Riti Singh

• BSc 1st Class Hons in Physics - and a DIC from Imperial College
• Professor Emeritus at Cranfield University

Aero gas turbine maintenance strategies are likely to see profound changes in the future. The remarkable size of the aftermarket for both military and civil aero gas turbines has already changed the nature of the business case. The aftermarket is large, more lucrative and not subject to the cyclical downturns of the original equipment sales. The co...

An increase in environmental awareness in both the aviation industry and the wider global setting has led to large bodies of research dedicated to developing more sustainable technology with a lower environmental impact and lower energy usage. The goal of reducing environmental impact has necessitated research into revolutionary new technologies th...

The growing global environmental awareness has motivated the search for more fuel- efficient aircraft propulsion systems. In this context, a configuration based on distributed propulsion with Boundary Layer Ingestion (BLI) has been found to present potential performance benefits. The concept has been documented and explored extensively during the l...

The performance of propulsion configurations with boundary layer ingestion (BLI) is affected to a large extent by the level of distortion in the inlet flow field. Through flow methods and parallel compressor have been used in the past to calculate the effects of this aerodynamic integration issue on the fan performance; however high-fidelity throug...

Studies such as those by NASA predict large performance benefits when integrating Distributed Propulsion (DP) with the Blended Wing Body (BWB) aircraft configuration. This is because the BWB planform geometry is particularly suited to the ingestion of boundary layer air. The present study evaluates the relative benefit of DP through a comparison wi...

Although aviation based emissions are not the major sources of atmospheric pollution, their impact around the airport vicinity and the increase in air transport makes it a concern. Water injection on aircraft engines can reduce NOx emissions around the airports significantly. This has been demonstrated in research study by NASA Glenn Research Cente...

Radical aircraft and propulsion system architecture changes may be required to continue historic performance improvement rates as current civil aircraft and engine technologies mature. Significant fuel-burn savings are predicted to be achieved through distributed propulsion, where an array of propulsors is distributed along the span of an aircraft...

In this work, the Techno-economic Environmental Risk Analysis framework, a multi-disciplinary optimisation tool developed by Cranfield University, is utilised in conjunction with an in-house optimiser to carry out aircraft engine cycle optimisation processes. The central point here is the evaluation of the capabilities of the in-house optimiser for...

Los beneficios potenciales que representa la aviación en los campos: económico, de seguridad y de desarrollo tecnológico de un país, han motivado a países como Ecuador a fomentar el crecimento de la aeronáutica en los últimos años. La manufactura de vehículos no tripulados y satélites, por ejemplo, han significado importantes pasos en la evolu-ción...

The performance prediction of axial flow compressors and turbines still relies on the stationary testing of blade cascades. Most of the blade testing studies are done for operating conditions close to the design point or in off-design areas not too far from it. However, blade – and consequently engine -performance remain unexplored at relatively fa...

Engine maintenance costs are a major contributor to the direct operating costs of aircraft. Therefore, the minimization of engine maintenance costs per flight-hour is a key aspect for airlines to operate successfully under challenging market conditions. Minimization can be achieved by increasing the on-wing time or by reducing the shop-visit costs....

Greetings to you, colleagues. It is with pleasure both Prof Riti Singh and I present Vol. 86 No. 6 of the Aircraft Engineering and Aerospace Technology (AEAT) Journal as a special issue devoted to distributed propulsion and hybrid-energy topics. Prof Singh is Professor Emeritus of Gas Turbine Engineering at Cranfield University and serves as one of...

Purpose – 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 f...

Suitable models and software were integrated to provide a life assessment tool for aero jet engine blades. The approach combines aircraft and engine performance, turbine blade sizing, heat transfer, finite element analysis (FEA), and thermo-mechanical fatigue life assessment (TMF) using the Neu/Sehitoglu (N/S) TMF model. For a typical medium range...

The performance benefits of boundary layer ingestion in aircraft with distributed propulsion have been extensively studied in the past. These studies have indicated that propulsion system integration issues such as distortion and intake pressure losses could mitigate the expected benefits. This paper introduces and develops a methodology that enabl...

This work describes initial results obtained from an ongoing research involving the development of optimization algorithms which are capable of performing multi-disciplinary aircraft trajectory optimization processes. A short description of both the rationale behind the initial selection of a suitable optimization technique and the status of the op...

