List of aerospace subject articles

Open Access Article

1 - Novel Aspect of Composite Sandwich Fairing Structure Optimization of a Two Stages Launch Vehicle by Using MDO Independent Subspace Approach
Foozie Morovat Jafar Roshanian Ali Mozaffari Hadi Zaare

In this paper, a novel composite sandwich structure analysis of Launch Vehicle (LV) fairing is considered and proposed by a new Multidisciplinary Design Optimization (MDO) for a two-stage launch vehicle. Accordingly, “Multidisciplinary Design Optimization based on More

In this paper, a novel composite sandwich structure analysis of Launch Vehicle (LV) fairing is considered and proposed by a new Multidisciplinary Design Optimization (MDO) for a two-stage launch vehicle. Accordingly, “Multidisciplinary Design Optimization based on Independent Subspaces” (MDOIS) is employed using the “Fixed Point Iteration” (FPI) method to achieve the best convergence at system level (SL) to segregate the disciplines. Therefore, two proposed subspaces overcome difficulties of common mentioned MDO of LVs. Hence, the first subspace is a MDO which includes propulsion, aerodynamics, weight and trajectory disciplines and the second one, includes the novel composite fairing structure optimization as the other single discipline optimization that considered as a compact problem analytically and numerically and it is one of the novelties of this work. By considering variables as propulsion, trajectory and also composite sandwich fairing structure design regarding to the variables of designing and the performing optimization process, the fairing mass has been reduced more and considerable with respect to the common two stages LVs. In addition, due to the global optimization of LVs this weight reduction caused in reduction of the total gross weight of LVs. This system engineering proves the high sufficiency of MDO in complicated designing and it can be a roadmap for the future space vehicles designers especially who want to consider the composite structure optimization in LVs. Manuscript profile

Open Access Article

2 - Investigating Cooling Effect with Compound Angle on the Combustion Chamber Wall Temperature
Mohamad Reza Nazari Behrooz Shahriari Farhad Sebghatollahi

Increasing the temperature of the turbine entrance gases increases the efficiency of the gas turbine cycle. Under these conditions, the combustion chamber wall temperature also increases, while there is no high temperature resistance alloy fitted with air motors. Theref More

Increasing the temperature of the turbine entrance gases increases the efficiency of the gas turbine cycle. Under these conditions, the combustion chamber wall temperature also increases, while there is no high temperature resistance alloy fitted with air motors. Therefore, it is necessary to use cooling methods to reduce the wall temperature. In this study, the cooling effect with compound angles investigated on the combustion chamber wall temperature. The three-dimensional combustion chamber k-ɛ is modelled under the conditions of the input speed and the turbulence model in the ANSYS Fluent software. Inlet air is injected from the cooled holes to the mainstream with compound angle, where the cooling flow angle is constant with the 30° horizontally, and the lateral angle changes from Beta =0 up to Beta=60 degrees. The combustion chamber has two flat planes and two sloping plates, in which the arrangement of cooling holes is different. The results show that this method better distributes the cooling air on the wall surface and covers the space between the cooling holes, especially on flat plates. With this method, the number of cooling holes and the amount of air used to cooling can be reduced. Manuscript profile

Open Access Article

3 - Quick and Effective Modal and Flutter Analyses for Low Aspect Ratio Wings
Masoud Basiri Hamid Farrokhfal Masoud Mosayebi Reza Koohi

10.30495/admt.2021.1902247.1200

In the present work, an analytical study is proposed to investigate the flutter behavior of low-aspect-ratio wings in subsonic flow. An equivalent plate model is used for structural modelling of a semi-monocoque main wing, consisting of ribs, skins, and spars. Legendre More

In the present work, an analytical study is proposed to investigate the flutter behavior of low-aspect-ratio wings in subsonic flow. An equivalent plate model is used for structural modelling of a semi-monocoque main wing, consisting of ribs, skins, and spars. Legendre polynomials are used in the Rayleigh-Ritz method as trial functions, and the first-order shear deformation theory is utilized to formulate the structural deformation. Boundary conditions are enforced by applying proper artificial springs. A doublet point method is used to calculate the unsteady aerodynamic loads. Chordwise pressure coefficient distribution at the tip and root of a rectangular wing oscillating in pitching motion is calculated. Flutter analysis is performed using the k method. Instead of using the computationally expensive finite element method, the proposed approach is intended to achieve purposes of quick modelling and effective analysis in free vibration and flutter analyses of low-aspect-ratio wings for preliminary design applications. The effects of aspect ratio on the flutter behavior of wings in subsonic flow are investigated. The obtained results are validated with the results available in the literature. Manuscript profile

