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Looking to upgrade your Fuel Flow Management system? We are now offering a
Fuel Flow trade-in program.Read
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Shadin Avionics Fuel Flow Transducers
The
transducer is a device that converts the mechanical motion of a spinning turbine
into an electronic signal that is read by the fuel computer. The magnetic
pick-up assembly detects the spinning turbine and counts the revolutions. This
produces a series of pulses that is transmitted to the fuel computer. The
computer uses the pulse frequency to calculate the fuel flow over time. The
Shadin Avionics Company Incorporated-designed fuel flow transducer can be used
in conjunction with all of our fuel totalizer units and fuel/airdata
computers.
Shadin Avionics offers two types of fuel flow transducers that
cover almost all General aviation and warbird aircraft. (Please refer to the
installation STC approval list.)
* Tangential flow transducers --
designed for reciprocating engines with low system pressure (up to 200psi) and
fuel flow rates (up to 45gph). They require a stainless steel flame shield,
sleeve, canister or box.
* Axial flow transducers -- designed for turbine
and large radial engines with high system pressure (up to 2000psi) and fuel flow
(up to 450gph) applications. These transducers are made of stainless steel and
meet all FAA requirements for installation in the engine compartment without
additional heat or flame shielding. These transducers have excellent linearity
and immunity from viscosity variation due to fuel temperature variation and low
locked rotor pressure drop.
All hardware used in these assemblies, as
well as the bracket to support them, is approved by the FAA under the PMA
system.
General Description:
When the axially moving fluid hits the side of
the stationary turbine blade it gets turned in a spiral motion and the fluid
emerges from the turbine with a tangential velocity component. The reaction of
this fluid on each turbine blade is a tangential force producing torque to turn
the turbine in the opposite direction of the deflected flow.
For a given
fuel flow the turbine will accelerate until it reaches such a rotational speed
as to cause the fluid to meet the turbine blade point on. Under this condition,
the fluid will cease to accelerate the turbine which will maintain a constant
speed.
For a certain turbine the blade angle sets proportionality between
axial flow velocity (flow) and tangential blade velocity (rotational speed) at
which the turbine rotation will stabilize.
With the magnetic pick-up
assembly detecting the turbine blade motion a pulse output at a frequency
proportional to turbine speed will be produced.
Thus the pulse frequency
produced by the turbine flow transducer is proportional to the flow rate. It is
then used with electronic devices to calculate and display flow rates as well as
flow volume over a period of time.
Effect of Friction:
The most significant friction effect is due to
liquid viscosity. Both bearing friction and pick-up magnetic drag are
comparatively small and are covered by calibration test runs.
Viscous
friction tends to lower the rotational speed and hence the flow K-Factor,
especially at low flow and high viscosity conditions.
The frequency of
pulse rates generated at different flows ideally follows a straight line.
Viscous friction causes deviation at low flow as shown.
The flow K-Factor
plotted against the output pulse frequency divided by the kinematic viscosity
(i.e. H/) gives the viscous performance curve, which will be fixed for a
specific turbine regardless of what liquid was used.
The viscous
performance curve is divided into three regions:
* Viscous: The flow
through turbine blades is laminar. The deviation of
K-Factor from its
ideal value is inversely proportional to H/.
* Transient: The flow
through turbine blades turns turbulent. K-Factor changes to its value for
turbulent flow.
* Turbulent: The flow through turbine blades is fully
turbulent. K-Factor tends to be constant or slowly approaches the ideal value,
depending on the smoothness of the flow passages.
Material
Selection:
All the body components, including the flow straighteners and
ball bearings, are made out of 303 stainless steel which has no magnetic
properties but is ideal as far as the yield stress, high melting point and
resistance to corrosion.
The turbine is made of a magnetic stainless
material (14 pH) with a medium permeability number to facilitate disturbing the
magnetic field.
The electronics body is made of carbon steel to act as a
shield from any external magnetic field generated by the aircraft electrical
systems.
Shadin Transducer Part Number Chart
|
Part Number |
Flow Range
(GPH) |
K-Factor
(PPG) |
Pressure
Drop
(PSI) |
Rotor Locked at
(GPH) |
Flare Fittings |
|
660526 |
7-70 |
42 |
6.0 Jet A-1
5.0 AvGas |
70 |
-8 |
|
660526A |
7-70 |
42 |
6.0 Jet A-1
5.0 AvGas |
70 |
-8 |
|
660527 |
45-450 |
5.8 |
6.2 Jet A-1 |
450 |
-10 |
|
660532 |
10-200 |
9.6 |
3.5 Jet A-1 |
200 |
-10 |
|
660534 |
10-160 |
20 |
6.5 Jet A-1
5.5 AvGas |
160 |
-8 |
|
660535 |
7.5-100 |
24 |
5.0 Jet A-1
4.3 AvGas |
100 |
-10 |
|
660537 |
15-350 |
7.8 |
6.0 Jet A-1
5.3 AvGas |
350 |
-10 |
|
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| Other Fuel Management Products |
DIGIFLO-L |
MINIFLO-L |
DIGIDATA |
MICROFLO-L |
|