Hekmat Alighanbari

Hekmat Alighanbari
Ryerson University · Department of Aerospace Engineering

Professor

About

47
Publications
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814
Citations

Publications

Publications (47)
Article
Tilting ducted fans attached to the wing tips of vertical take-off and landing unmanned aerial vehicles define new applications for these types of aerial vehicles. This new configuration gives vertical take-off and landing unmanned aerial vehicles the ability to hover like helicopters and fly forward like airplanes, which results in using any arbit...
Article
Tilting ducted fans mounted at the wing tips of vertical take-off and landing unmanned aerial vehicles define new applications for these types of aerial vehicles. This new configuration gives vertical take-off and landing unmanned aerial vehicles the ability to hover like helicopters and fly forward like airplanes, which results in using any arbitr...
Article
Reaction wheels, as one of the most commonly used actuators in satellite attitude control systems, are prone to malfunction which could lead to catastrophic failures. Such malfunctions can be detected and addressed in time if proper analytical redundancy algorithms such as parameter estimation and control reconfiguration are employed. Major challen...
Article
Unsteady aerodynamics and specifically the dynamic stall phenomenon significantly affect the aerodynamic performance of the wind turbine blades. This paper presents a 2D computational investigation on the aerodynamic characteristics of three specific airfoils for small horizontal axis wind turbines subjected to unsteady viscous flow. The unsteady i...
Article
Aircraft wing geometry morphing is a technology that has seen recent interest due to demand for aircraft to improve aerodynamic performance for fuel saving. One proposed idea to alter wing geometry is by a modular morphing wing designed through a discretization method and constructed using variable geometry truss mechanisms (VGTM). For each morphin...
Conference Paper
This paper presents use of evolutionary algorithms for Rotary Inverted Pendulum (RIP) controller. The goal is to balance the pendulum in the inverted position. The intuition of this work is in using state feedback controller as the stabilizer component of the controller and also pole selection of the statefeedback controller based on evolutionary o...
Conference Paper
This paper presents particle swarm optimization approach for designing Rotary Inverted Pendulum (RIP) controller. The goal is to balance the pendulum in the inverted position. The intuition of this work is using state-feedback controller as the stabilizer component of the system whereas in other existing systems, only Proportional-Integral-Derivati...
Article
The unsteady low Reynolds number aerodynamics phenomena around flapping wings are addressed in several investigations. Elsewhere, airfoils at higher Mach numbers and Reynolds numbers have been treated quite comprehensively in the literature. It is duly noted that the influence of heat transfer phenomena on the aerodynamic performance of flapping wi...
Article
A new method for solving an optimal control problem using a particle swarm optimization (PSO) method and avoiding the calculations needed in the common analytical approaches is proposed. PSO mimics the unpredictable motion of a group of birds while searching for food, trying to take advantage of the information sharing mechanism that affects the ov...
Article
Complex viscous mechanisms such as leading edge vortices play a dominant role in the generation of instantaneous force and moment in low Reynolds number flows. The dependence of the corresponding fluid flow characteristics on the governing flow and system parameters in unsteady motions, e.g. plunging, adds to the inherent complexity of the problem....
Conference Paper
Fault diagnosis, identification and isolation (FDI) is an important field of research due to its advantages for the cost efficiency of the product development, maintenance and its lifetime. Unscented Kalman Filter (UKF) is one of the well-known apparatus for this purpose. In this paper UKF is used to estimate the wheel speed and current of the Reac...
Article
The unsteady aerodynamics of a pair of multi-plunging airfoils is studied using computational fluid dynamics based on a finite volume method and dynamic layering mesh motion algorithm. The two-dimensional unsteady, incompressible Navier-Stokes equations are used as the governing equations while the thin ellipsoidal airfoils, commonly used in micro...
Article
The flow field of a flapping airfoil in Low Reynolds Number (LRN) flow regime is associated with complex nonlinear vortex shedding and viscous phenomena. The respective fluid dynamics of such a flow is investigated here through Computational Fluid Dynamics (CFD) based on the Finite Volume Method (FVM). The governing equations are the unsteady, inco...
Book
Full-text available
Experimental, analytical and numerical studies are performed to investigate the details and characteristics of swirling submerged jets when transferred into a system of helical vortices downstream in a bathtub-like flow. Dye-injection is used to visualize the transformation process of a swirling submerged jet into a tank filled with the same statio...
