Fan Cowl Research Articles

Study on the Influence of Fan and Fan Cowl on Intake Air Parameters of Cooling Module

Abstract Due to the increase in heat load, the demand for heat dissipation of the cabin cooling module has increased. The fan arrangement and the design of the fan cowl can significantly affect the intake air parameters, thereby affecting the performance of the heat exchangers. In this paper, the whole vehicle model was set up and the effect of the fan installation distance, the fan cowl coverage ratio, and the radial extension of the fan cowl outlet was researched by numerical simulation. The results show that due to the relative position of the layout of the cooling module, the effect of the fan arrangement and the fan cowl design on the intake parameters of the radiator is greater than that of the intercooler. The improvement of the air velocity uniformity can reduce the intake air average temperature for better heat dissipation, a 2% improvement in air intake velocity uniformity can lead to a 6% reduction in air intake average temperature event at a low air mass flow. The greater installation distance of the fan or the higher closing degree of the fan cowl, the more favorable intake parameters to ensure the better cooling performance of the heat exchangers. Moreover, when the fan cowl coverage ratio reaches 0.9, the air intake average temperature increases by 5.6%, which means that the fan cowl coverage should not be too high. This study will provide useful reference information for the design of cooling modules in the cabin.

Design optimisation of non-axisymmetric exhausts for installed civil aero-engines

Future civil aero-engines are likely to operate with higher bypass-ratios (BPR) than current power-plants to improve propulsive efficiency and reduce specific thrust. This will probably be accompanied by an increase of fan diameter and size of the power plant. Consequently, future configurations are likely to require more close-coupled installations with the airframe due to structural and ground clearance requirements. This tendency may lead to an increase in the adverse installation effects which could be mitigated with non-axisymmetric exhausts. However, due to the prohibitive computational cost, limited regions of the design space have been studied. For this reason, a relatively low-cost design approach for the integrated system is required. The aim of this work is to establish a method to map the non-axisymmetric exhaust design space where the effects of the propulsion system installation are taken into account. The methodology relies on the generation of a design database using inviscid computational fluid dynamics (CFD) methods. This is used to characterise the design space, identify the dominant design parameters and build response surface models for optimisation. The candidate designs that arise from the optimisation are assessed with viscous CFD simulations to assess the aerodynamic mechanisms and performance characteristics. The result is a set of design recommendations for installed configurations with non-axisymmetric exhausts. The method is an enabler for the optimisation of installed propulsion systems and has provided an exhaust design with a 0.7% improvement on net vehicle force relative to an axisymmetric exhaust, for a close coupled configuration where the fan cowl is overlapped with the wing. A reduction in net vehicle force is expected to lead to a similar reduction in cruise fuel burn.

Structural optimization of engine nacelle fan cowl door hinge

To increase propulsive efficiency, future nacelle engines are projected to run at low specific thrust with large bypass ratios. Typically, this entails a larger fan diameter and nacelle, as well as increased drag and weight penalties. As a result, there is a need to construct more compact, nacelles’ components in comparison to present designs in order to minimize drag and weight. These designs are naturally more difficult, necessitating the use of a system to explore and identify the design area that is possible. Designing a nacelle is difficult due to the wide range of operational circumstances. This paper provides a multi-objective optimization technique for fan cowl door component of nacelle design utilizing an evolving genetic algorithm. A collection of geometry definitions utilizing Class Shape Transformations, automated simulation and analysis, a generic algorithm, assessments at various nacelle operating circumstances, and the addition of extra aerodynamic restrictions are all part of the unique framework. This framework was used to look into the nacelle design space for nacelle components. For the new nacelle component design challenge, multi-objective optimization was successfully shown, and the entire system was proved to allow the discovery of the feasible nacelle design space. Moreover, in this paper a series of fan cowl door hinge is designed from the scratch and optimized step by step for reducing the weight of the component without compromising for the stress capacity and load transformations within the allowable limit.

