CHANGING AIRCRAFT ENGINE TECHNOLOGIES

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Be it natural progression, organic growth or technological evolution, aircraft engine maintenance and manufacturing are undergoing quick but small changes that is planned for long-lasting impact – specifically with a focus on sustainability.  With the clarion call sounded by world leaders covering sectors to drastically reduce GHG and carbon emissions and its damaging effect on our planet, Aviation must do its bit and remains very much in the spotlight. Reaching the Net Zero finishing line by 2050 is on everybody’s horizon.

There are few big engine makers who have pushed forward their revolutionary concepts and ideas on how to reduce fuel burn, tackle the GHG effect, make passenger cabins quieter and overall, run sustainable aviation companies. Enhancing passenger comfort by enabling quieter cabins is also a result of that R & D that newer aircraft engine technologies have brought about. At the same time, focus has remained on fuel efficiency of engines, making use of SAF, use of blended materials – alloys and polymers to reduce weight, items that cost less, yet result in producing more powerful and efficient aircraft engines.

Out-of-the-box ideas like adding gearboxes within the engines, making use of digitisation and 5G technology that are linked to sensors that help garner and crunch crucial big data, use of artificial intelligence (AI) on a real-time basis that leads to fuel efficiency, noise reduction, and increases the Mean Time Between Failure (MTBF) – all delivering safety, sustainability, and passenger comfort.

Here are some noteworthy examples of (at times), decade long experimentations in aeronautical engineering.

GEARBOX MOUNTED ENGINES

Pratt & Whitney have produced after much R & D, a path breaking technological marvel, in association with NASA – the Pratt & Whitney PurePower Geared Turbofan (GTF) engine series. The company has incorporated a gearbox that connects with the fan in the front of the engine, and to the turbine in the rear. The gearbox allows the rotors to spin at different speeds, where whatever be the front fan speed, the rear turbine of the engine spins three times faster in that same period.

Several of these technological advancements have resulted in GTF engines having reduced noise levels by nearly 25%, and an even greater achievement has been an impressive 75% reduction in carbon footprint.

While the fan in front runs at slower speeds, it causes less vibrations caused by air turbulence and noise from fan blades. However, at lower speeds it also sucks in more air. This means that lighter blade materials can be opted for, reducing machining costs, or even having a smaller number of fan blades, making it more economical to manufacture these engines.  

Again, with the fan rotating at low Revolutions Per Minute (RPM), the engine’s lifetime maintenance costs are reduced. Additionally, the brand has introduced cutting edge technology in aircraft engines like the open fan architecture, as also hybrid electric engines, for which much testing and experiments are ongoing.

Use of Argon gas to generate electricity, is yet another option, for its ability to generate plasma that can in turn generate streams of electrons. These electrons can then be used to augment the energy produced by aero engines. This method is still in its experimental stage.

COUNTER-ROTATING FAN

Innovations in engine technology such as counter rotating fans, entail fixing twin fans in the front, where one spins clockwise and the other anti-clockwise. This enables spinning at lower speeds, but are sucking in a lot more air, compared to a single fan mounting even though operating at a higher RPM. The large amount of air sucked in by the two counter-rotating fans enables the engine designers to reduce the number of engine blades needed to push the air rearwards in each individual fan. This will again reduce manufacturing cost.

Air sucked in through counterrotating fans into the engine generates less air turbulence, and naturally low noise, and vibrations, thereby according passengers with a more calmer relaxing flight. Other positive outcomes are reduced wear and tear, making MRO costs comparatively less, and use of lighter or blended materials like alloys reduce capital expenditure. All this is directly linked to business viability and sustainability.

HYBRID POWERED ENGINES

Businesses are increasingly switching from burning fossil fuels for power generation, to electrification of their systems. Accordingly, Boeing’s 787 variant has successfully cut over to hybrid power for its operations. However, to accommodate the battery, (which has a heavier storage density than the storage density of Aviation Turbine Fuel), that generates power, aeronautical engineers looked at altering and reducing the airframe weight by 20%. Much research is on with a view to profitability in the future. Significant resources are being deployed towards reducing the dead-weight of the battery, by moving towards lighter and efficient batteries. Certain OEMs are running trials on their hybrid-electric engines that when after an aircraft takes off. The main power switches to electricity, drawn from batteries other than using ATF for the entire duration of the flight.