Conference Paper
The objective of the present study is to simulate the low Reynolds number (LRN) aerodynamics of a pair of two-dimensional elliptic airfoils performing plunging motion. To this end, the influence of Reynolds number (Re) and frequency of oscillations on the fluid flow is investigated. Navier-Stokes (N-S) equations with Finite Volume Method (FVM) are...
Conference Paper
The focus of the present study is to develop an Artificial Neural Network (ANN) model to predict the unsteady lift coefficients of an ellipsoidal airfoil in Low-Reynolds-Number (LRN) flapping motion. Computational Fluid Dynamics (CFD) simulations of the flow around the airfoil flapping in the form of a novel figure-eight pattern are conducted. The...
Article
The growing applications of low Reynolds number (LRN) operating vehicles impose the need for accurate LRN flow solutions. These applications usually involve complex unsteady phenomena, which depend on the kinematics of the vehicle such as pitching, plunging, and flapping of a wing. The objective of the present study is to address the issues related...
Conference Paper
Full-text available
A number of experimental measurements are carried out to study the unsteady wake of a pitching Eppler-361 airfoil. The flow field in the wake was measured by a hot-wire anemometry at the downstream distance from trailing edge of 0.25 chord. All data were taken at the mean angle of attack of 2.5 deg and the reduced frequency of 0.1. The amplitude of...
Conference Paper
A computational fluid dynamics study is conducted to examine the aerodynamic behavior of a low Reynolds number plunging airfoil. The influence of Reynolds number (Re) and Strouhal number (St) on the fluid flow is investigated. In this study, incompressible Navier-Stokes (N-S) equations are solved using a Finite Volume Method (FVM). The instantaneou...
Conference Paper
The objective of the present study is to simulate the low Reynolds number (LRN) fluid dynamics of a two-dimensional (2-D) elliptic airfoil performing a novel figure-eight-like motion. To this end, the influence of Reynolds number (Re) and amplitude of pitching motion on the fluid flow is investigated. Navier-Stokes (N-S) equations are solved using...
Conference Paper
The objective of the present study is to investigate the low Reynolds number (LRN) fluid dynamics of an elliptic airfoil performing a novel figure-eight-like motion. To this mean, the influence of phase angle between the pitching and translational (heaving and lagging) motions and the amplitude of translational motions on the fluid flow is simulate...
Conference Paper
Full-text available
The present study is conducted to investigate the details and characteristics of swirling submerged jets when transferred into a system of helical vortices downstream in a bathtub-like flow. Both analytical and numerical results are presented. In the analytical solution, upstream flow is considered to be two-dimensional with piecewise-constant vort...
Conference Paper
The objective of the present study is to develop an Adaptive Network-based Fuzzy Inference System (ANFIS) model to predict the unsteady lift coefficients of an airfoil. The airfoil performs a flapping motion in Low-Reynolds-Number (LRN) flow regime. Computational Fluid Dynamics (CFD) simulations of the flow field are conducted and the corresponding...
Conference Paper
The objective of the present study is to investigate the effects of the reduced frequency on the aerodynamic characteristics of a three dimensional pitching blade. Experimental data are recorded at three sections of the blade model; tip, middle, and root sections at low and high turbulence intensities. A 2D numerical simulation is also conducted ba...
Conference Paper
The objective of the present study is to investigate the low Reynolds number (LRN) fluid dynamics of two airfoils in pitching oscillations. The airfoils are in a tandem configuration and perform in-phase oscillations. Navier-Stokes (NS) equations with Finite Volume Method (FVM) are used and the instantaneous aerodynamic force coefficients are analy...
Conference Paper
An experimental investigation is conducted to examine the effects of the amplitude of pitching oscillations and mean angle of attack on the aerodynamic behavior of a three-dimensional pitching blade. A 2D numerical simulation is also conducted based on the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations and Finite Volume Method (FVM) and...
Article
Computational fluid dynamics (CFD) simulations of an airfoil performing a figure-eight-like kinematics is conducted in low Reynolds number (LRN) flow regime. Finite volume method (FVM) is used to discretize the governing two-dimensional (2-D) Navier-Stokes (N-S) equations. The flow field and vortical patterns around the airfoil are examined in deta...
Article
The free vibration of piecewise uniform defective laminated composite beams is investigated. The governing differential equations of motion are coupled both in torsional and bending deformations. A Dynamic Finite Cracked Element (DFCE) is developed and is applied to slender beams, characterized by an offset between inertial and bending axes. The hy...