Open Access Article

4 - The Aerodynamic Effects of the Blade Lean on a High-Aspect-Ratio Transonic Axial Flow Rotor
Mansour Asghari Mohsen Agha Seyed Mirzabozorg Mahmood Adami

In this study, the effect of tangential blade lean on the aerodynamic characteristics of low-transonic, high-aspect-ratio axial flow compressor rotor has been investigated by using the computational fluid dynamics. The B-Spline curvature with four control points of 25%, More

In this study, the effect of tangential blade lean on the aerodynamic characteristics of low-transonic, high-aspect-ratio axial flow compressor rotor has been investigated by using the computational fluid dynamics. The B-Spline curvature with four control points of 25%, 50%, 75% and 100% of span have been used to define the blade stacking line. Various leaned rotors have been created by rotating the circumferential position of control points and they have been simulated by Computational Fluid Dynamics (CFD). At the best state, the leaned blade improves the adiabatic efficiency and total pressure ratio of compressor about 0.55% and 0.75%, respectively. The results show that, lean angle at 100% span has most effect in the peak adiabatic efficiency rather than lean angle at other control points. Also, the results indicate that, in low-transonic, high-aspect-ratio rotor blades, the tangential change of the stacking line only causes the reduction of secondary flow, while the previous studies on high-transonic low-aspect-ratio rotor blades, such as NASA Rotor 37 and NASA Rotor 67 revealed the movement of shock wave toward the downstream and the reduction of the secondary flow. Manuscript profile

Open Access Article

5 - Investigation of the Effect of V-Clamp Band Design Parameters on the Bending and Axial Stiffness of the Flanged Joints
SeyyedAbdolSajjad Borhani AliAkbar Lotfi neyestanak Ali davar

The main target of this paper is to obtain an optimum wedge angle for best static and dynamic performance of a V-shaped clamp band separation mechanism. For this purpose, by using the finite element method, the proper 3D model for V-clamp band mechanism has been modelle More

The main target of this paper is to obtain an optimum wedge angle for best static and dynamic performance of a V-shaped clamp band separation mechanism. For this purpose, by using the finite element method, the proper 3D model for V-clamp band mechanism has been modelled and analysed in Abaqus/Explicit solver. In order to study the effect of wedge angle on bending and axial stiffness of V-clamp joint, many quasi-static analyses with different wedge angles were accomplished so the relation between wedge angle and axial stiffness of V-clamp joint under symmetric bending loading is extracted. In the next step, dynamic analyses were accomplished so the relation between wedge angle and separation time (duration between trigging moment and the time of disconnecting between flanges and wedged clamps) is extracted. For verification, this project results have been compared with the results of other researches and good agreement is observed. The results show that the optimal wedge angle for obtaining maximum stiffness together with minimum spring back disconnection time for the V-clamp band mechanism is 20˚. Manuscript profile

Open Access Article

6 - Effect of Aerodynamic Blade Change of Two-Stage Axial Subsonic Turbine on Design Point
Mahmood Adami Behrooz Shahriari Ali Zamani Gharaghoushi

In this research for reducing the effect of losses and increasing the efficiency, the bowing in the rotor and stator blades is used. In one mode rotor blades are curved and in other one, stator blades are curved. The amount of rotor loss, due to changes in the thickness More

In this research for reducing the effect of losses and increasing the efficiency, the bowing in the rotor and stator blades is used. In one mode rotor blades are curved and in other one, stator blades are curved. The amount of rotor loss, due to changes in the thickness of the trailing edge and operating rotational speed, have been investigated. To confirm the accuracy of the results, a turbine stage whose experimental results are available is modeled and numerical results have been compared with experimental results that indicate acceptable compliance. The turbulence model k-w-SST is used to solve turbulent flow. The positive bowing, creates a pressure gradient from the two ends of the blade towards the center of the blade, which leads to the directing of the secondary flows toward the center of the blade. This reduces the losses in the two ends of the blade and increases the loss in the middle part of the blade. Increasing the thickness of the trailing edge, as well as increasing the turbine’s operating rotational speed, will increase the loss. The curved rotor increases the efficiency and mass flow and power by 0.4% and 0.5% and 0.8% respectively and the curved nozzle reduces the efficiency and power by 0.3% and 4.9% but increases the mass flow by 0.2%. It also increases the thickness of the trailing edge of the first rotor from 0.2mm to 0.9mm at 24000 rotational speed and increases the total loss by about 35%. Manuscript profile

List of articles (by subject) aerospace