Purpose ‐ This article aims to investigate a selected number of liquid hydrogen storage tank parameters in a turboelectric distributed propulsion concept. Design/methodology/approach ‐ In this research study, tank structure, tank geometry, tank materials and additional physical phenomenon such as hydrogen boil-off and permeation are considered. A p...

Modern gas turbine combustor design is a complex task which includes both experimental and empirical knowledge. Numerous parameters have to be considered for combustor designs which include combustor size, combustion efficiency, emissions and so on. Several empirical correlations and experienced approaches have been developed and summarised in lite...

This paper investigates properties and traits of hydrogen with regard to environmental concerns and viability in near future applications. Hydrogen is the most likely energy carrier for the future of aviation, a fuel that has the potential of zero emissions. With investigation into the history of hydrogen, this study establishes issues and concerns...

Boundary layer ingestion by fans in propulsion system improves the propulsive efficiency. However, inlet flow distortion will dramatically eliminate these benefits. This paper puts forward a method to deal with inlet flow distortions and examines their impacts on turbofan performance at engine design point. The method models both radial and circumf...

The WebEngine is a web-based gas turbine performance simulation tool. The main advantage from this approach is the ease-of-use as no local installation is required. A number of different user categories such as students, researchers, gas turbine operators etc. can immensely benefit from this tool. The WebEngine has been under development for two ye...

A fundamental shift in propulsion system design was needed to satisfy future aircrafts' strict emission and fuel consumption requirements. The turboelectric distributed propulsion system (TeDP) uses electricity to transmit power from the core turbine to number of fans. This novel concept can dramatically increase bypass ratio to achieve lower fuel...

The history of aero gas turbines is a history of innovation. Every challenge presented to the aero engine industry has been met with ingenuity, and today engineers continue to work on innovative concepts to meet the next set of challenges facing the aviation industry. This chapter will discuss past, present and future drivers for aero gas turbine d...

A mechanical device such as an aircraft gas turbine engine will in its lifetime of service show the effects of damage and deterioration. The damage to (and deterioration of) an engine has an adverse effect on the engine's overall performance. It is therefore vitally important to predict the effects of deterioration on the performance of an engine a...

Engine maintenance costs for civil aircraft largely depend on the life consumption of critical parts like high-pressure turbine blade and disk. Severity (defined as a measure of relative damage) can be used to characterize the degree of life consumption for the parts subjected to low cycle fatigue, creep, and oxidation as predominant life-limiting...

Numerical modeling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modeling, common practice is to replace the atomizer's swirlers with velocity profiles boundary conditions, ver...

Discharging green house gases and particulates into the atmosphere has an impact on the global climate. With this current trend of increasing awareness towards the environment alternative fuels are again being examined to reduce the impact of emissions. Hydrogen is perceived as the only long term solution to global warming concerns. It is also the...

Innovations in propulsion system have been the key driver for the progress in air transportation and it is expected to grow at a rapid pace. This incurs challenges in aircraft noise reduction and regulation of hazardous emissions. This paper address the issues associated to reduction in hazardous emissions by investigating the properties and traits...

Addition of hydrogen as an additive in gas turbine combustor shows large benefit with respect to both performance and reduction in NOx levels. Due to complexity associated with dual fuel injection, it has not been implemented in gas turbines. In this study a novel combustor concept is proposed whereby a hydrogen rich mixture is synthesised within t...

Emission targets for aviation are continuously increasing as the impact of pollution and its effect on the global climate are becoming more attentive. Hydrogen has been publicized to be a fuel that can achieve very low emissions being a long term solution as an energy carrier. Although low emissions in hydrogen combustion can only be achieved when...

Continuous requirements for more efficient, greener aircrafts drive the design and analysis of novel propulsion configurations. A promising concept is expected to be the distribution of propulsion systems along the span of the wing. One of the benefits from distributed propulsion is the ingestion of the boundary layer that develops on the suction s...

In 2005, NASA released plans of next generation commercial airplane for 2030, with a cross-disciplinary effort on: reduced fuel consumption, aviation reliability, fundamental noise reduction and shorter take-off length. Meeting these requirements will need a fundamental shift in aircraft and engine design. Turboelectric distributed propulsion syste...

