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CONTENTS
Volume 9, Number 2, March 2022
 


Abstract
The paper investigates the process of pulsation of a spherical cavity (bubble) in a liquid under the influence of a source of ultrasonic vibrations. The process of pulsation of a cavitation pocket in liquid is investigated. The Kirkwood-Bethe model was used to describe the motion. A numerical solution algorithm based on the Runge-Kutta- Felberg method of 4-5th order with adaptive selection of the integration step has been developed and implemented. It was revealed that if the initial bubble radius exceeds a certain value, then the bubble will perform several pulsations until the moment of collapse. The same applies to the case of exceeding the amplitude of ultrasonic vibrations of a certain value. The proposed algorithm makes it possible to fully describe the process of cavitation pulsations, to carry out comprehensive parametric studies and to evaluate the influence of various process parameters on the intensity of cavitation.

Key Words
intensity of cavitation; Kirkwood-Bethe model; numerical algorithm; pulsations of a cavity; ultrasonic vibration

Address
Elena L. Kuznetsova: Department of Engineering Graphics, Moscow Aviation Institute (National Research University),
Moscow, Russia
Eduard I. Starovoitov: Department of Building Mechanics, Belarusian State University of Transport, Gomel, Republic of Belarus
Sergey Vakhneev: Department of Engineering Graphics, Moscow Aviation Institute (National Research University),
Moscow, Russia
Elena V. Kutina: Department of Advanced Materials and Technologies for Aerospace Applications, Moscow Aviation Institute (National Research University), Moscow, Russia

Abstract
In this paper, a novel morphing mechanism using a deployable scissor structure was proposed for a variable camber morphing wing. The mechanism was designed through the optimization process so that the rib can form the target airfoils with different cambers. Lastly, the morphing wing was manufactured and its performance was successfully evaluated. The mechanism of the morphing wing rib was realized by a set of deployable scissor structure that can form diverse curvatures. This characteristic of the structure allows the mechanism to vary the camber that refers to the airfoil's curvature. The mechanism is not restrictive in defining the target shapes, allowing various airfoils and overall morphing wing shape to be implemented.

Key Words
aircraft; morphing wing; optimization; variable compliant camber wing

Address
Yeeryung Choi: Department of Aerospace Engineering, Seoul National University, Seoul, 08826, South Korea
Gun Jin Yun: Institute of Advanced Aerospace Technology, Seoul National University, Seoul, 08826, South Korea

Abstract
Supersonic projectiles like rockets, missiles, or aircraft find various applications in the field of defense. The shape of the wings is mainly designed as wedge shape or delta wings for supersonic vehicles. The study of supersonic flows over the wedges and flat plate delta wings around the large scale of incidence angle is considered in the supersonic projectile. In the present paper, the prime attention is to study the pressure at the nose of the plane wedge over the various Mach number and the various angles of incidence. Ghosh piston theory is used to obtain the pressure distribution analytically, and the results are compared with CFD analysis results. Thewedge angle and Mach number are the parameters considered for the research work. The range of wedge angle is 50 to 250, and Mach number is 1.5 to 4.0 are considered for the current research work. The analytical results show excellent agreement with the CFD results. The results show that both the parameters wedge angle and Mach number are influential parameters to vary the static pressure. The static pressure increases with an increase in Mach number and wedge angle.

Key Words
CFD analysis; supersonic; wedge angle

Address
Javed S. Shaikh: Department of Applied Sciences and Humanities, MIT School of Engineering, MIT Art, Design and Technology University, Pune-412201, India
Krishna Kumar: Department of Applied Sciences and Humanities, MIT School of Engineering, MIT Art, Design and Technology University, Pune-412201, India
Khizar A. Pathan: Department of Mechanical Engineering, Trinity College of Engineering and Research, Pune-411048, India
Sher A. Khan: Department of Mechanical Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia

Abstract
The paper presents the surface-modified NACA 2412 airfoil performance with variable cavity characteristics such as size, shape and orientation, by numerically investigated with the pre-validation study. The study attempts to improve the airfoil aerodynamic performance at 30 m/s with a variable angle of attack (AOA) ranging from 0o to 20o under Reynolds number (Re) 4.4x105. Through passive surface control techniques, a boundary layer control strategy has been enhanced to improve flow performance. An intense background survey has been carried out over the modifier orientation, shape, and numbers to differentiate the sub-critical and post-critical flow regimes. The wallbounded flows along with its governing equations are investigated using Reynolds Average Navier Strokes (RANS) solver coupled with one-equational transport Spalart Allmaras model. It was observed that the aerodynamic efficiency of cavity airfoil had been improved by enhancing maximum lift to drag ratio ((l/d) max) with delayed flow separation by keeping the flow attached beyond 0.25C even at a higher angle of attack. Detailed investigation on the cavity distribution pattern reveals that cavity depth and width are essential in degrading the early flow separation characteristics. In this study, overall general performance comparison, all the cavity airfoil models have delayed stalling compared to the original airfoil.

Key Words
aerodynamic performance; cavity; CFD simulation; flow separation; surface modifier; surface roughness; variable orientation

Address
Samuel Merryisha: School of Aerospace Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal 14300, Pulau Pinang, Malaysia
Parvathy Rajendran: School of Aerospace Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal 14300, Pulau Pinang, Malaysia; Faculty of Engineering & Computing, First City University College, Bandar Utama, Petaling Jaya 47800, Selangor, Malaysia
Sher Afghan Khan: Department of Mechanical Engineering, Faculty of Engineering, International Islamic University,
Kuala Lumpur 53100, Selangor, Malaysia

Abstract
A Modified fuzzy mechanical control of large-scale multiple time delayed dynamic systems in states is considered in this paper. To do this, at the first level, a two-step strategy is proposed to divide a large system into several interconnected subsystems. And we focus on the damage propagation for aircraft structural analysis of composite materials. As a modified fuzzy control command, the next was received as feedback theory based on the energetic function and the LMI optimal stability criteria which allow researchers to solve this problem and have the whole system in asymptotically stability. And we focus on the results which shows the high effective by the proposed theory utilized for damage propagation for aircraft structural analysis of composite materials.

Key Words
aerospace vehicles; LMI; nonlinear systems; smart control; stability analysis

Address
C.C. Hung: Department of Mechanical Engineering, National Taiwan University, Taiwan; Faculty of National Hsin Hua Senior High School, Tainan, Taiwan
T. Nguyen: Ha Tinh University, Dai Nai Campus, No. 447, Street 26/3, Dai Nai Ward, Ha Tinh City, Vietnam


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