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Ice protection systemsTeam 3Amjad KhanDinesh BalurajKarthikeyan BaskaranMurali KrishnaSafiq AhmadVarun PrakashOverviewTypes of ice on AircraftsClear ice: Forms in temp. range between 0C to -10C It is a homogeneous and transparent ice coating ; difficult to breakRime iceForms between -15C to-20C Rough milky white appearance and a comb-like appearanceMixed ice/ Conglomerated ice:It is a combination of Clear and Rime ice Forms between -10C to -15C.Frost ice It is the result of water freezing on unprotected surfaces, often forming behind deicing boots or heated leading edges.

Types of ice on Aircrafts (contd.)

Ice protectionIce formation on aircrafts can lead to catastrophic failuresIce protection is necessary to maintain smooth flightIce protection can be done by Anti-icing Preventing ice formation/growthDeicing Removal of iceFunction of both is to protect the aircraft from ice growth and effects of it on the flight. Effect of Icing:Structural icing can block the pitot tube and static ports and cause the breakage of antennas on the aircraft.

Aerodynamic effects. Ice can alter the shape of an aerofoil.This can cause control problems, change the angle of attack at which the aircraft stalls,Weight penalty (control and altitude problem)

Uncontrolled roll phenomenon referred to as roll upset that is associated with severe in-flight icing.

Tail plane (empennage) stallControl buffetingPilot induced oscillation

Effect of icing on Aircraft

Pneumatic Deicing SystemPneumatic Boot Deicing SystemBasic Principle-Alternate or simultaneous inflations and deflations of the boot breaks the accreted ice into particles

Aerodynamic and Centrifugal forces on rotating aerofoils removes the ice

Deicing system

Boot thickness < 0.075 inchPneumatic Boots

ComponentsSpan wise / Chord wise pneumatic tubes

Regulated pressure source, Vacuum source and air distribution system (Primary components)

Air filters, Control switches, relief valves (Miscellaneous)

Turbine Powered Pneumatic Boot Deicing system

Reciprocating Engine Powered Pneumatic Boot Deicing System

Pneumatic Impulse Deicing System

Deicer EmbodimentsSchematics and Working

Electro Impulsive Deicing SystemElectro impulse deicing systemElectro-Impulse De-icing (EIDI) is classified as a mechanical ice protection method

Ice is shattered, debonded, and expelled from a surface by a hammer-like blow delivered electro dynamically.

Removal of the ice shard is aided by turbulent airflow; thus, relatively low electrical energy is required.

EIDI Operating conceptPrimarily, this system consists of of ribbon-wire coils rigidly supported inside the aircraft surface to be de-iced

It separated from small air gap and the coil under the skin induces the strong eddy currents on surface

The circuit must have low resistance and inductance to permit the discharge to be very rapid, typically less than one-half millisecond in duration EIDI Operating concept(contd)The eddy current and coil current fields are mutually repulsive, resulting in a toroidal-shaped pressure on the skin opposite the coil

The peak force on the skin is typically 400-500 pounds, produces sound resembling on metal

Resulting acceleration sheds ice from the surface and can shed ice as thin as 0.05 but acceleration is rapidEIDI Operating concept(contd.)

Impulse coils in a leading edgeEIDI Operating concept(contd.)During EIDI systems operations, a coil receives two or three successive pulses from the capacitor unit

The span wise extent of wing leading edge that each coil (or coil pair) will deice depends largely on the structural properties of the leading edge

The capacitor is then switched to another coil station, and then to another until it cycles around the aircraft

The time to complete the de-icing cycle must be less than the time for acceptable ice accretion for the protected surfacesEIDI Design conceptThe EIDI system requires a careful and rather sophisticated design

The current pulse width in the coil resulting from the capacitor discharge must be properly matched to the skin electrical properties and to the leading-edge structural dynamic response

Failure to do this properly severely reduces the coils ice expelling performance

Installation of the power supply and control system in the aircraft should be done in a manner that minimizes the distance through which the high-energy electrical pulse must travelEIDI Design concept(contd.)

