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Article
Publication date: 1 December 2000

J. Yin, P. Pilidis, K.W. Ramsden and S.D. Probert

The requirements imposed upon advanced short take‐off and vertical landing (ASTOVL) aircraft give rise to challenging demands on their propulsion systems. One possible approach is…

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Abstract

The requirements imposed upon advanced short take‐off and vertical landing (ASTOVL) aircraft give rise to challenging demands on their propulsion systems. One possible approach is to have a high‐performance turbofan of traditional design and an additional, but separate, fan to provide a major part of the lift during the take‐off and landing manoeuvres. For such a design, there are several quite‐different choices of layout for providing the power to drive the remote fan by means of the core engine. These include shaft‐driven and bleed‐driven options. The choice will depend on the anatomy and required thermodynamic‐performance of the whole system. In this paper, several pertinent alternative engine‐designs are discussed. Four of these, based on a high‐performance low‐bypass‐ratio core engine, are studied in detail and their behaviours compared. Prima facie, the preferred choice is the engine with the shaft‐driven fan. A slightly less acceptable choice is the high‐pressure turbine exit‐bleed driven remote‐fan.

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Aircraft Engineering and Aerospace Technology, vol. 72 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 23 February 2021

Mosab Alrashed, Theoklis Nikolaidis, Pericles Pilidis, Soheil Jafari and Wael Alrashed

Recent advancements in electrified transportation have been necessitated by the need to reduce environmentally harmful emissions. Accordingly, several aviation organisations and…

360

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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

Originality/value

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.

Details

International Journal of Productivity and Performance Management, vol. 71 no. 5
Type: Research Article
ISSN: 1741-0401

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Article
Publication date: 14 August 2017

Panagiotis Loukopoulos, George Zolkiewski, Ian Bennett, Pericles Pilidis, Fang Duan and David Mba

Centrifugal compressors are integral components in oil industry, thus effective maintenance is required. Condition-based maintenance and prognostics and health management…

366

Abstract

Purpose

Centrifugal compressors are integral components in oil industry, thus effective maintenance is required. Condition-based maintenance and prognostics and health management (CBM/PHM) have been gaining popularity. CBM/PHM can also be performed remotely leading to e-maintenance. Its success depends on the quality of the data used for analysis and decision making. A major issue associated with it is the missing data. Their presence may compromise the information within a set, causing bias or misleading results. Addressing this matter is crucial. The purpose of this paper is to review and compare the most widely used imputation techniques in a case study using condition monitoring measurements from an operational industrial centrifugal compressor.

Design/methodology/approach

Brief overview and comparison of most widely used imputation techniques using a complete set with artificial missing values. They were tested regarding the effects of the amount, the location within the set and the variable containing the missing values.

Findings

Univariate and multivariate imputation techniques were compared, with the latter offering the smallest error levels. They seemed unaffected by the amount or location of the missing data although they were affected by the variable containing them.

Research limitations/implications

During the analysis, it was assumed that at any time only one variable contained missing data. Further research is still required to address this point.

Originality/value

This study can serve as a guide for selecting the appropriate imputation method for missing values in centrifugal compressor condition monitoring data.

Details

Journal of Quality in Maintenance Engineering, vol. 23 no. 3
Type: Research Article
ISSN: 1355-2511

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Article
Publication date: 1 December 2000

J. Yin, R. Hales, P. Pilidis, B. Curnock and R. Meads

A two‐dimensional high‐bypass ratio turbofan performance model was developed in order to predict accurately gas turbine transient performance. In the present model, the fan of…

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Abstract

A two‐dimensional high‐bypass ratio turbofan performance model was developed in order to predict accurately gas turbine transient performance. In the present model, the fan of high bypass engines has strong radial profiles of all thermodynamic variables. It is common to average these profiles so that the fan can be represented by one or two one‐dimensional characteristics. The present paper describes how the radial profiles can be used to make an estimation of turbofan transient performance. The results are somewhat different to those produced using two one‐dimensional compressor performance maps.

Details

Aircraft Engineering and Aerospace Technology, vol. 72 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Available. Content available
580

Abstract

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 6
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 7 August 2019

Hoi-Yin Sim, Rahizar Ramli and Ahmad Saifizul

The purpose of this paper is to examine the effect of reciprocating compressor speeds and valve conditions on the roor-mean-square (RMS) value of burst acoustic emission (AE…

120

Abstract

Purpose

The purpose of this paper is to examine the effect of reciprocating compressor speeds and valve conditions on the roor-mean-square (RMS) value of burst acoustic emission (AE) signals associated with the physical motion of valves. The study attempts to explore the potential of AE signal in the estimation of valve damage under varying compressor speeds.

Design/methodology/approach

This study involves the acquisition of AE signal, valve flow rate, pressure and temperature at the suction valve of an air compressor with speed varrying from 450 to 800 rpm. The AE signals correspond to one compressor cycle obtained from two simulated valve damage conditions, namely, the single leak and double leak conditions are compared to those of the normal valve plate. To examine the effects of valve conditions and speeds on AE RMS values, two-way analysis of variance (ANOVA) is conducted. Finally, regression analysis is performed to investigate the relationship of AE RMS with the speed and valve flow rate for different valve conditions.

