The document discusses vortex flow sensors used in automobiles. It describes how vortex flow sensors measure the quantity of air entering an internal combustion engine by detecting the Karman vortex frequency created by air flowing past a bluff object, allowing the engine control unit to calculate fuel injection. The frequency of the vortices is proportional to flow velocity. Vortex flow sensors provide a digital flow signal with benefits like low cost, reliability, and linear output, but work only within a particular velocity range.

1. Vortex Flow / Turbine
Fluid Sensor
-Pankaj Kumar (201179)
-Mayur Patil (201178)
Automobile Engineering

3. Use in Automobile
• Measure quantity of air going into IC engine.
• Electronically controlled engines (ECU)
• Petrol- Calculates Fuel injection in carburetor
• Diesel- Calculates Fuel injection in cylinder ports

4. Principle of Operation
The analogy of a golf ball moving through the air is useful
in describing vortex formation:
A slow moving putt barely displaces
the molecules of air
The higher velocity of a chip shot
causes irregular eddies to form behind
the ball
The velocity associated with a drive is
sufficient to cause a strong, regular
vortex formation behind the ball

5. Principle of Operation
Light breeze - Laminar flow,
no vortices formed
NR = 0-5000
Stiff breeze - Transition flow,
irregular vortex formation
NR = 5000-20000
Strong wind - Turbulent flow,
regular vortex pattern
NR = >20000

6. Principle of Operation
When a flowing medium strikes a non-streamlined bluff object,
it separates, moves around the object and passes downstream.
At the point of contact with the object, vortex swirls separate from the
body on alternating sides. This separation causes a local increase
in pressure and a decrease in velocity on one side and a decrease
in pressure and an increase in velocity on the opposite side. The
alternating velocities generate alternating pressure forces on either side
of the bluff body. The frequency of these pressure changes is
proportional to velocity.
l

7. Principle of Operation
The Karman vortex frequency “f” is proportional to the velocity ”v”.
Therefore, it is possible to obtain the flow rate by measuring the Karman
vortex frequency:
f = St (v/d)
where: f = Karman vortex frequency
St = Strouhal number (constant)
v = Velocity
d = Width of vortex shedder (constant)

8. Vortex Flow meter Benefits
• Digital flow signal
– No zero drift
– Pulse output for totalizing
• Low installed cost
• Reliability
• Wide range ability
• Inherently Linear output
• Low pressure drop
• Liquid, steam, or gas applications
• Immune to density & viscosity changes

9. Vortex Flow meter Limitations
• Works over a particular velocity range.
• Requires specialization for different fluid flow
measurement

10. References
• Wikipedia
http://en.wikipedia.org/wiki/Air_flow_meter
• Yokogawa Corporation of America