Conference Paper
The objective of the present study is to investigate low Reynolds number aerodynamics of a harmonically pitching NACA0012 airfoil. To this mean, the influence of some unsteady parameters; amplitude of oscillation, d, reduced frequency, k, and Reynolds number, Re, on the aerodynamic performance of the airfoil is investigated. Computational Fluid Dyn...
Conference Paper
A Dynamic Stiffness Matrix (DSM) is developed to analyse the free vibration characteristics of cracked, thick, laminated, unidirectional, unbalanced composite beams. Based on the closed form solution of the governing differential equations, an existing 'exact' DSM formulation for bending-torsion vibration of an intact composite beam is first briefl...
Article
Full-text available
An airfoil subjected to two-dimensional incompressible inviscid flow is considered. The airfoil is supported via a translational and a torsional springs. The aeroelastic integro-differential equations of motion for the airfoil are reformulated into a system of six first-order autonomous ordinary differential equations. These are the simplest and l...
Conference Paper
A Dynamic Finite Cracked Element is developed for the free vibration analysis of a uniform laminated unidirectional unbalanced composite beam. The local flexibility of a through thickness static cracked beam is developed based on stress intensity factors that have been corrected for geometry and material anisotropy. Dynamic Trigonometric Shape Func...
Article
The present study develops a model to correlate the self-excited panel motion with the cyclic elastoplastic behaviour of the material causing fatigue failure. The analysis takes into account the elastic and plastic responses of materials to estimate the fatigue life of the panels subjected to limit-cycle oscillations (LCO). A damage-dynamics analys...
Article
A signal processing technique is presented to analyze nonlinear aeroelastic time series where limit-cycle oscillations and chaotic motions may occur. A powerful method to study nonlinear aeroelastic behavior of aircraft structures is the phase-space reconstruction technique. In the reconstruction process, the mutual information function and the per...
Article
Aeroelastic behavior of airfoil-aileron combination with freeplay structural nonlinearity in aileron hinge moment was analyzed. The airfoil's dynamical behavior and possibility of nonperiodic motions were investigated using both a finite difference method and dual-input describing function technique. Bifurcation analysis of the system indicated var...
Conference Paper
The objective of the present work is detail bifurcation analysis of an airfoil subjected to two-dimensional incompressible inviscid flow taking into account a cubic structural nonlinearity in the pitch direction. The integro-differential aeroelastic equations of motion for the airfoil are reformulated into a system of six first-order autonomous ord...
Article
In this paper, the destabilization due to small damping of the follower force system, known as Beck's problem, and of the cantilevered pipe conveying fluid system, two nonconservative systems, is considered. Instead of looking for a mathematical explanation, e.g., the evolution of the eigenvalues with different parameters, a more "physical" explana...
Conference Paper
In this paper, the destabilization due to small damping of the follower force system, known as Beck’s problem, and of the pipe conveying fluid system, two nonconservative systems, is considered. Instead of looking for a mathematical explanation, e.g. the evolution of the eigenvalues with different parameters, a more ‘physical’ explanation is provid...
Article
A bifurcation analysis of a two-dimensional airfoil with a structural nonlinearity in the pitch direction and subject to incompressible flow is presented. The nonlinearity is an analytical third-order rational curve fitted to a structural freeplay. The aeroelastic equations-of-motion are reformulated into a system of eight first-order ordinary diff...
Article
A two-dimensional airfoil with either a bilinear or cubic structural nonlinearity in pitch, and subject to incompressible flow has been analysed; the aerodynamic forces on the airfoil are evaluated using Wagner's function. The resulting equations are either integrated numerically using a finite difference method to give time histories of the airfoi...
Article
A two-dimensional airfoil with a free-play nonlinearity in pitch subject to incompressible flow has been analyzed. The aerodynamic forces on the airfoil were evaluated using Wagner's function and the resulting equations integrated numerically to give time histories of the airfoil motion. Regions of limit cycle oscillation are detected for velocitie...
Article
The Dynamic Finite Element (DFE) approach in vibration analysis of different beam configuration is well established. The DFE method can be presented as an intermediate method between the classical Finite Element Method (FEM) and the Dynamic Stiffness Matrix (DSM) formulation. The aim of this investigation is to extend the DFE methodology to the vib...