Prediction of frequency and spatially dependent attenuation of guided waves propagating in mounted and unmounted A380 parts made up of anisotropic viscoelastic composite laminates

Monitoring damage in composite structures using guided wave-based techniques is particularly effective due to their excellent ability to propagate over relatively long distance and hence to cover a large area with few testing time and equipment. The industrialization of this method is highly tributary of the number and placement of the active elements. Yet, the optimal sensorization of a structure relies on the decrease in amplitude of guided waves over propagation distance. A reliable prediction of attenuation of guided waves is still a challenge especially for anisotropic viscoelastic composite materials which exhibit complex changes of attenuation with propagation direction and thus a spatial dependency of attenuation. In this paper, the damped global matrix method (dGMM), having stable and efficient merits, is developed to predict the frequency and spatially dependent attenuation of waves propagating in anisotropic composite materials. dGMM integrates three damping models (Hysteretic, Kelvin-Voigt, and Biot models) into the conventional undamped GMM to consider viscoelasticity of composite laminates. The proposed dGMM is first theoretically validated by numerical comparison with the semi-analytical finite element method. In addition, two industrial case studies, parts of an A380 nacelle at scale one, are employed to experimentally validate the proposed attenuation prediction method. The first one is a fan cowl structure and the second one is an inner fixed structure, both either unmounted or mounted on an actual instrumented A380 plane. This makes the validation extremely valuable for both the scientific and industrial communities. The proposed attenuation prediction method thus paves the way to optimally deploy sensor network for structural health monitoring of anisotropic viscoelastic composite structures.

Optimization strategy for performance improvement of a lift fan cowl lip based on panel method

Optimization strategy for performance improvement of a lift fan cowl lip based on panel method

The use of hybrid intuitive class shape transformation curves in aerodynamic design

The inherent mathematical smoothness of intuitive class shape transformation (iCST) curves has been shown to be suitable for the design of aerodynamic shapes. However, this property means that any changes to a constraint are not local but will result in a modification to the whole curve. This poses a problem to the aerodynamic designer when different parts of the curve are required to fulfil particular design requirements. A Hybrid iCST (HiCST) parameterisation approach is proposed which allows two sections of a single aero-line curve to be decoupled, without geometric discontinuity, whilst maintaining the dimensionality of a design problem. The HiCST approach has been tested on two key aerodynamic components of an aero-engine. Firstly, a design space exploration and optimisation were carried out for an aero-engine fan cowl. A comparison of Pareto fronts showed a 3.9% reduction in the minimum achievable nacelle drag from the iCST to the HiCST parameterisation. Secondly, aero-engine intakes were designed with both the iCST and HiCST parameterisations. The HiCST intake showed improved aerodynamic performance in terms of DC60 and IPR and proved more insensitive to changes in massflow and incidence. This development of the method for an aero-engine fan cowl and intake highlights the potential aerodynamic benefit from the proposed HiCST method.

A Mobile Application of Augmented Reality for Aircraft Maintenance of Fan Cowl Door Opening

A Mobile Application of Augmented Reality for Aircraft Maintenance of Fan Cowl Door Opening

Optimal dual-PZT sizing and network design for baseline-free SHM of complex anisotropic composite structures

Structural health monitoring (SHM) processes for aeronautic composite structures are generally based on the comparison of healthy and unknown databases. The need for prior baseline signals is one of the barriers to industrial deployment and can be avoided with baseline-free SHM (BF-SHM) methods, based on the attenuations and reflections of symmetric and antisymmetric Lamb wave modes attributable to damage. A promising mode decomposition method is based on the use of dual-PZTs (concentric disc and ring electrodes lying on a single piezoelectric transducer of lead zirconate titanate). However, the performance of such methods highly depends on the Lamb wave mode properties (propagation speed and attenuation , which vary with material orientation and inter-PZT distance), the number and the sensitivity of the dual-PZT to each mode (which depends on the frequency and element size). Considering these constraints, an original three-step process able to design a full dual-PZT network and the optimal range of excitation frequencies to consider on a highly anisotropic and arbitrarily complex aeronautic structure is presented. First, the dispersion curves of Lamb waves in the investigated material together with the minimal size of the damage to detect are used to estimate the size of the dual-PZT, as well as convenient excitation frequencies. A local finite element model representative of the full-scale structure is then used to estimate the optimal distance and orientation between neighboring PZT elements. Finally, a network optimization solver applies these parameters to place dual-PZTs on the fan cowl of an aircraft nacelle and provides a candidate network covering the whole structure.

