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The performance benefits of boundary layer ingestion (BLI) in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by numerous studies. Therefore, it is well known that increased inlet flow distortion due to BLI can dramatically reduce these benefits. In this context, a methodology that enables the assessment of different propulsion architectures, whilst accounting for these aerodynamic integration issues, is studied in this paper.

To calculate the effects of BLI-induced distortion, parametric and parallel compressor approaches have been implemented into the propulsion system analysis. The propulsion architectures study introduces the concept of thrust split between propulsors and main engines and also examines an alternative propulsor configuration. In the system analysis, optimum configurations are defined using thrust-specific fuel consumption as figure of merit.

For determined operating conditions, the system analysis found an optimum configuration for 65 per cent of thrust delivered by the propulsor array, which was attributed mainly to the influence of the propulsor’s intake losses. An alternative propulsor design, which used the ejector pump effect to re-energize the boundary layer, and avoiding the detrimental effects of BLI are also cited in this work.

To summarize, this paper contributes with a general review of the research that has been undertaken to tackle the aforementioned aerodynamic integration issues and, in this way, make viable the implementation of distributed propulsion systems with BLI.

The application of thermal barrier coatings (TBCs) allows aero-engine blades to operate at higher temperatures with higher efficiency. The preparation of the TBCs increases the surface roughness of the blade, which impacts the thermal cycle life and thermal insulation performance of the coating. To reduce the surface roughness of blades, particularly the blades with small size and complex curvature, this paper aims to propose a method for industrial robot polishing trajectory planning based on on-site measuring point cloud.

The authors propose an integrated robotic polishing trajectory planning method using point cloud processing technical. At first, the acquired point cloud is preprocessed, which includes filtering and plane segmentation algorithm, to extract the blade body point cloud. Then, the point cloud slicing algorithm and the intersection method are used to create a preliminary contact point set. Finally, the Douglas–Peucker algorithm and pose frame estimation are applied to extract the tool-tip positions and optimize the tool contact posture, respectively. The resultant trajectory is evaluated by simulation and experiment implementation.

The target points of trajectory are not evenly distributed on the blade surface but rather fluctuate with surface curvature. The simulated linear and orientation speeds of the robot end could be relatively steady over 98% of the total time within 20% reduction of the rest time. After polishing experiments, the coating roughness on the blade surface is reduced dramatically from Ra 7–8 µm to below Ra 1.0 µm. The removal of the TBCs is less than 100 mg, which is significantly less than the weight of the prepared coatings. The blade surface becomes smoothed to a mirror-like state.

The research on robotic polishing of aero-engine turbine blade TBCs is worthwhile. The real-time trajectory planning based on measuring point cloud can address the problem that there is no standard computer-aided drawing model and the geometry and size of the workpiece to be processed differ. The extraction and optimization of tool contact points based on point cloud features can enhance the smoothness of the robot movement, stability of the polishing speed and performance of the blade surface after polishing.

In a boundary layer ingestion (BLI) propulsion system, the fan operates continuously under distorted inflow conditions, leading to an increment of aerodynamic loss and in turn impacting the potential fuel burn reduction of the aircraft. Usually, in the preliminary design stage of a BLI propulsion system, it is essential to assess the impact of fuselage boundary layer fluids on fan aerodynamic performances under various flight conditions. However, the hub region flow loss is one of the major loss sources in a fan and would greatly influence the fan performances. Moreover, the inflow distortion also results in a complex and highly nonlinear mapping relation between loss and local physical parameters. It will diminish the prediction accuracy of the commonly used low-fidelity computational approaches which often incorporate traditional physics-based loss models, reducing the reliability of these approaches in evaluating fan performances. Meanwhile, the high-fidelity full-annulus unsteady Reynolds-averaged Navier–Stokes (URANS) approach, even though it can give rather accurate loss predictions, is extremely time-consuming. This study aims to develop a fast and accurate hub loss prediction method for a BLI fan under distorted inflow conditions.

This paper develops a data-driven hub loss prediction method for a BLI fan under distorted inflows. To improve the prediction accuracy and applicability, physical understandings of hub flow features are integrated into the modeling process. Then, the key physical parameters related to flow loss are screened by conducting a sensitivity analysis of influencing parameters. Next, a quasi-steady assumption of flow is made to generate a training sample database, reducing the computational time by acquiring one single sample from the highly time-consuming full-annulus URANS approach to a cost-efficient single-blade-passage approach. Finally, a radial basis function neural network is used to establish a surrogate model that correlates the input parameters and the output loss.

The data-driven hub loss model shows higher prediction accuracy than the traditional physics-based loss models. It can accurately capture the circumferentially and radially nonuniform variation trends of the losses and the associated absolute magnitudes in a BLI fan under different blade load, inlet distortion intensity and rotating speed conditions. Compared with the high-fidelity full-annulus URANS results, the averaged relative prediction errors of the data-driven hub loss model are kept less than 10%.