Continuous requirements for more efficient aircrafts lead to the design and analysis of novel propulsion configurations, with an example being the boundary layer ingestion. The complexity and integration challenges in such aircraft synergistic propulsion system characterize the research in this field, driven by the potential benefits. The aim of th...

A tool to evaluate the turbine cooling air schedule during the flight path is presented. The method is suitable for complex gas turbine engine models where accurate calculation of thermodynamic parameters of a cooling flow used for studies such as specific fuel consumption (SFC), lifing, and operating cost analysis. The method is also applicable fo...

The most uncertain and challenging part in the design of a gas turbine has long been the combustion chamber. There has been large number of experimentations in industries and universities alike to better understand the dynamic and complex processes that occur inside a combustion chamber. This study concentrates on gas turbine combustors as a whole,...

Numerical modelling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modelling, common practice is to replace the atomizer’s swirlers with velocity profiles boundary conditions, v...

The needed shift in next generation aircraft design is expected to bring novel concepts for civil aviation as the jet-flap wing. The aircraft efficiency improvements with the jet-flap wing directs its use for future aircraft designs reinforced by the tendency for more synergistic systems as active flow control, boundary layer ingestion and distribu...

The energy generation industry faces new challenges and requirements. The fourth generation of nuclear power plants is developed to meet the future clean energy demand by 2030. The supercritical carbon dioxide (S–CO2) Brayton closed cycle features compactness and high efficiency, combined with short construction time, standing for higher profitabil...

In this article, various aspects of thermo-fluid modelling for gas turbines are described and the impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building ad...

One of the certification requirements that a jet engine has to fulfil is its altitude relight capability. Relighting an aero gas turbine engine at high altitudes is more challenging than at sea level conditions. The pressure, air velocity, and temperature within the combustor at such conditions are very low, hindering the fuel atomization and evapo...

Modern advanced engines are expected to operate with higher combustor temperature rise and lower emissions. These development trends result in more combustor design difficulties. High temperature rise requires more air for complete combustion, hence reducing the amount of cooling air. Emissions consist of CO2, UHC, NOx, smoke and water vapor. CO2 i...

Sub-idle is a very challenging operating region as the performance of a gas turbine engine changes significantly compared with design conditions. In addition, the regulations for new and existing engines are becoming stricter and the prediction of engine relight capability is essential. In order to predict the performance of an engine, detailed com...

New design concepts of micromix concept based combustors have been proposed in this study and its feasibility has been checked using computational fluid dynamics. The proposed micromix concept type combustors will help in more rapid mixing of hydrogen with air and will lead to wider flammability range for the hydrogen-air flames as compared to kero...

We all know that we have limited resource of petro-chemical fuels which will last for another 40-50 odd years. In comparison to petro-chemical fuels, nuclear fuels does not produce greenhouse gases, therefore it will not contribute to global warming. Substantial literature is available for alternative fuels, which includes hydrogen, bio fuels, elec...

The design of axial compressors is dictated by the maximisation of flow efficiency at on design conditions whereas at part speed the requirement for operation stability prevails. Among other stability aids, compressor variable geometry is employed to rise the surge line for the provision of an adequate surge margin. The schedule of the variable van...

A design of a hydrogen fuelled micromix concept based combustor is proposed in this paper. The proposed micromix concept based combustor yields improved mixing, which leads to wider flammability range of the hydrogen-air flames compared to conventional kerosene and micromix concept based combustors. This improved mixing allows the combustion zone t...

Reduction in CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction in engine nacelle drag and weight. Conventional turbofan designs, however, that reduce CO2emissions-such as increased overall pressure ratio designs-can increase the production of NOx emissions. In the present work, funde...

This paper investigates performance prediction techniques for compressor blades operating under highly negative incidence angle which is typical during engine groundstarts or windmilling relights. Although this is a very frequently occurring situation during the life of an aero engine, turbomachinery components are rarely tested under those conditi...

As a consequence of increased stringent engine emission regulations, in a highly competitive market, it has become necessary to explore innovative, economic and environmentally friendly cycles to sustain competitive advantages. Among these innovative cycles, both the geared and the direct drive counter-rotating open rotors, due to their relatively...

