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rotor-blades
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Optimum kinetic and gas hold up distribution study in an NDMA hydrogenation reactor
, Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 ; Kazemeini, M ; Sharif University of Technology
2008
Abstract
Unsymmetrical Dimethyl hydrazine (UDMH) is used as stabilizer, fuel promoter, chemical in photography, and liquid fuel for fighter jet engines. Catalytic liquid phase hydrogenation of nitrosodimethylamine (NDMA) is one of the most efficient methods for the production of UDMH. Hydrogenation of NDMA to UDMH using a commercial 5% Pd/C catalyst in aqueous solution of NDMA was studied under constant temperature at 40°-70°C, ≤ 15 bar, and NDMA concentrations of 40-70 wt %. The effects of temperature, pressure, and NDMA concentration on NDMA conversion and yield of UDMH product in presence of undesired Dimethylamine (DMA) were studied. At NDMA concentration of > 50 wt %, the UDMH yield was < 0.89,...
2-D Design and Optimization of Axial Flow Compressor Blade with 2-Objective Method
, M.Sc. Thesis Sharif University of Technology ; Hajilouy Benisi, Ali (Supervisor)
Abstract
Axial compressors are utilized to increase compressible flow pressure in an efficient manner where mass flow rate is high, such as aviation engines and power generation gas turbines. The flow is compressed within this machine through several stages. Each stage consists of a rotor blade row followed by a stator blade row. Energy transfer to the air is performed on the rotor by changing its velocity vector. Then, pressure is recovered from velocity by diffusion, meanwhile turning the flow direction through stator blades. These blades have been designed and optimized with various methods evolved with developing computational and manufacturing facilities. In this thesis the aerodynamic design of...
Vortex Shedding Control behind Helicopter Rotor Blades, using Thin Oscillating Plates- Application to Helicopter Noise Reduction
, M.Sc. Thesis Sharif University of Technology ; Javadi, Khodayar (Supervisor)
Abstract
The interaction of the vortices and helicopter’s blades is the most significant source of generating the main rotor’s noise, especially in landing and rising. The kind of this noise is broadband and it is produced because of establishing the vortices behind the forward blade, their interaction with backward blade, changing their structures and creating turbulency loading. The known method for modeling of the interaction of the vortices structures and solid surfaces is the simple compounding the rod and airfoil. In this project, by using this method, the noise of the interaction of vortex and blade is modeled in the Reynolds number of 48000 with LES and FW-H Analogy as a hibrid method in...
A novel method to detect rotor blades echo
, Article IEEE National Radar Conference - Proceedings, 10 May 2010 through 14 May 2010, Washington DC ; 2010 , Pages 1331-1334 ; 10975659 (ISSN) ; 9781424458127 (ISBN) ; Nayebi, M. M ; Sharif University of Technology
2010
Abstract
In this paper, the effect of the main rotor of an armed helicopter on radar return signal and its modulation condition are considered. After analyzing references and experimental data, this paper proposes a new method based on inherent modulation in main rotor echo. This method is able to enhance the probability of detection. The simulation is performed for both simulated and practical echo signal. Simulation results confirm that our proposed scheme is effective. Moreover, a new domain for distinguishing and measuring the rotation feature of a rotary target is proposed. This paper is based on practical experiments (rotation domain)
Aeroelastic analysis of helicopter rotor blade in hover using an efficient reduced-order aerodynamic model
, Article Journal of Fluids and Structures ; Volume 25, Issue 8 , 2009 , Pages 1243-1257 ; 08899746 (ISSN) ; Salehzadeh Noubari, A ; Behbahani Nejad, M ; Haddadpour, H ; Sharif University of Technology
2009
Abstract
This paper presents a coupled flap-lag-torsion aeroelastic stability analysis and response of a hingeless helicopter blade in the hovering flight condition. The boundary element method based on the wake eigenvalues is used for the prediction of unsteady airloads of the rotor blade. The aeroelastic equations of motion of the rotor blade are derived by Galerkin's method. To obtain the aeroelastic stability and response, the governing nonlinear equations of motion are linearized about the nonlinear steady equilibrium positions using small perturbation theory. The equilibrium deflections are calculated through the iterative Newton-Raphson method. Numerical results comprising steady equilibrium...