DIGITALISATION

Applications like Internet of Things (IoT) and Artificial Intelligence (AI) over 5G technology will be in use more and more for safe and optimal operating performance of operating pilots. Close to real-time instructions can be passed on the aircraft or pilot for enhancing their productivity.

INFORMATION AND COMMUNICATION TECHNOLOGY

With the advent of sensors, performance parameters of the assemblies, sub-assemblies, and components of the engines can be monitored on a real-time basis. This includes, flight performance readings produced by the sensors can be quickly transmitted to computing systems either onboard or on ground using 5G and Internet of Things (IoT) technologies. The big data thus garnered are then put through analysis.

ALTERNATE AVIATION TECHNOLOGIES IN VOGUE

Aircraft designers and OEMs are now utilising 3-D printing technologies or applying additive manufacturing to fabricate components and sub-assemblies for designing and manufacturing engines or prototypes. Cost benefits are advantageous especially during ongoing designing and research work on engine prototypes, as also for spares manufacturing required during MRO services. Companies can save on their inventory carrying costs.

BIOFUEL ADDITIVES

In order to offset the huge cost of ATF, and to reduce the adverse impact on the environment due to emissions, experiments are ongoing using blended fuel. Here conventional ATF is blended with biofuel to create SAF or Sustainable Aviation Fuel. This helps pare down operating costs and lessens the carbon footprint of the aircraft.

MAGENTIC BEARINGS

Magnetic bearings help reduce surface-to-surface contact between moving parts. Thus, the wear and tear of these parts are greatly reduced, and so is the cost of maintenance and inventory-holding.

KEY PLAYERS

Engine manufacturers endeavour to make engines lighter and stronger. Certain leading OEMs are working on electric and hybrid propulsion systems for both profitability and to realise sustainability goals. Here are the major players and their achievements in bringing about changes in engine technologies:

ROLLS-ROYCE

‘UltraFan,’ the pathbreaking aero engine from the Rolls-Royce stable has been successfully tested using 100% SAF. In the large aero engine category this variant has demonstrated improvement in efficiency by 10%. The new geared architecture ensures that the fan, compressors, and turbines all run at optimum speed. The UltraFan engine is the engine of the future. The fan casing and blades are made from carbon fibre, a material which is likely to save a 20% weight in comparison with earlier used materials.

REACTION ENGINES

UK engine manufacturer, Reaction Engine’s rocket engine Sabre is a game changer that is replacing, in a way, the conventional propulsion system. Sabre – Synergetic Air Breathing Rocket Engine is a revolutionary class of aero engines that propel both high speed aircraft and spacecraft. The engine’ USP is its calibre to execute fuel efficiency of a jet engine with the power and speed delivered by a rocket. Reaction Engines’ SABRE engines are capable of Mach 5.4 in air-breathing mode, and Mach 25 in rocket mode for space flight.

CFM INTERNATIONAL

CFM International’s advanced LEAP engine renowned amongst their global customers as an industry benchmark for fuel efficiency, and is gaining huge popularity in the commercial aircraft space. The speciality here is that the LEAP nozzle premixes fuel and air to provide lean burn combustion, setting it apart from the traditional combustors that mix these elements inside the combustion chamber. LEAP engine customers are benefitted by nearly 15% in fuel efficiency as well as CO₂ emissions. These engines have seen reduction in NOx emissions and lowered engine noise, meaning quieter flights for onboard passengers.

INNOVATION IN ENGINE TECHNOLOGIES TO MAKE FLYING GREE

Be it in the designing, newer materials/alloys used, with sound, emission, and de-carbonization improvements, the industry remains very much in focus. Hence aerospace as a sector is looking at all kinds of incremental changes in the present, while addressing the needs of the future. Globally, innovation and improvement in aero engines carry on unabated.

The rising necessity and preference of air travel also puts pressure on the aerospace industry to do it’s part.

Reference Credit: sps-aviation.com