Sub-idle is a very challenging operating region, as the performance of a gas turbine engine changes significantly compared to design conditions. In addition, the regulations for new and existing engines are becoming stricter and the prediction of engine relight capability is essential. In order to predict the performance of an engine, detailed comp...

After a shaft failure the compression system of a gas turbine is likely to surge due to the heavy vibrations induced on the engine after the breakage. Unlike at any other conditions of operation, compressor surge during a shaft over-speed event is regarded as desirable as it limits the air flow across the engine and hence the power available to acc...

The performance prediction of axial flow compressors and turbines still relies on the stationary testing of blade cascades. Most of the blade testing studies are done for operating conditions close to the design point or in off-design areas not too far from it. However, blade – and consequently engine - performance remain unexplored at relatively f...

This paper evaluates the constant volume combustion (CVC), the open rotor (OR) and constant volume combustion with open rotor (CVCOR) engine technologies as propulsion systems in subsonic aircraft. Available simulation codes are used to compare different engine technologies assuming the same level of technology investment, to identify the cycle opt...

Several gas-turbine-behaviour simulation programs have been developed so far to predict gas turbines performances under design and off-design conditions. The focus of the present investigation is on addressing the effects of the different approaches to modelling the gases’ thermodynamic properties on the performance prediction of gas turbines, in p...

Over the past few years, great concern has been raised about the impact of commercial aviation on the environment. In a Business As Usual approach, the expected growth in air traffic is going to affect climate change even more unless mitigation policies are devised and implemented. Although there is a tendency to focus on long-term technological so...

Aviation provides a vital part of the world’s transport system and generates revenue for companies. Nevertheless, the predicted annual growth of air traffic will cause environmental issues. The European Union and European aviation industry formulated a vision for the year 2020. They foresee that a step change in technology is required to meet futur...

Growth in air traffic and airport neighboring communities has resulted in increased pressure to severely penalize airlines that do not meet strict local noise and emissions legislation, and also to charge airlines and passengers with noise and emission fees. The objective of this research is to assess the trade-off between fuel burn, NOx emissions...

The behaviour of the Pratt and Whitney F100-PW229 low-bypass turbofan engine has been employed as the benchmark in this investigation of the attributes of a novel engine concept and in particular the potential of a two-combustor engine for military fighter applications. Because of the lack of complete commercially-classified information concerning...

The performances achievable with conventional engine-cycles may be reaching their limits. Preliminary results show that two-combustor engines can achieve larger flight envelopes and higher thrusts, but at the expenses of higher fuel-consumption rates when compared with those for comparable conventional engines. A simple transient-behaviour predicti...

A penalty is incurred in trading off improved performance (e.g. greater acceleration and maximum-speed achievable) against a wider operating-envelope for an aircraft. Preliminary predictions show that two-combustor engines have wider envelopes and higher thrusts, but at the expense of higher fuel-consumption rates when compared with conventional en...

The climatic effects of air-traffic pollutants, such as carbon dioxide (CO2) and mononitrogen oxides (NOx), aerosols, contrails, and aviation induced cirrus clouds, are repeatedly stressed in assessment reports. It is therefore desired to reduce all aviation emissions simultaneously. In this paper, a novel propulsion concept, which has the potentia...

In this two-part publication, various aspects of thermo-fluid modelling for gas turbines are described and their impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation...

In this two-part publication, various aspects of thermo-fluid modelling for gas turbines are described and their impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation...

The conventional Brayton CPC (constant pressure combustion) cycle engines have almost reached maturity in terms of thermal efficiency and SFC (specific fuel consumption). With environmental norms taking the front seat in civilian applications, the goal is to think of innovative concepts that are faster, cheaper, cleaner and quieter. Among many prop...

As aviation is one of the fastest growing industrial sectors world wide, air-traffic emissions are projected to increase their stake in the contribution to global warming. According to studies, both carbon dioxide and contrails are the principal air-traffic pollutants, whereas the impact from contrails in terms of radiative forcing is possibly larg...

