Modern approach towards unsteady & steady aerodynamics

Karpagam institute of technology, S.PANDIYARAJAN,

INTRODUCTION

The goal this PPT is to develop a versatile formulae to compute the unsteady lift and thrust forces generated by unsteady flapping airfoil.

We consider both plunging and pitching types of motion and develop a time marching simulation based on early work in unsteady aerodynamics. Finally applied to take off problems of micro UAV.

MOTIVATION&PERSPECTIVE

Lift and propulsion through why flapping has long been a compelling subject , as the primary mode of flight propulsion in the animals.

Theories as to how a typical lifting surface can be oscillated to produce both lift & thrust have their foundations in unsteady aerodynamics , whose lift development began in the 20’s, such that ornithopters.

BACK GROUND OF UNSTEADYAERODYNAMICS

Evolution of field of unsteady aerodynamics

Foundation Advent of computerApplications

FOUNDATIONS

WANGER - Distribution of vorticity in the wake of airfoil undergoing unsteady motionVON KARMAN- He uses Kelvin circulation theory’s a wake of integral approach to lift and thrust develop of flapping airfoil. THEODORSEN - he approched the problems potentail flow theory and solely concerned lift and applied to problem of flutter.GARRICK - he gave a more detailed way to calculate the thrust given by VON KARMAN by combining them with the work of THEODORSEN.

ADVENT OF COMPUTER

PLATZER – panel method to compute unsteady lift & thrust forces for pitch & plunge motion of one or two animals.HALL& HALL - addressed the issue of minimum power flapping flight & compute the optimal Flapping frequency by using a vortex – lattice model of the wake. HUGO -used an unsteady lifting line theory , based on theodeson results to compute forces & control the unsteady lift occurring in gusty condition. It not allows computation of thrust forces.McCUNE- aside from being computation of thrust force.

UNSTEADY FLOW DEFINATION & EQUATIONS

Average thrust coefficient

Non dimensional time

Pitching reduced frequency

Plugging reduced frequency

UNSTEADY FLOW DEFINATION & EQUATIONS

Vertical Downwash

Quasi- steady forcecoefficient

Inertial forcecoefficient

UNSTEADY FLOW DEFINATION &EQUATIONS

Wake induced forcecoefficient

Suction force coefficient

FOR UNSTEADY LIFT CALCULATION GRAPH

VALIDATIONS

VALIDATIONS

FOA UNSTEADY THRUST CALCULATION GRAPH

APPLICATION

MICRO UNMANNED AIR VECHILE

Uninhabited aerial vehicle with dimensions similar to that of a small bird.Flapping is more easily mechanized in small vehicles due to scaling laws .For instance it is much easier to make a structure that will support the forces associated with high frequency flapping if the wing is small.In addition, micro machined devices , smart materials & advanced composites all represent a new technology that could make flapping flight more feasible mechanically a small system.

Until now, the study of birds in flight has been particularly challenging for researchers since their mobile subjects tend to fly away. However, information on all aspects of high-altitude migratory flight can now finally be obtained at the Advanced Facility for Avian Research (AFAR)

AFAR wing tunnel

CONCLUTION

This PPT has presented compute the lift and thrust producing by the flapping wings.In the formulae based on unsteady aerodynamics and compute the forces successfully.Only applicable for micro UAV mechanism. Our future thought is apply to big aircraft

THANK YOU

“Avian wing kinematics therefore appear to have been tuned by natural selection for high aerodynamic efficiency”.