Findings

The results showed that AE RMS values computed from suction valve opening (SVO), suction valve closing (SVC) and discharge valve opening (DVO) events are significantly affected by both valve conditions and speeds. The AE RMS value computed from SVO event showed high linear correlation with speed compared to SVC and DVO events for all valve damage conditions. As this study is conducted at a compressor running at freeload, increasing speed of compressor also results in the increment of flow rate. Thus, the valve flow rate can also be empirically derived from the AE RMS value through the regression method, enabling a better estimation of valve damages.

Research limitations/implications

The experimental test rig of this study is confined to a small pressure ratio range of 1.38–2.03 (free-loading condition). Besides, the air compressor is assumed to be operated at a constant speed.

Originality/value

This study employed the statistical methods namely the ANOVA and regression analysis for valve damage estimation at varying compressor speeds. It can enable a plant personnel to make a better prediction on the loss of compressor efficiency and help them to justify the time for valve replacement in future.

Details

International Journal of Structural Integrity, vol. 10 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 30 September 2014

P. Laskaridis, V. Pachidis and P. Pilidis

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…

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Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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.

Originality/value

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.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 11 October 2018

Amare D. Fentaye, Aklilu T. Baheta and Syed Ihtsham Ul-Haq Gilani

The purpose of this paper is to present a quantitative fault diagnostic technique for a two-shaft gas turbine engine applications.

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Abstract

Purpose

The purpose of this paper is to present a quantitative fault diagnostic technique for a two-shaft gas turbine engine applications.

Design/methodology/approach

Nested artificial neural networks (NANNs) were used to estimate the progressive deterioration of single and multiple gas-path components in terms of mass flow rate and isentropic efficiency indices. The data required to train and test this method are attained from a thermodynamic model of the engine under steady-state conditions. To evaluate the tolerance of the method against measurement uncertainties, Gaussian noise values were considered.

Findings

The test results revealed that this proposed method is capable of quantifying single, double and triple component faults with a sufficiently high degree of accuracy. Moreover, the authors confirmed that NANNs have derivable advantages over the single structure-based methods available in the public domain, particularly over those designed to perform single and multiple faults together.

Practical implications

This method can be used to assess engine’s health status to schedule its maintenance.

Originality/value

For complicated gas turbine diagnostic problems, the conventional single artificial neural network (ANN) structure-based fault diagnostic technique may not be enough to get robust and accurate results. The diagnostic task can rather be better done if it is divided and shared with multiple neural network structures. The authors thus used seven decentralized ANN structures to assess seven different component fault scenarios, which enhances the fault identification accuracy significantly.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 6
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 December 1997

Alan Wood and Pericles Pilidis

Describes a novel concept in aircraft propulsion: investigates a variable cycle jet engine for a supersonic advanced short take‐off vertical landing (ASTOVL) aircraft. The engine…

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Abstract

Describes a novel concept in aircraft propulsion: investigates a variable cycle jet engine for a supersonic advanced short take‐off vertical landing (ASTOVL) aircraft. The engine is the selective bleed turbofan. The selective bleed turbofan is a two shaft, three compressor, variable cycle gas turbine. At subsonic flight speeds it operates as a medium bypass turbofan. It becomes a low bypass turbofan when flying faster and is capable of supersonic cruise in the dry mode. A preliminary design of an ASTOVL aircraft from Cranfield, the S‐95, was used as the vehicle. Outlines the performance of the engine and its integration with the aircraft. Explains off‐design engine performance characteristics and describes variable geometry requirements. The major advantage of this engine is that all the components are employed all the time, for all operating modes, thus incurring low weight penalties. Predicts that the aircraft/ engine combination will perform in a satisfactory way, meeting most performance targets provided that some improvements are carried out.

Details

Aircraft Engineering and Aerospace Technology, vol. 69 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 4 July 2008

Colin F. McDonald, Aristide F. Massardo, Colin Rodgers and Aubrey Stone

This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on…

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Abstract

Purpose

This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less noise.

Design/methodology/approach

Aeroengine performance analyses were carried out covering a wide range of parameters for more complex thermodynamic cycles. This led to the identification of major component features and the establishing of preconceptual aeroengine layout concepts for various types of recuperated and ICR variants.

Findings

Novel aeroengine architectures were identified for heat exchanged turboshaft, turboprop, and turbofan variants covering a wide range of applications. While conceptual in nature, the results of the analyses and design studies generally concluded that heat exchanged engines represent a viable solution to meet demanding defence and commercial aeropropulsion needs in the 2015‐2020 timeframe, but they would require extensive development.

Research limitations/implications

As highlighted in Parts I and II, early development work was focused on the use of recuperation, but this is only practical with compressor pressure ratios up to about 10. For today's aeroengines with pressure ratios up to about 50, improvement in SFC can only be realised by incorporating intercooling and recuperation. The new aeroengine concepts presented are clearly in an embryonic stage, but these should enable gas turbine and heat exchanger specialists to advance the technology by conducting more in‐depth analytical and design studies to establish higher efficiency and “greener” gas turbine aviation propulsion systems.

Originality/value

It is recognised that meeting future environmental and economic requirements will have a profound effect on aeroengine design and operation, and near‐term efforts will be focused on improving conventional simple‐cycle engines. This paper has addressed the longer‐term potential of heat exchanged aeroengines and has discussed novel design concepts. A deployment strategy, aimed at gaining confidence with emphasis placed on assuring engine reliability, has been suggested, with the initial development and flight worthiness test of a small recuperated turboprop engine for UAVs, followed by a larger recuperated turboshaft engine for a military helicopter, and then advancement to a larger and far more complex ICR turbofan engine.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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