Flutter is a phenomenon resulting from the interaction between aerodynamic and structural dynamic forces and may lead to a destructive instability. The aerodynamic forces on an oscillating airfoil combination of two independent degrees of freedom have been determined. The problem resolves itself into the solution of certain definite integrals, which have been identified as Theodorsen functions. The theory, being based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing-ection theory relating to the steady case. The mechanism of aerodynamic instability has been analyzed in detail. An exact solution, involving potential flow and the adoption of the Kutta condition, has been analyzed in detail. The solution is of a simple form and
is expressed by means of an auxiliary parameter K. The use of finite element modeling technique and unsteady aerodynamic modeling with the V-G method for flutter speed prediction was used on a fixed rectangular and tapered wing to determine the flutter speed boundaries. To build the wing the Ansys 5.4 program was used and the extract values were substituted in the Matlab program which is designed to determine the flutter speed and then predicted the various effects on flutter speed. The program gave us approximately identical results to the results of the referred researches. The following wing design parameters were investigated skin shell thickness, material properties, cross section area for beams, and changing altitude. Results of these calculations indicate that structural mode shape variation plays a significant role in the determination of wing flutter boundary.
The methodology of the concept of sovereignty in contemporary Islamic thought
Rotating blades are the important parts in gas turbines. Hence, an accurate mathematical estimation (F.E.M) of the stresses and deformations characteristics was required in the design applications to avoid failure. In recent year’s there are researchers interest in the effect of temperature on solid bodies has greatly increased, The main of this study investigated the thermal and rotational effects. So, the thermal stresses due to high pressure and temperature are studies, also determine the steady state stresses and deformations of rotating blades due to mechanical effect. Many parameters such as thickness and centre of rotating are investigated in this paper. The
... Show MoreThe city of Baghdad underwent various changes and developments, which significantly influenced its urban character. And other urban fabric. The most prominent changes in the architecture of that period characterized by the emergence and spread of modern architecture, it represents the period between the 1940s and the late seventies of the twentieth century, which had its many reasons and various factors that paved and supported, and even encouraged the spread of modern architecture of the world, The advanced world in the adoption of a global architecture spread in the city of Baghdad by a number of international architects and Iraqis, who came from those countries and saturation ideas
... Show MoreReuse of spent hydrodesulphurization (HDS) of middle petroleum fractions catalyst CoMo/γAl2O3 was accomplished via removal of coke and contaminants such as vanadium, Iron, Nickel, and sulfur. Three processes were adopted; extraction, leaching, decoking. Soluble and insoluble coke was removed. Leaching step used three different solvents (oxalic acid, ammonium peroxydisulfate and oxalic acid + H2O2) in separate in order to remove contaminant metals (V, S, Ni and Fe).
The effect of soluble coke removal on leaching step was studied. It was found that the removal of soluble coke significantly enhances the leaching of contaminants and barely affected the removal of active metals
... Show MoreImplementations of Transition Metal complexes of shiff Base Derived Ampyrone
This paper deals with a dilapidated urban part with a proposal to renew it and return it to the life cycle of the city, as in the neighborhood of Al-Mdawar, adjacent to the port of Beirut. It discusses the challenges and the need for renewal, the causes of urban deterioration, the urban development approach and the history of the regulations applied to Beirut, In the studied area. It also proposes solutions to improve its lifestyle based on urban planning tools and design to achieve people's aspirations, preserve identity and rearrange its integration with the Beirut central district area.