Applications of EIDIIt is used in the following parts,Aerofoil and leading edges Engine inlets Propellers and nose conesHelicopter rotors and hubsRadomes and AntennasMiscellaneous intakes and ventsComparison Through this method deicing of wind shield and engine components cannot be done.

Sensors are not applicable in this method.

Capacitors are used since the coil produces the current which is drive through the these capacitors.

It can be easily shed ice as thin as 0.05

AdvantagesWeight comparable to other deicing systems.

Nonintrusive in the airstream, hence no aerodynamic penalty.

Ice of all types is expelled, with only light residual ice remaining after the impulses (i.e.) reliable deicing.

Low power required. EIDI system power consumption is less than 1 percent of that required for hot air or electro thermal anti-ice systems.Limitations It has limited use.

It is not an anti-icing system, so some ice will be present over most of the aircraft leading edges during flight in icing.

Complex design requirements.

Outside the aircraft the discharges may be quite loud, resembling a light gunshot.Eddy Current Deicing SystemEddy Current Deicing System (ECDS)ECDS is classified under the electro-mechanical ice protection system.Uses eddy currents to produce momentary displacement of surface.The mechanism of ice removal is similar to earlier mentioned electro impulsive systems.This deicing system is differs in the design that causes the outer surface to accelerate.

ECDS Operating PrincipleAccreted ice expulsed from the blanket protected structures by a strong, rapid outward thrust of blanket surface.

The rapid outward thrust is the reaction to pulsed current passed through flattened planar coils.

These planar coils run span-wise along the LE as shown.

ECDS Operating Principle contd.

ECDS - ComponentsECDS in Smaller Aircrafts

The power supply housing all the capacitor charging and distributionECDS in Larger Aircrafts

ECDS Design criterionsEg. Of Elastomeric : NeopreneHard fasteners in regions of glue bond line for peeling strength39ECDS Potential ApplicationsECDS can be used on:Wing leading edgeEngine inlet periphery

Its usage is limited in:WindshieldsRadar and antennasFlight sensors

Windshields not optically clearRadar eddy current setup covers radars and antennas Flight sensors sensitive , hence thermal 40ECDS A SummarySonic Pulse Electro - Expulsive Deicing SystemIntroductionThe system was developed in collaboration with NASA Lewis and ARPAs SBIR program.The Sonic Pulse Electro-Expulsive Deicer (SPEED) is an acceleration based deicer for aircraft ice protection.SPEED evolved from the Electro-Impulsive deicing (EIDI) concept with a major improvement in the actuator coil and electronics.Fatalities by accident categories, fatal accidents, worldwide commercial jet fleet.

Old methods could not remove thick ice formation over the leading edge.

An example: ATR-72 accident, Rose lawn, Indiana, Oct.31,1994, all passengers (72) killed . Embraer 120, Monroe, Michigan, Jan.9, 1997, 29 passengers & crew members killed.

Sonic pulse Electro expulsive deicing system consists of : Deicing Control Unit (DCU):smart box controller an Energy Storage Bank contains:Capacitorsthe electromagnetic actuatorssensor.

Sonic Pulse Electro Expulsive Deicing System

MechanismMounted on the substructure of the leading edge.

It apply impulsive loads directly to the aircraft skin or outer surface material.

The rapid acceleration debonds and sheds ice into the airstream in a very efficient manner (ice layers can be shed as thin as 12 mm).

