubble collapse velocity approaches the speed of sound as well as the slip velocity between the bubble and the moving liquid. To pair the obtained results and solve them, the fourth-order Runge-Kutta method with variable time step was used, which increased the data solution speed up to 10 times. From the Keller& Kolodner relationship, a pressure wave emitted from the collapse of a spherical bubble, and the model of Soyama et al., the total energy of the cavitation-induced shocks, which is the result of the accumulation of all the shocks on each other, is obtained. The actual effects of flow for cavitation inception and erosion were investigated. Different cavitation numbers were used for cavitation inception with different radii. The results showed that the nucleation process occured in the cavitation inception numbers and the cavitation inception for flow with larger nuclei was visible better. As the cavitation number decreases, the bubble growth rate increases and as the bubble radius increases, the erosion intensity increases. At high cavitation numbers, the bubble oscillates around its initial radius; however, at the lowest cavitation number in this article, the number , we see an increase of nearly times the radius compared to the original radius. The erosion power of bubbles with an initial radius of is approximately times that of the erosion power of bubbles with an initial radius of and about times that of the initial bubbles of . The probable site of erosion is at the end of cavity at the hydrofoil level. As the bubbles increase in size, the number of collapses and their strength increase, and the dispersion of the distribution at the hydrofoil surface increases. The results were compared with other published works and had acceptable accuracy.
کلیدواژهها [English]
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