The airbus A320 family fan cowl door safety modification: a human factors scenario analysis

Purpose The Airbus A320 family engine fan cowl doors (FCDs) safety issue is known to the industry for almost 18 years; however, it has not been addressed adequately by the aircraft manufacturer and the various operators and regulating authorities. The purpose of this paper is to examine in a systematic way the possible operational and safety implications of a new modification on the engine FCDs. Design/methodology/approach An array of error-prone scenarios is presented and analysed under the prism of human factors in a non-exhaustive qualitative scenario analysis. Findings All examined scenarios are considered more or less probable. A number of accident prevention solutions are proposed for each of the scenario examined, in view of the acceptance and implementation of this modification by operators. Research limitations/implications As these scenarios are neither exhaustive nor have been tested/validated in actual aircraft maintenance practice, the further analysis is necessary. A substantial follow-up survey should take place, which should include a wider array of scenarios. This would allow obtaining the necessary data for a quantitative (statistical) analysis. Practical implications This case study identifies issues in relation to this modification, introduced by Airbus and the European Aviation Safety Agency (EASA), which may prove problematic from the point of view of safety effectiveness and disruption of operations. Originality/value This case study examines a long-standing aviation safety issue and the implications of a solution proposed by the aircraft manufacturer and adopted by EASA. This can be useful in increasing the awareness around these issues and highlight the importance of a human-centric and scenario-based design of engineering modifications towards minimising error in aircraft technical operations.

Topology optimization and additive manufacturing for aerospace components

One of the main challenges for the aerospace industry nowadays lies in weight reduction of aircraft components without compromising their structural functionalities. With that goal, structural and topology optimization show up as a combination of design and modelling techniques. Based on the finite element method (FEM), component optimization consists of removing material which is dispensable, keeping proper functioning of the modelled part. The result is an optimized geometry, usually with a complex shape, which is possible to manufacture thanks to additive manufacturing (AM) technologies. In this paper, the topological optimization methodology has been used to redesign the following components: (1) a connector support of the VEGA space launcher, (2) a typical lever component from civil aircrafts and (3) housing part from fan cowl structures. In all of the cases, a significant weight reduction has been reached without major impact on their mechanical behaviour. Finally, components (1) and (2) were manufactured by laser beam melting (LBM) technology to demonstrate the possibility of the couple, optimization and AM concepts, as a way to improve the future aerospace structures.

Estimation of the temperature field on a composite fan cowl using the static capacity of surface-mounted piezoceramic transducers.

The influence of temperature on SHM (Structural Health Monitoring) systems using guided waves is a major problem for their industrial deployment. One of the cheapest SHM process developed in aeronautical context is based on piezoelectric transducers mounted on the monitored structure. Several methods are used to assess the presence of damage. A popular one is based on tracking changes in the electromechanical impedance of the transducers: it is an efficient damage indicator around the device and can also be used as a fault diagnosis indicator for the transducer itself. However, monitoring decisions need to be robustified with temperature sensors also mounted on the structure. In this article, the electromechanical impedance is used to determine the temperature on each lead zirconate titanate transducer (PZT). This avoids supplementary instrumentation and the entire temperature field of the structure is estimated. The proposed approach is tested experimentally on a on a small composite plate and then on a real part of an A3 80 composite nacelle. Results show that the temperature field on the structure can be estimated with a precision of ±5 °C using a linear regression between static capacity and temperature.

