Ice Protection

Team – 3 Amjad Khan

Dinesh Baluraj Karthikeyan Baskaran

Murali Krishna Safiq Ahmad

Varun Prakash

Overview

Introduction Ice protection Types of ice protection

systems

Pneumatic deicing system

Electro-impulsive

deicing system

Eddy current deicing system

SPEED Ultrasonic

deicing system

SMA technologies for deicing

Summary

Types of ice on Aircrafts Clear ice:

Forms in temp. range between 0˚C to -10˚C

It is a homogeneous and transparent ice coating ; difficult to break

When the droplet size is large its known as “Super-cooled Large Droplet” (SLD).

Rime ice

Forms between -15˚C to-20˚C

Rough milky white appearance and a comb-like appearance

Mixed ice/ Conglomerated ice:

It is a combination of Clear and Rime ice

Forms between -10˚C to -15˚C.

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 protection Ice formation on aircrafts can lead to catastrophic

failures

The consequences of neglecting ice formation are: Loss of Lift

Increased drag due flow separation

Unresponsive control surfaces

All the above lead to loss of control of the aircraft

Ice protection can be done by Anti-icing – Preventing ice formation/growth

Deicing – Removal of ice

Effect of icing on Aircraft

Pneumatic Deicing System

Pneumatic Boot Deicing System Basic Principle-Alternate or simultaneous inflations and

deflations of the boot breaks the accreted ice into particles

Aerodynamic and Centrifugal forces on rotating airfoils removes the ice

Deicing system

Boot thickness < 0.075 inch

Pneumatic Boots

Components Span 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

• Repair, Inspection, Maintenance are well understood

• Simplest and cost effective method

Advantages

• Boot material deteriorates with time

• If accretion of ice is too thin, bridging may be formed

Disadvantages

Pneumatic Impulse Deicing System

Deicer Embodiments

Configuration of Deicer

Skin-Bonded

Recess-Bonded

Integrated Composite

Leading Edge Assembly

Modular Composite

Leading Edge Assembly

Schematics and Working

• Low power requirement

• Aerodynamically non-intrusive and No runback and refreezing

• Thin ice removing capability (0.08-0.2 inch)

Advantages

• Mechanical system-residual ice remains after the cycle

• Noise

• Fatigue of deicer Disadvantages

Electro – Impulsive Deicing System

Electro – impulse deicing system

Electro-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 concept

Primarily, 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(cont’d)

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 rapid

EIDI – Operating concept(contd.)

Impulse coils in a leading edge

EIDI – 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 surfaces

EIDI – Design concept

The 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 coil’s 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 travel

EIDI – Design concept(contd.)

Applications of EIDI

It is used in the following parts,

Airfoil and leading edges

Engine inlets

Propellers and nose cones

Helicopter rotors and hubs

Radomes and Antennas

Miscellaneous intakes and vents

Comparison

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

Advantages

Weight 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 electrothermal 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 System

Eddy 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 and electro – expulsive systems.

This deicing system is differs in the design that causes the outer surface to accelerate.

ECDS – Operating Principle

Accreted 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 - Components

ECDS in Smaller Aircrafts

The power supply housing all the

capacitor charging and distribution

ECDS in Larger Aircrafts

ECDS – Design criterions D

eice

r B

lan

ket

Material

Metallic

Good erosion characteristics

Ease of maintenance

Elastomeric Easier to install

(retro-fit)

Installation

Retro-fitting

Flexible adhesives

Hard fasteners

ECDS – Potential Applications

ECDS can be used on:

Wing leading edge

Engine inlet periphery

Its usage is limited in:

Windshields

Radar and antennas

Flight sensors

ECDS – A Summary

Advantages Limitations

Sonic Pulse Electro - Expulsive Deicing System

Introduction

The system was developed in collaboration with NASA

Lewis and ARPA’s 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 :

1. Deicing Control Unit (DCU):

a. smart box controller

2. an Energy Storage Bank contains:

a. Capacitors

b. the electromagnetic actuators

c. sensor.

Sonic Pulse Electro Expulsive Deicing System

Mechanism Mounted 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

Actuator

Typical sketch of the Sonic Pulse Electro Expulsive Deicing System by Innovative Dynamics.

. • IOS detects and monitors

. • Sensor commands the deicer to fire

. • Feedback if another cycle required or not

.

• Smart box controller identifies the electrical leaks and short circuit

Process

Various uses in aircrafts:

Propeller leading edge

Helicopter rotor blade

Wing leading edge

Tail leading edge

Also used in military applications

SPEED vs. Pneumatic Deicing boots. Parameter Modern Technology:

SPEED Traditional Technology: Pneumatic boots

1. Surface life

2. Drag increment

3. Cost

4. Weight

5. Electric power from 12m span

Life of aircraft No increase Equivalent Equivalent 0.7kw

Months rather not years depending on service Measurable increase Baseline Baseline Zero

Merits

Electrically operated

Very low power consumption

Erosion resistant

Reliable and maintenance-free

Fault-tolerant operation

Graceful degradation (of aircraft performance)

Superior Performance

Competitively Priced

Enhanced Maintainability

Maintenance and cost: Maintenance: No periodic inspection required Life time- 15 years Capacitors must be replaced that it reaches 1 million cycles Cuffs 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 System

Principle

The ultrasonic de-icing system creates transverse shear stresses at the ice/airfoil 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

Target adhesive shear strength of the ice aluminum interface bond

dynamic shear stress generated by the actuator at the interface increases the stress concentration

stress concentrations result in crack patterns

The mechanical, dielectric and piezoelectric losses in the actuator combined with the mechanical losses in the ice layer are converted into heat energy

Deicing Mechanism (contd.)

Design Requirements Power consumption of less than 2 kW with minimal current

consumption.

Produce a shear stress of 1.42MPa at the ice – Aluminum interface

Withstand centrifugal forces due to blade rotation

Withstand ambient temperatures from -50°C to 100°C

Not disturb the blade aerodynamics

Overview of Available Actuators

Piezo Electric Actuator

The 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 strain

Piezo Electric Actuator (contd.)

SMA Ice deicing system

SHAPE MEMORY ALLOY DE-ICING TECHNOLOGY Shape 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 & weight

Less energy consumption

Resistance to corrosion, abrasion

One Way SMA in Leading Edge

Types: 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°

External resistance heating system

NiTi is used:

highly durable

4% elastic deformation Memory strain 8% Permanent deformation > 5%

after million cycle

SMA– heated by electric heater

Reverse Transformation

occurs

Shearing action developed

Ice deposit peel off into the air

Forward Transformation

Debonding Action

• 0.1-0.3% shear strain sufficient to debond ice deposits

• Once ice removed, SMA is cooled by ambient air

Span wise Positioning

Chord wise Positioning

Positioning Shape Memory Alloy in the Leading edge

Block Diagram of Current Pulse generator

Block Diagram of Active State Sheet

Questions are welcome !!!