Icing Onset Sensor (IOS) can be added to the basic system to provide an autonomous mode of operation

ActuatorTypical sketch of the Sonic Pulse Electro Expulsive Deicing System by Innovative Dynamics. ProcessVarious uses in aircrafts:Propeller leading edgeHelicopter rotor bladeWing leading edgeTail leading edge

Also used in military applications

SPEED vs. Pneumatic Deicing boots. ParameterModern Technology: SPEEDTraditional Technology: Pneumatic bootsSurface life

Drag increment

Cost

Weight

Electric power from 12m span

Life of aircraft

No increase

Equivalent

Equivalent

0.7kwMonths rather not yearsdepending on service

Measurable increase

Baseline

Baseline

Zero Merits Electrically operatedVery low power consumptionErosion resistantReliable and maintenance-freeFault-tolerant operation Graceful degradation (of aircraft performance)Superior PerformanceCompetitively PricedEnhanced Maintainability

Maintenance and cost:Maintenance:No periodic inspection requiredLife time- 15 yearsCapacitors must be replaced that it reaches 1 million cyclesCuffs have been tested at over 250,000 firings and have not failed.

Cost:10m wing span Aircraft about 50,000$-75,000$System power requirements 300-700w RMS.Power consumption is about 450w for an entire aircraft for one pulse.

Ultrasonic Deicing SystemPrincipleThe ultrasonic de-icing system creates transverse shear stresses at the ice/aerofoil interface that exceed the ice adhesion strength of ice, promoting delamination of ice.

It is done by launching ultrasonic shear-horizontal waves at the ice-substrate interface.

The goal is to induce sufficiently large shear strains at the ice-substrate interface so as to weaken or break the interfacial bond.

To demonstrate instantaneous ice delamination due to ultrasonic excitation, a suitable actuator, able to provide transverse shear stresses exceeding the adhesion strength of ice to steel, has to be selected.Deicing Mechanism

Deicing Mechanism (contd.)Design RequirementsPower consumption of less than 2 kW with minimal current consumption.

Produce a shear stress of 1.42MPa at the ice Aluminium interface

Withstand centrifugal forces due to blade rotation

Withstand ambient temperatures from -50C to 100C

Not disturb the blade aerodynamics56Overview of Available Actuators

Piezo Electric ActuatorThe direct piezoelectric effect is the property of piezoelectric crystals to produce a charge when stressed Inverse piezoelectric effect is the ability of piezoelectric crystals to strain under an applied electric field. Thus piezoelectric materials can be used as electro-mechanical actuators and sensors.The goal of the actuator is to launch guided shear horizontal waves through the rotor blade erosion shield (substrate) so as to overcome the adhesive strength of the ice-substrate bond.Have the capability of producing the required maximum stresses

Available in various sizes and shapes as well as various modes of vibration (thickness extension, length extension and thickness shear)

Consume low electrical power compared to thermal heating systems as well as other electro-mechanical actuation technologies

Can produce bi-directional strainPiezo Electric Actuator (contd.)SMA Ice deicing systemSHAPE MEMORY ALLOY DE-ICING TECHNOLOGYShape Memory Alloys can be plastically deformed at some relatively low temperature (Martensite phase)Upon exposure to some higher temperature (Austenite phase), will return to their original shape.Advantage:Low size & weightLess energy consumptionResistance to corrosion, abrasion

One Way SMA in Leading EdgeTypes:One Way SMA (Cannot return unassisted)Two Way SMA (Use Temperature to return to original form)

Actuation methods:Self actuation using latent heat of fusion, increase surface temperature by 25 FExternal resistance heating system

NiTi is used:highly durable 4% elastic deformationMemory strain 8%Permanent deformation > 5% after million cycle

Debonding Action0.1-0.3% shear strain sufficient to debond ice deposits

Once ice removed, SMA is cooled by ambient air

Span wise PositioningChord wise PositioningPositioning Shape Memory Alloy in the Leading edge

Block Diagram of Current Pulse generatorBlock Diagram of Active State SheetSummaryIce protection and types of ice encountered in an aircraft

Ice protection system namely:Pneumatic deicing Electro-impulsive deicingEddy current deicingSonic pulsed electro expulsive deicingUltrasonic deicing SMA technologies for deicing

Except pneumatic, the above listed are still in need of complete approval from FAA for commercial use.

Questions