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Численное исследование задачи о раскрытии купола парашютатезисы доклада
- Автор: Джалалова М.В.
- Сборник: Материалы Международной конференции Нелинейные задачи теории гидродинамической устойчивости и турбулентность, 2014, панс.Звенигородский РАН
- Тезисы
- Год издания: 2014
- Место издания: НИИ механики МГУ
- Первая страница: 65
- Последняя страница: 68
- Аннотация: Для решения задачи о раскрытии купола парашюта предложен модифицированный лагранжевый подход, требующий существенно меньших вычислительных и временных ресурсов по сравнению с методом прямого компьютерного моделирования в потоке газа – Fluid Structure Interaction. One of the issues in the parachute industry, both in theory and in practice, remains the question of the parachute efficiency improvement as a braking device, i. e. the question of increasing the value of the drag coef-ficient Cp by introducing the additional constructive components. We investigate the effect of the pole vent and the existence of the central line on the drag coefficient value. The solution of this problem was performed by numerical simulation. Verification of the numerical proce-dure was carried out through the results of the experimental studies in the wind tunnel A-6 at the Institute of Me-chanics, Moscow State University. Several parachute models, representing a flat circle in the cutting area of 0.5 m2, made of nylon fabric with zero structural permeability at a flow rate V = 25 m/s, are considered. The number of suspension lines was n = 40 in both numerical and experimental models, the diameter of the pole vent was varied in the range of 70 mm to 140 mm, the central line length was equal to the length of the suspension lines – 800 mm. The drag coefficient Cp for the usual parachute with the same parameters but without central line and the pole vent was estimated separately. Currently the main way to solve the problem of the parachute canopy deployment is the method of the di-rect computer simulation in the gas stream – FSI approach (Fluid Structure Interaction), based on the combined Lagrangian-Eulerian description of the motion [3]. However, this approach requires significant computational resources and time, that is especially difficult for the optimization problems to which this task belongs. The conven-tional quasistatic Lagrangian approach (without interaction with the gas) does not work in this case, due to a lack of convergence of the computation procedure. The solution of such a problem was obtained in [2] with several sim-plifications. In this paper we propose a new, modified Lagrangian approach based on an iterative procedure consisting of two stages. At the first stage, the task of the parachute canopy deployment is solved step by step in a dynamic formulation using explicit time integration scheme with a prescribed pressure drop on the canopy, taken from the experiment [1]. Pressure value was specified as a linear function of time with a direction normal to the initial canopy configuration for the current step. The magnitude of the time interval between the steps was chosen from the procedure convergence requirement. At the final stage the problem has already solved with the quasistatic implicit time integration scheme with the canopy configuration resulting from the dynamic analysis. Convergence of the solution at this stage is reached in just few steps. Comparison of the results of the numerical simulation, using the proposed approach, with the experimental data shows a good agreement. As can be seen from the graph representing the values of the drag coefficient dependence Cp on the vent value F, the difference between the numerical and experimental data is less than 5%. A typical shape of the open parachute, obtained in the numerical calculations, is presented in the figure. REFERENCES 1. Kh.А. Rakhmatulin. Theory of Axisymmetric Parachutes. Parachutes and Permeable Objects. Moscow. Published in MSU, 1975, pp. 3-35. 2. Dzhalalova M.V., Leonov S.V. Effect of Structural Permeability on the Stability of a Parachute with Four Sus-pension Lines. Moscow Univrsity Mechanics Bulletin – Springer. 68, № 1, pp. 28-31. 3. S. Sathe, R. Benney, R. Charles, E. Doucette, J. Miletti, M. Senga, K. Stein and T.E. Tezduyar, "Fluid-Structure Interaction Modeling of Complex Parachute Designs with the Space-Time Finite Element Techniques", Computers & Fluids, 36 (2007) pp.127-135.
- Добавил в систему: Джалалова Маргарита Васильевна