The originality of this paper lies in developing a new method for predicting flow loss in a BLI fan rotor blade hub region. This method offers higher prediction accuracy than the traditional loss models and lower computational time cost than the full-annulus URANS approach, which could realize fast evaluations of fan aerodynamic performances and provide technical support for designing high-performance BLI fans.

Novel aircraft propulsion configurations require a greater integration of the propulsive system with the airframe. As a consequence of the closer integration of the propulsive system, higher levels of flow distortion at the fan face are expected. This distortion will propagate through the fan and penalize the system performance. This will also modify the exhaust design requirements. This paper aims to propose a methodology for the aerodynamic optimization of the exhaust for novel embedded propulsive systems. To model the distortion transfer, a low order throughflow fan model is included.

As the case study a 2D axisymmetric aft-mounted annular boundary layer ingestion (BLI) propulsor is used. An automated computational fluid dynamics approach is applied with a parametric definition of the design space. A throughflow body force model for the fan is implemented and validated for 2D axisymmetric and 3D flows. A multi-objective optimization based on evolutionary algorithms is used for the exhaust design.

By the application of the optimization methodology, a maximum benefit of approximately 0.32% of the total aircraft required thrust was observed by the application of compact exhaust designs. Furthermore, for the embedded system, it is observed that the design of the compact exhaust and the nacelle afterbody have a considerable impact on the aerodynamic performance.

This paper presents a novel approach for the exhaust design of embedded propulsive systems in novel aircraft configurations. To the best of the authors’ knowledge, this is the first detailed optimization of the exhaust system on an annular aft-mounted BLI propulsor.

This paper aims to consider main challenges of development of advanced architectures of propulsion systems, i.e. distributed propulsion systems (DPS).

This paper is a comparative analysis of different types of DPS.

Mechanical driving DPS seems as more feasible in near-term outlook, and turboelectric and full electric DPS are imagined feasible in mid- and far-term outlook.

Additional comprehensive numerical and experimental researches are needed to approve the efficiency of DPS.

Possible impact of installation of DPS on aeroplane fuel efficiency are shown.

Application of DPS on long-range aeroplanes is new a engineering solution, which may allow to meet future advanced efficiency goals.

Recent advancements in electrified transportation have been necessitated by the need to reduce environmentally harmful emissions. Accordingly, several aviation organisations and governments have introduced stringent emission reduction targets for 2050. One of the most promising technologies proposed for achieving these targets is turboelectric distributed propulsion (TeDP). The objective of this study was to explore and identify key indicators for enhancing the applicability of TeDP in air transportation.

An enhancement valuation method was proposed to overcome the challenges associated with TeDP in terms of technological, economic and environmental impacts. The result indicators (RIs) were determined; the associated performance indicators (PIs) were analysed and the key RIs and PIs for TeDP were identified. Quantitative measurements were acquired from a simulated TeDP case study model to estimate the established key PIs.

It was determined that real-world TeDP efficiency could be enhanced by up to 8% by optimising the identified key PIs.

This study is the first to identify the key PIs of TeDP and to include a techno-economic environmental risk analysis (TERA) based on the identified key PIs. The findings could guide developers and researchers towards potential focus areas to realise the adoption of TeDP.

With the predicted rise in air traffic, a growing need exists to make the aviation industry more environmentally sustainable in the long-term future. Research has shown that the turbo-electric distributed propulsion system (TeDP) could be the next disruptive technology that has the potential to meet the ambitious environmental goals set for the N + 3 time frame. This however will require the use of superconductivity, application of high-temperature superconducting materials and cryogenic liquids. This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology.

This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology.

Implementation of superconducting technology is currently one of the greater challenges faced and hence this article also reviews some of the key considerations to enable utilisation of cryogenic fuels in the future.

This paper provides a viewpoint and reviews some of the work undertaken in the field. It also provides a perspective on some new possibilities and advantages from using TeDP with cryogenic fuels.

This chapter explores why a better alternative to current practises in addressing sovereign debt repayment problems has not emerged. It examines the discussions on financing and debt repayment difficulties from the first United Nations Conference on Trade and Development in 1964 to the eve of the 1980s debt crisis. Drawing from recent work that highlights the ways with which the power of economics and economists operates in the public realm, the chapter examines the role of economic analysis within the political debate on debt. The chapter details the repeated refusals by creditor groups to any suggestion for improvements to the international debt architecture.

The purpose of this paper is to describe the necessity for the use of fully superconducting electrical power systems (SEPS) in future hybrid electric aircraft which facilitates the use of a distributed propulsion system.

The paper looks at the overall design of the electric power systems for these applications and compares the design process of a more conventional power network with a fully superconducting one. The design issues and solutions in each case are then described.

The paper concludes that SEPS will give many advantages to the aircraft design and operation.

Significant efforts needs to be oriented towards the development of fully SEPS and dedicated facilities are required for reliable experimental data that will allow the modelling of these systems.

The requirement for more experimental work has not yet been considered by the Industry, as it is a general belief that these networks will behave similar to the conventional ones.