Sharif Digital Repository

Purpose of this thesis is to discover the governing equation of Flying Wing aircrafts. In Flying Wing aircrafts crew, payload, fuel, and equipment are typically housed inside the main wing structure. A clean flying wing is sometimes presented as theoretically the most aerodynamically efficient (lowest drag) design configuration for a fixed wing aircraft. We assume Flying wing as plate. Achieve structural formulation needs to use modal deflections and put them in Lagrangian equations. In the right had side, pressure on flying wing can be found. To obtain air pressure on flying wing in this thesis, applying Quasi steady aerodynamic and Howe distribution is necessary. Applying this method on ... 

Dynamical behavior of a dragonfly-like with rigid flapping wings considering aerodynamic forces has been modelled and simulated. At first, the dragonfly with its unique flying capabilities and the reasons for choosing it has been introduced. Then, modelling process is started with preliminary definitions including frames, coordinates and equations of motion, continued by applying initial conditions and ended with verification tests. After that, aerodynamic effects in a quasi-steady sense is added to dynamical model resulting in an 18 DOF model developed to be used for nonlinear simulation or controller designing. At the end, the results are validated in comparison to an experimental study.... 

In recent years, requirement to increase projectile performance, leads to a great interest in high angle of attack Aerodynamics. Projectile Maneuverability is a concept which is defined by having the capability to perform at high angles of attack while maintaining attached flow over the tail, rather than a capability of performing a mission in minimum possible duration. Interaction between body, wing and tail vortices can delay vortex breakdown over the wing and as a result may enhance projectile maneuverability. Studies show that wing aspect ratio and tail location have a remarkable influence on the vortices interaction and thus projectile maneuverability. In the present study, a series of... 

Control surfaces are used in combat aircrafts to control the pitching moment and to help the aircraft perform high angle of attack manoeuvres. For delta wing configuration, the flow characteristics around the horizontal tail depend on the wing and tail flow field and their interactions. The flow over delta wing is mainly characterised by strong vortices. These vortices move downstream and affect the tail flow field making the problem more complicated. The goal of this research is to study the effect of tail up wash on the horizontal wing-body- tail configurations in subsonic flow. For this purpose a series of wind tunnel tests were conducted on a model containing a moveable horizontal tail... 

In this thesis the behavior of a 3D wing has investigated by Flow visualization and pressure acquisition test. The goal of this tests was considering changes in 3D wing section parameter in comparison with 2D airfoils. The performed Tests showed that variation in 3D wing treatment is affected by finite aspect ratio and sweep angle and also indicate changes in pressure profile, increasing pressure peak and decreasing effective speed. CFD studies has conducted to investigate special effect of sweep angle and show that lift and drag coefficient decrease with increasing sweep angle. Also different section pressure profile near the wing tip and intersection of wing/fuselage varies and miss... 

Swept wings are of great interest for achieving high speed as well as increasing the critical Mach number in aircrafts and unmanned flying vehicles. The governing fluid mechanical phenomenon on swept wings is strongly influenced by the chordwise and spanwise components of the cross-flow. Laminar airfoils are employed for drag reduction and postponing the boundary layer transition from laminar to turbulence. Hence, the knowledge about the boundary layer structure and instability modes is of great significance. A series of wind tunnel tests are performed to examine the flow field over a swept wing at various conditions. The wing has a laminar flow airfoil section similar to NACA 6-series ones.... 

The delta wing has proven to be very useful for the study and understanding of the basic features of separation-induced vortex flows since many aspects of these vortex flows can be generated with this simple shape. A phenomenon of special importance to vortical flows is vortex breakdown. Vortex breakdown remains an important and complicated phenomenon that can have negative or positive effects. The delta wing leading edge vortex is emphases in many experiments. Most of these experiments are focused on the delta wing only.In this research, emphasis is on vortex interaction of delta wing-canard-fuselage configuration. A series of low speed wind tunnel tests were carried out to investigate... 

In the present work the stability analysis for the coupled aeroelasticity and fuel sloshing in supersonic wings is represented. The wing and store structure is modeled using the finite element method. The supersonic wing aerodynamic is modeled by the linear piston theory and store aerodynamic is modeled by the semi-stable slender body piston theory. Fuel sloshing in the store with desired geometry is modeled by the boundary element method. The coupled structure, aerodynamic and sloshing governing equations are drawn by using the Galerkin method and reduce order modeling teqnique for them and an effective numerical model was developed that is capable to analyze the stability for... 

In this study some experiments were performed to investigate the effect of sweep angle on the transition location of laminar flow to turbulent flow. Three half wing models were used, each having a different sweep angle but with the same aspect ratio in various angles of attack. Two flat plates were used at the ends of the swept wing models to prevent the flow from rolling up over the wing. By simulating flow over infinity swept wing by eliminating tip vertices, the effect of sweep angle on flow transition phenomenon was investigated.
The experiments included the study of transition flow via hot-film sensors, which were glued on the wing surface. We found that the small leading-edge... 

Application of canard next to the wing have been widely used in military industry for decades. Although it’s most application is in supersonic flying objects, It has to do it’s duty in lower air speeds too. The aim of this study was to investigate the influence on the wing due to the presence of canard in supersonic flow regime. But because of the importance of the issue, significant attempts has been conducted in subsonic flow regime. High research volume, Absence of a comprehensive theory in this branch and the local defense industry demand as a developing country on the other hand, delivers the importance and applicability of the subject. Another issue of importance is that the... 

In this study, adaptive control of attitude and position of a rigid body insect-like flapping wing is investigated. For this purpose, a non-linear dynamic and time varying modeling and simulation is carried out initially with six degrees of freedom, and then the accuracy of the simulation is evaluated during different test cases. In order to design the controller, non-linear and time varying dynamic is transformed into non-linear and time-invariant dynamic using theory of averaging. Then, a non-linear controller is designed based on Lyapunov stability theory. Due to the inefficiency of the aforementioned controller under disturbances and unknown uncertainties in the model, an adaptive... 

Wind tunnel experiments are conducted to evaluate surface pressure distribution over a semi span swept wing with sweep angle of 33 degrees. The wing section has a laminar flow airfoil similar to that of NACA 6-series airfoils. The tests were conducted at speeds ranging from 50 to 70m/s with and without surface roughness. Surface static pressure was measured on the wing upper surface at three different chordwise rows located at the inboard station, (section 1, 2y/b=0.2), middle station, (section 2, 2y/b=0.43), and outboard station, (section 3, 2y/b=0.78). The differences between pressure distributions on the three sections of the wing were studied and the experimental results showed that...