An Automated Approach to Nacelle Parameterization Using Intuitive Class Shape Transformation Curves

A tool to create parametric aerodynamic shapes using intuitive design variables based on class shape transformation (CST) curves is presented. To enable this, a system has been developed which accepts arbitrary constraints and automatically derives the analytical expressions which describe the corresponding class shape transformation curves. Parametric geometry definitions for fan cowl and intake aero-lines were developed using the generalized method. Computational fluid dynamics (CFD) analysis of the fan cowl shows that despite the simple geometry definition, its performance characteristics are close to what would be expected of a finished design. The intake geometry was generated in a similar way and met the typical performance metrics for conventional intakes. This demonstrates the usefulness of the tool to quickly and robustly produce parametric aero-lines with good aerodynamic properties, using relatively simple intuitive design variables.

Flow Field Analysis and Optimization Design of Fan Cover for the Duct System of the Split Air Conditioner’s Outdoor Unit

The green characteristic of household split air conditioners can be inproved by reducing the noise or improving the energy efficiency. Therefore, a finite element model of outdoor units duct system was built with Fluent considering the coupling of separated components. Based on the simulation results, the flow field of duct system was analyzed, and the structure of fan cowl was optimized to decrease the export eddy. Experiments were done to proved the effectiveness of the modelling and optimizing process.

The response of honeycomb sandwich panels under low-velocity impact loading

This paper describes the results of an experimental investigation and a numerical simulation on the impact damage on a range of sandwich panels. The test panels are representative of the composite sandwich structure of the engine nacelle Fan Cowl Doors of a large commercial aircraft. The low-velocity impact response of the composites sandwich panels is studied at five energy levels, ranging from 5 to 20 J, with the intention of investigating damage initiation, damage propagation, and failure mechanisms. These impact energy levels are typically causing barely visible impact damage (BVID) in the impacted composite facesheet. A numerical simulation was performed using LS-DYNA3D transient dynamic finite element analysis code for calculating contact forces during impact along with a failure analysis for predicting the threshold of impact damage and initiation of delaminations. Good agreement was obtained between numerical and experimental results. In particular, the numerical simulation was able to predict the extent of impact damage and impact energy absorbed by the structure. The results of this study is proving that a correct numerical model can yield significant information for the designer to understand the mechanism involved in the low-velocity impact event, prior to conducting tests, and therefore to design a more efficient impact-resistant aircraft structure.

Flight investigations of the effect of yaw on the intake and fan nozzle flow of a natural laminar flow nacelle

AbstractTwo major technologies in aeronautics promise substantial improvements in the fields of economy and ecology. One is laminar flow technology and the other arises from new developments related to aircraft turbofan engines. The trend in turbofan engine development is towards engines possessing higher bypass ratios. This, however, entails larger engine dimensions, leading not only to an increase in the skin friction drag but also to negative engine-airframe interactions. As a consequence, the need for laminar flow nacelles becomes all the more important as part of the general process of engine-air-frame integration optimisation for advanced transport aircraft.This paper deals with some results obtained from flight tests with a laminar flow nacelle demonstrator and specifically addresses the topic of aerodynamics of intakes and nozzles. The results described relate to a European collaborative programme in which a natural laminar flow (NLF) nacelle was flight tested. Results of the effect of the angle of yaw on the static pressure distribution on the fan cowl including the intake of an NLF nacelle are presented for the maximum cruise flight condition. At zero yaw, a comparison of Euler calculations with flight test data is made. Measured flow variables of the fan nozzle flow directly downstream of the fan nozzle exit, exemplified by the Mach number and the flow density distributions, are also presented for the condition of maximum cruise.

