Jurij Sodja

Computational Fluid Dynamics Analysis of an Optimized Load-Distribution Propeller

B = number of propeller blades CD = drag coefficient CL = lift coefficient CP = power coefficient, P= n D CT = thrust coefficient, T= n D c = chord D = propeller diameter G = normalized circulation function GG = Goldstein’s normalized circulation function GP = Prandtl’s normalized circulation function J = advance ratio, v0=nD M = Mach number n = propeller revolutions per second, =2 P = power Q = torque R = propeller radius Re = Reynolds number RH = propeller hub radius R1 = wake radius r = radial coordinate S = propeller disk area, R T = thrust ua = axial induced velocity u = angular induced velocity v = resultant velocity v0 = advance velocity w = axial vortex displacement velocity y = nondimensional wall distance = angle of attack = blade pitch angle = circulation = drag-to-lift ratio = propeller efficiency = propeller blade pitch, v0t0 2 v0= 1 = wake pitch = speed ratio, v0= R 1 = wake speed ratio, v0 w = R1 = nondimensional radius, r=R 1 = nondimensional wake radius, r=R1 = fluid density = flow angle = propeller angular velocity

Design of Flexible Propellers with Optimized Load-Distribution Characteristics

The mathematical model and experimental verification of flexible propeller blades are presented in this paper. The propeller aerodynamics model is based on an extended blade-element momentum model, while the Euler–Bernoulli beam theory and Saint–Venant theory of torsion are used to account for bending and torsional deformations of the blades, respectively. The proposed blade-element momentum model extends the standard blade-element momentum theory with the aim of providing a quick and robust model of propeller action capable of treating high-aspect-ratio propeller blades with a blade axis of arbitrary geometry. Based on the proposed mathematical model, a static flexible propeller blade design procedure and its associated analysis algorithm are established. Dynamic aeroelastic phenomena like propeller flutter and divergence are not covered by the presented mathematical model, design, and analysis algorithm. Experimental validation was carried out with an objective of evaluating the performance of the devel...

Experimental Evaluation of the Morphing Leading Edge Concept

This article presents an experimental evaluation of a morphing leading edge demonstrator by investigating its morphed shape, the level of induced strains in the airfoil skin, the actuation force, and the morphing mechanism’s capability to lock and transfer the applied loads. In addition, a finite element model of the demonstrator is assembled comprising an elastic morphing skin and a kinematic morphing mechanism. The obtained results are used to assess whether the demonstrator performs according to the design objectives, such as the target shape, the character of the morphing deformation and the morphing mechanism locking, applied during the design process. The comparison between experimental and numerical results yielded a good agreement in terms of observed morphed shape and pertaining strains. The average difference in morphed shape was less than 0.08% chord at the maximum actuator extension. The observed difference in the respective strains was less than 400 micro-strains. A significant difference, up to 70%, was observed in the actuation force, which was attributed to the modelling assumptions and to the force measurement technique employed in the experiment. Nevertheless, both results show good qualitative agreement showing similar trends.

Optimization, Manufacturing and Testing of a Composite Wing with Maximized Tip Deflection

The directional properties of composite materials offer excellent potential for stiffness tailoring. An optimal design of a composite structure can hence be used to favourably tackle aeroelastic behaviour, for instance, to passively alleviate load or to induce favourable displacements so as to counter adverse effects such as divergence. This article presents the design, manufacture and testing of an aeroelastically tailored composite wing targeting maximum deformation. The wing was designed using an optimization process combining a stiffness-based continuous optimization, followed by a discrete stacking sequence optimization with blended laminates. The optimized design was manufactured using a carbon fibre pre-preg. The wing was then tested at subsonic speeds upto 60m/s and wing deformation, lift and root bending moment were measured. The results from the wind tunnel tests and the simulations used in the optimization show good correlation. The large tailoring potential attainable using a simple rectangular planform wing show promising prospects for planned future experiments, which target stronger aeroelastic tailoring with forward-swept wings.

Experimental investigation of an autonomous flap for load alleviation

This paper presents an experimental aeroservoelastic investigation of a novel load alleviation concept using trailing edge flaps. These flaps are autonomous units, which are self-powered and self-actuated, using trailing edge tabs, thereby demonstrating advantages in comparison with conventional flap systems in terms of wiring and structural integration. The flaps are free-floating and mass underbalanced, such that they may flutter at operation velocities unless suppressed by their own control system. This makes the system very responsive for turbulence and control action. In the wind tunnel campaign presented in this paper, the limit cycle behavior of autonomous, free-floating flaps was investigated. It has been shown that limit cycle oscillation can be reached either through structural limiters or by control actions of the trailing edge tabs. In the latter case, the amplitude of the limit cycle oscillation is adjustable to the required energy output. An energy balance of harvested power and power consumption for actuators and sensing system was made showing that the vibration energy of limit cycle oscillations can be used to keep the amplitude of the limit cycle constant, while the electric batteries that power the load alleviation system are being charged.

Aeroelastic Design of Propellers with Optimized Load-Distribution Characteristics

The mathematical model and experimental verification of deformable propeller blades are presented in this paper. The propeller aerodynamics model is based on an extended bladeelement momentum model while the Euler-Bernoulli beam theory and Saint-Venant theory of torsion are used to account for bending and torsional deformations of the blades, respectively. The proposed blade-element momentum model extends the standard bladeelement momentum theory with the aim of providing a quick and robust model of propeller action capable of treating high aspect-ratio propeller blades with a blade axis of arbitrary geometry. Based on the proposed mathematical model a propeller blade aeroelastic design procedure and its associated analysis algorithm are established. Experimental validation was carried out with an objective of evaluating the performance of the developed mathematical model and the design strategy. Both theoretical and experimental results are presented along with pertinent concluding remarks.

Experimental and Numerical Investigation of an Autonomous Flap for Load Alleviation

This paper presents the design, a numerical aeroservoelastic investigation, and an experimental proof of concept of an autonomous flap system. Autonomous flaps are load-alleviation devices, intende...