Operating characteristics of a high radius pre-swirl cooling system

An experimental investigation into pre-swirl effectiveness and receiver hole discharge coefficient characteristics for a high radius injection pre-swirl cooling systems was carried out on a physically representative experimental rig with a 450 mm diameter rotor.The receiver holes and pre-swirl nozzle were located at a radius of 181 mm and 180 mm respectively.The experimental work was mainly conducted at 5 000～12 000 r/min,4 bar absolute pressure and 1.132 kg/s air supply.The maximum air supply temperature was 190 ℃.Pressure and temperature distributions in the pre-swirl system were examined with an emphasis on the velocity effectiveness of the pre-swirl system as a whole and on the discharge coefficients of the rotating 'receiver holes' in the rotor.The results showed that the velocity effectiveness increased with increasing swirl ratio resulting in reduced blade cooling flow temperature.Different seal flow configurations caused very different effectiveness at different speeds,but outflow through the inner and outer seals always gave the highest effectiveness compared other configurations.Increasing the seal flow rate reduced the effectiveness.For the coefficient of discharge,except for the low speed range,it increased with increase in swirl ratio for most speeds.

Light-weighting in aerospace component and system design

Light-weighting involves the use of advanced materials and engineering methods to enable structural elements to deliver the same,or enhanced,technical performance while using less material.The concept has been extensively explored and utilised in many industries from automotive applications to fashion and packaging and offers significant potential in the aviation sector.Typical implementations of light-weighting have involved use of high performance materials such as composites and optimisation of structures using computational aided engineering approaches with production enabled by advanced manufacturing methods such as additive manufacture,foam metals and hot forming.This paper reviews the principal approaches used in light-weighting,along with the scope for application of light-weighting in aviation applications from power-plants to airframe components.A particular area identified as warranting attention and amenable to the use of lightweighting approaches is the design of solar powered aircraft wings.The high aspect ratio typically used for these can be associated with insufficient stiffness,giving rise to non-linear deformation,aileron reversal,flutter and rigid-elastic coupling.Additional applications considered include ultralight aviation components and sub-systems,UAVs,and rockets.Advanced optimisation approaches can be applied to optimise the layout of structural elements,as well as geometrical parameters in order to maximise structural stiffness,minimise mass and enable incorporation of energy storage features.The use of additive manufacturing technologies,some capable of producing composite or multi-material components is an enabler for light-weighting,as features formally associated with one principal function can be designed to fulfil multiple functionalities。

Future aircraft cabins and design thinking:optimisation vs.win-win scenarios

With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakeholders to consider new forms of aircraft and technology.Customer requirements are recognized as a key driver in business.The airline is the principalcustomer for the aircraft manufacture.The passenger is,in turn,the airline's principal customerbut they are just one of several stakeholders that include aviation authorities,airport operators,air-traffic control and security agencies.The passenger experience is a key differentiator usedby airlines to attract and retain custom and the fuselage that defines the cabin envelope for thein-flight passenger experience and cabin design therefore receives significant attention for newaircraft,service updates and refurbishments.Decision making in design is crucial to arrivingat viable and worthwhile cabin formats.Too litle innovation will result in an aircraftmanufacturer and airlines using its products falling behind its competitors.Too much mayresult in an over-extension with,for example,use of immature technologies that do not havethe necessary reliability for a safety critical industry or sufficient value to justify the develop-ment effort.The multiple requirements associated with cabin design,can be viewed as an area for optimisation,accepting trade-offs between the various parameters.Good design,however,is often defined as developing a concept that resolves the contradictions and takes the solutiontowards a win-win scenario.Indeed our understanding and practice of design allows forbehaviors that enhance design thinking through divergence and convergence,the use ofabductive reasoning,experimentation and systems thinking.This paper explores and definesthe challenges of designing the aireraft cabin of the future that will deliver on the multiplerequirements using experiences from the A350 XWB and future cabin design concepts.Inparticular the paper explores the value of implementing design thinking insights in engineeringpractice and discusses the relative merits of decisions based on optimisation versus win-winscenarios for aircraft cabin design and wider applications in aerospace environments.Theincreasing densification of technological opportunities and shifting consumer demand coupledwith highly complex systems may ultimately challenge our ability to make decisions based onoptimisation balances.From an engineering design perspective optimisation tends to precludecertain strategies that deliver high quality results in consumer scenarios whereas win-winsolutions may face challenges in complex technical environments.

Using morphological analysis to tackle uncertainty at the design phase for a safety critical application

The gas turbine engine internal air system provides cooling and sealing air to a series of critical subsystems and components such as high pressure gas turbine blades,as well as controlling the thrust load on the turbine and compressor spool assembly.Many potential variations for the internal air system are possible,depending on the requirement,expertise and command of intellectual property.Some subsystems,such as rim seals,pre-swirl systems,and rotating cavities have been the subject of extensive development and analysis leading to robust design solutions.Nevertheless there remains scope for further consideration of the overall system design,and this paper explores the use of a decision analysis tool called morphological analysis applied to the internal air system.Morphological analysis provides an effective means for tackling issues where there is uncertainty,as is the case with many design scenarios,including the internal air system,with some specific parameters and information not available until later in the design phase,after the key geometry has been defined.The problem space comprising seven principal parameters,and a cross consistency matrix which allows identification of compatible and incompatible states are presented.