Rasul Niazmand Bilandi - Academia.edu (original) (raw)
Papers by Rasul Niazmand Bilandi
Journal of Marine Science and Engineering, 2020
Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts... more Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.
Procedia Manufacturing , 2020
Laboratory measurements are performed to find the performance in calm water of a planing hull wit... more Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by... more In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in order to compare the different hull configurations. It should also be noted that the mathematical model has been developed in such a way that it has the potential to model the sweep-back step and transverse the vertical motions of single-stepped planing hulls in future studies.
Journal of Marine Science and Engineering, 2020
Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts... more Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.
Procedia Manufacturing , 2020
Laboratory measurements are performed to find the performance in calm water of a planing hull wit... more Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by... more In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in order to compare the different hull configurations. It should also be noted that the mathematical model has been developed in such a way that it has the potential to model the sweep-back step and transverse the vertical motions of single-stepped planing hulls in future studies.