Ravikumar M.L.
(Photo to be added)
Design Engineer, Infotech
Enterprises
M.Tech Industrial Training
Project (2005):
“Flutter
characteristics of aircraft wings and aero engine blade”
A structure with
non-circular cross section experiences a fluid force that changes with
orientation to the flow. As the structure vibrates, its orientation changes and
the fluid flow oscillates if the oscillating fluid force tends to increase
vibration, the structure is aerodynamically unstable and very large-amplitude
vibration can result. Flutter is the term applied to a class of aero elastic
phenomenon of aircraft structure.
Flutter can be defined as the dynamic
instability of an elastic body in an air-stream. It is most commonly encountered
on the bodies subjected to large latest aerodynamic loads of the lift type,
such as aircraft wings, tails and control surfaces.
An airplane wing, as an elastic body, has infinitely many
degrees of freedom. But owing to its particular construction, its elastic
deformation in chord wise section can usually be described with sufficient
accuracy by two quantities: the deflection at a reference point, and the angle
of rotation about that point, i.e., the flexural and torsional deformations,
respectively. Similarly, for a control surface, such as a flap or an aileron,
its freedom to turn about the hinge line is so much more important than its
elastic deformation, that ordinarily it is possible to describe the deflection
of a control surface simply by angle of rotation about its hinge line. In
general, then, it is sufficient to consider three variables in wing flutter:
the flexure, the torsion, and the control-surface rotation. A flutter mode
consisting of all the three element is called ternary flutter. In special
cases, however, two of the variables predominate, and the corresponding flutter
modes are called binary flutter modes. Similar consideration applies to
airplane tail surfaces.
Blade failures due to fatigue are predominantly
vibration related. When a rotor blade passes across the nozzle of the stator,
it experiences fluctuating lift and moment forces repeatedly at a frequency
given by the number of nozzles multiplied by the speed of a machine. The blades
are very flexible members, in the sense that a significant number of their
natural frequencies can be in the region of possible nozzle excitation
frequencies. It experiences resonance several times during the starting and
shutting of the machine, i.e. whenever the instantaneous speed of machine gives
rise to nozzle excitation coinciding with the blade frequencies. This is termed
as Blade Flutter in an aero engine turbine.
Flutter phenomenon is crucial to the
design of airborne vehicles. it is an aircraft performance parameter. Because
of this aircraft is going to loose its stability, failure of wings, stiffness
of the structure goes down, failure of blades in turbine engine and finally it
leads to loss of an aircraft.
Flutter can be reduced by following methods:
1. Shrouded Blade Design: By providing extrusions on both sides of
a blade such that when it rotates, each side of extrusions comes in contact
with the adjacent blades there by providing no vibration. The shrouds also
serve to cut down gas leakage around the tips of the turbine blades.
2.
Increasing Damping characteristics: Any vibrating structure possesses a certain capacity to
dissipate energy, which may be made up of several damping mechanisms. The
damping in a turbine blade comes essentially from three different sources i.e. Material
damping, Friction damping and Gas damping.
3.
By taking following measures to secure
stability in the design of a structure:
·
Provide
sufficient stiffness, so that critical speed of aero elastic instabilities is
inherently high.
·
Furnish
good aerodynamic design, so that the flow remains un-separated in service
conditions.
·
Break
the inertia and aerodynamic couplings,
·
Provide
a servomechanism to control the phase relation ship between various components
of motion.
Typical Results of the Eigen-value
analysis of the blade:
Material of Blade: Titanium super alloy (Ti-64)
Education:
·
M.Tech.
in Machine Design at B.M.S. College of Engineering,
·
Bachelor
of Engineering (Mechanical) Completed in Dec 2001 from P.E.S. Institute of
Technology, Bangalore from Bangalore University with Aggregate 77.63%.
Computer Skills:
Platforms : Windows
2000, NT.
Languages: FORTRAN, C, and XML.
Solid Modeling: CATIA, V5-R11/R14, Solid
Works 2005
FEM Analysis: Ansys 5.4
Work Experience:
1
Presently
working as a Design Engineer at Infotech Enterprises Bangalore.
2
Worked
as a CAD Engineer at Geometric software
solution Ltd.,
3
Worked
as a Contract Engineer at GTRE
4
Worked
as a Graduate trainee at Bharath
Electronics,
Personal:
Father’s
Name: B. Mari Swamy; Languages known: English,
Hindi and Kannada;
Hobbies: Traveling, Cricket, chess, Internet,
Contact Details:
Address: S/O B.MARI SWAMY, No.300, C.A.R.POLICE
QUARTERS, M.S.B.LANE,
Phone:
91 80 26701900; Mobile: 98454 21740
Email ID: ml_ravi3@rediffmail.com;
ravikumarml@infotechsw.com
| Appointment | Research Interests | Publications
| Positions Held | Academic
Experience | Students | Citations | Courses |
| My Alma Matter | My Teachers | My Friends | My Colleagues | My Family | My Relatives |