Determination of mechanical resonances in induction motors by random modulation and acoustic measurement

Acoustic noise emission from PWM-VSI inverter driven induction motors is a well-known problem. The generated noise depends mainly on two factors: the harmonic content of the supply voltage waveform; and the mechanical resonance frequencies of the induction motor. It is necessary to know the mechanical resonances to optimize the switching scheme of the inverter to reduce the noise emission. Measuring the resonance frequencies is normally a laborious process. This paper introduces a new method for estimating the mechanical resonances from acoustic noise measurements. Employing random modulation of the output voltage of the inverter, the voltage spectrum can be spread over a wide frequency range. Using the spectrum analysis of the measured acoustic noise, the resonances can easily be estimated as the dominant frequencies of the acoustic noise spectrum. The method was tested on a 2.2 kW induction motor at no load and full load. Some of the mechanical resonances of the motor at no load were calculated by the Holzer method. The calculations showed good agreement with the sound measurements. The influence of the fan cowl was investigated and it is concluded that this is an important factor in the acoustic noise emission. Finally, it was observed that new mechanical resonances appeared when the induction motor was loaded by a pump drive system, and they were estimated by the measurement technique. >

Design of an advanced nacelle for a very high bypass ratio engine

AbstractThe next challenge for future engines is to increase the bypass ratio in order to improve the propulsive efficiency. These very high bypass ratio engines improve the fuel consumption but create new technical challenges. These challenges include the fact that larger engines require bigger nacelles, hence the external drag and weight increase; furthermore the installation of these engines on civil aircraft is more challenging. Therefore important work has been carried out to optimise the design of these new nacelles and their installation on the airframe.The present work is based on a new engine, with a very high bypass ratio. For this engine Snecma has designed an advanced nacelle with a low diameter-low length fan cowl and a core cowl mounted thrust reverser. A very short secondary flow nozzle is required to improve accessibility to the core engine and its accessories. The fan cowl length is dramatically reduced.Different solutions were investigated to design the inlet and the fan cowl. Based on 2D potential inverse codes and 3D Euler codes, CFD calculations were made to optimise the aerodynamic lines for cruise conditions while keeping good off-design performance. A highly challenging exhaust nozzle was designed to maintain good efficiency with very tough geometric constraints. For this Snecma used 2D Navier-Stokes CFD codes. New reverse systems were studied for this type of nacelle, for example core cowl mounted thrust reversers. The optimisation of these highly 3D geometries was performed using 2D and 3D Navier-Stokes calculations.

Investigation of very high bypass ratio engines for subsonic transports

A study of propulsion system performance for a family of high bypass ratio turbofan engines is presented. The bypass ratio range is from 6 to 17.5, and both bare engine performance and nacelle installation performance have been considered. Geared, variable pitch/variable nozzle engines with bypass ratios of 10.6, 14, and 17.5 have been studied parametrically, and the performance of a fixed pitch, gearless engine of bypass ratio 9.6 has been estimated to represent an advanced engine with conventional mechanical complexity. Nacelle performance data for a bypass 5 engine have also been included as a baseline. Thrust reverser design for these engines is also considered. Results of this study indicate that conventional nacelle installation losses do not reverse the trend of improving engine fuel efficiency with bypass ratio out to at least bypass ratio 17.5. If innovative concepts are used, such as reverse thrust from a reverse fan pitch and a short fan cowl, the installed fuel efficiency for highbypass-ratio engines looks even better. The bypass 9.6 engine shows a lower fuel burn benefit than the bypass 17.5 engine, but it offers the potential of reduced mechanical complexity and lower maintenance cost.

ターボファンエンジン騒音低減対策に関する研究

The fan noise characteristics of a turbofan engine and fan noise abatement technology have been studied by the authors.The study was concentrated on the theoretical analysis of the spinning mode propagating from the rotating fan of a high bypass-ratio turbofan engine and the practical technology to abate the fan noise and the practical technology to abate the fan noise acoustic linings on the engine inlet duct and the fan cowl. Through the above study, the procedures to determine the optimum impedance and necessary dimensions on the acoustic treatment for the reduction of the fan rotating noise under given conditions were obtained. Following those procedures, acoustically lined ducts were designed, manufactured and installed on a high bypass-ratio turbofan engine for a series of noise measuring tests. As a result, it was revealed that the acoustically lined duct attached to the engine inlet is effective for the reduction of the noise level so long as it is designed to the optimum impedance value for maximizing the attenuation rate of the spinning mode, and that some portions of the spinning mode can be cut off even by the solid wall duct, though this was not realized in the simulation test using a plane wave source.