Abstract
The primary goal of this research is to investigate flow separation phenomena using various turbulence
models. Also investigated are the effects of free-stream turbulence intensity on the flow over a NACA 0018 airfoil.
The flow field around a NACA 0018 airfoil has been numerically simulated using RANS at Reynolds numbers
ranging from 100,000 to 200,000 and angles of attack (AoA) ranging from 0o to 18o with various inflow conditions.
A parametric study is conducted over a range of chord Reynolds numbers for free-stream turbulence intensities from
0.1 % to 0.5 % to understand the effects of each parameter on the suction side laminar separation bubble. The results
showed that increasing the free-stream turbulence intensity reduces the length of the separation bubble formed over
the suction side of the airfoil, as well as the flow prediction accuracy of each model. These models were used to
compare the modeling accuracy and processing time improvements. The K- SST performs well in this simulation for estimating lift coefficients, with only small deviations at larger angles of attack. However, a stall was not predicted by the transition k-kl-omega. When predicting the location of flow reattachment over the airfoil, the transition k-klomega model also made some over-predictions. The Cp plots showed that the model generated results more in line with the experimental findings.
Address
Musavir Bashir, Parvathy Rajendran, Ambareen Khan: School of Aerospace Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, Pulau Pinang, Malaysia
Vijayanandh Raja: Department of Aeronautical Engineering, Kumaraguru College of Technology, Coimbatore-641049, Tamil Nadu, India
Sher Afghan Khan: Department of Mechanical Engineering, Faculty of Engineering, International Islamic University,
Kuala Lumpur 53100, Selangor, Malaysia
Abstract
This paper presents a basic methodology and a set of numerical tools for the preliminary design of solidfueled
ramjet missiles. An elementary code determines the baseline system configuration comprised of warhead, guidance-control, and propulsion masses and geometries from specific correlations found in the literature. Then, the system is refined with the help of external and internal ballistics codes. Equations of motion are solved for the flight's ascending, cruising, and descending stages and the internal ballistic set of equations designs the ramjet engine based
on liquefying fuels. The combined tools sized the booster and the ramjet sustainer engines for a long-range missile,
intended to transport 200 kg of payload for more than 300 km range flying near 14,000 m altitude at Mach 3.0. The
refined system configuration had 600 mm in diameter and 8,500 mm in length with overall mass of 2,128 kg and 890
kg/m3 density. Ramjet engine propellant mass fraction was estimated as 74%. Increased missile range can be attained
with paraffin-polyethylene blend burning at near constant regression rate through primary air mass flow rate control
and lateral 2-D air intakes.
Address
Rogério L.V. Cruz, Carlos A.G. Veras: Mechanical Engineering Department, University of Brasília, Campus Darcy Ribeiro, 910-900 Brasilia-DF, Brazil
Olexiy Shynkarenko: Department of Aerospace Engineering, University of Brasília, Gama Leste, 72444-240 Brasilia-DF, Brazil
Abstract
In this study, The Von Mises stresses in composite plate loaded in tension and repaired by a boron/epoxy scarf patch were analyzed using the finite element method. The performance of the repairs depends on several parameters: the dimensions and the intrinsic properties of the patch and the adhesive which are dependent on each other. Therefore, the method of experiment designs is used to determine the interaction effect of different parameters (patch folds), their optimum and the most influential parameter. The optimum of stacking sequences allows reducing stresses significantly, and thus permits designers to improve the quality of repairs.
Key Words
adhesive; optimization; repair; scarf patch; stacking sequence
Address
Salma Aminallah, Sidi Mohamed Fekih and Abdelrahmen Sahli: LMPM, Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89, Cité Ben M'hidi, 22000 Sidi Bel Abbes, Algeria
Abstract
In the first part of this study, a numerical simulation model was developed using the mechanical APDL software to validate the results of the 3D-elastisity theory on the laminated sandwich plate developed by Panago. The numerical simulation model showed a good agreement to the results of Pagano's theory in terms of deflection, normal stresses, and shear stresses. In the second part of this study, the developed numerical simulation model was used to define different plates dimensions and fibers layup orientations to examine the load response in terms of deflection and stresses. Further analysis was implemented on the natural frequencies of laminated xxx plates of the plates. The layup configurations include Unidirectional (UD), Cross-Ply (CP), Quasi-Isotropic (QI), the linear bio-inspired known as Linear-Helicoidal (LH), and the nonlinear bio-inspired known as Fibonacci-Helicoidal (FH). The following numerical simulation model can be used for the design and study of novel, sophisticated bio-inspired composite structures in a variety of configurations subjected to sinusoidal or constant loads.
Key Words
bending and vibration; bio-inspired structures; composite materials; finite elements analysis; shell structure
Address
Faisal Baakeel, Mohamed A. Eltaher, Muhammad Adnan Basha,
Ammar Melibari: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia
Alaa A. Abdelrhman: Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, Zagazig, Egypt
Abstract
In our research we have offered a solid solution for aeronautical analysis. which can guarantee the asymptotic stability of coupled nonlinear facilities. According to the theoretical solutions and methods presented, the engine of this aircraft is a small high-bypass turbofan engine. using the non-linear aero-motor control approach and this paper focuses on the power management function of the aero-motor control system. These include static controls and transient controls. A mathematical model of the high-bypass-ratio two-spool unmixed-flow aeroengine was developed through a set of nonlinear dynamic equations verified by experimental data. A single actuator using the displacement method is designed to maintain a certain level of thrust under steady-state conditions. and maintains repeatable performance during transient operation from the requested thrust phase to the next. A single controller can compensate for the effects of noise and harmonic noise at many performance points. And the dynamic performance of a single controller is satisfactory during the transient. for fairness Numerical and computer experiments are described in the perfection of the methods we offer in research.
Key Words
aviation vehicles; inequality controlling & nonlinear stability analysis; linear matrix; spacecraft
Address
C.C. Hung: Faculty of National Hsin Hua Senior High School, Tainan, Taiwan
T. Nguyen: Ha Tinh University, Dai Nai Ward, Ha Tinh City, Vietnam
open access