Principles of Turbomachinery in Air–Breathing EnginesBaskharoneE. A.Cambridge University Press, The Edinburgh Building, Shaftesbury Road, Cambridge, CB2 2RU. 2006. 580pp. Illustrated. £70. ISBN 0-521-85810-0. - Volume 112 Issue 1136 - Riti Singh

In order to achieve a larger operating envelope for an aircraft, the fuel-consumption rate of its engine(s) has to be increased. The design and off-design behaviours of a two-combustor engine, i.e. involving a relatively new and novel engine cycle, have been analyzed. The results show that two-combustor engines generate higher maximum-achievable th...

The performances achievable with conventional engine-cycles may be reaching their limits. A penalty is incurred in trading off performance (e.g. acceleration and maximum-speed achievable) against a wide operating-envelope requirement for the aircraft. High-performance propulsion systems usually emit easily detectable infrared-energy signatures, whi...

As aviation is one of the fastest growing industrial sector world wide, air-traffic emissions are projected to increase their stake in the contribution to global warming. According to recent studies, both CO2 and contrails will be the principal air-traffic pollutants. Since the environmental impact of contrails is potentially larger, their avoidanc...

Greenhouse gas emissions, contrails, and aviation-induced cirrus clouds are the principal pollutants from air traffic, which contribute to the anthropogenic global warming. Recent climate assessments have stressed the importance of contrails and aviation-induced cirrus clouds because they may contribute more than all other aircraft emissions combin...

Elements of Propulsion: Gas Turbines and Rockets – Second editionMattinglyJ.D.American Institute of Aeronautics and Astronautics, 1801 Alexander Bell Drive, Suite 500, Reston, VA 20191-4344, USA. 2006. 867pp. Illustrated. $79.95 (AIAA members), $109.95 (non-members). ISBN 1-56347-779-3. - Volume 111 Issue 1116 - Riti Singh

Recent climate assessments have stressed the importance of perturbations in the Earth's radiation budget caused by air traffic. They are caused by the emission of greenhouse gases, aerosols, contrails and aviation induced cirrus clouds. The contribution from contrails and cirrus clouds might be larger than that of all other aircraft emissions combi...

A hierarchical approach to gas path diagnostic for a two-shaft simple gas turbine involving multiple neural networks has been presented. The described methodology has been tested with data not used for training, and generalisation is found to be appropriate for actual application of this technique. In addition, the level of accuracy achieved by thi...

Mainly owing to the dwindling fossil oil resources and the environmental concerns of discharging greenhouse gases into the atmosphere, it is essential to find an alternative to kerosene for civil aviation. This paper covers the main effects on aero engines when changing to hydrogen fuel. Particularly, emission and performance issues are discussed,...

The main objective of the paper is to evaluate the potential of reducing the environmental impact of civil subsonic aviation by using hydrogen fuel. The paper is divided into three parts of which this is Part I, where the background, prospects and Challenges of introducing an alternative fuel in aviation are outlined. In Part II the aero engine des...

The main objective of the paper is to evaluate the potential of reducing the environmental impact of civil subsonic aviation by using hydrogen fuel. The paper is divided into three parts of which this is Part II. In Part I the background, prospects and challenges of introducing an alternative fuel in aviation were outlined. In this paper, Part 11,...

The main objective of the paper is to evaluate the potential of reducing the environmental impact of civil subsonic aviation by using hydrogen fuel. The paper is divided into three parts of which this is Part III. In Part I the background, prospects and challenges of introducing an alternative fuel in aviation were outlined. The aero engine design...

Greenhouse gas emissions, contrails and artificially induced cirrus clouds are the principal pollutants from air traffic which contribute to the anthropogenic global warming. Recent climate assessments have stressed the importance of contrails and aviation induced cirrus clouds. They might contribute more than all other aircraft emissions combined....

Elements of Gas Turbine Propulsion Mattingly J.D. American Institute of Aeronautics and Astronautics, 1801 Alexander Bell Drive, Reston, VA 20191, USA. 2005. 960pp. Illustrated. $79.95 (AIAA members), $109.95 (non-members). ISBN 1-56347-778-5. - Volume 110 Issue 1104 - Riti Singh

This paper presents the development of an integrated fault diagnostics model for identifying shifts in component performance and sensor faults using Genetic Algorithm and Artificial Neural Network. The diagnostics model operates in two distinct stages. The first stage uses response surfaces for computing objective functions to increase the explorat...

Given the maturity of the gas turbine user industry, and the quality of the original equipment manufactured, the field experience of these machines has been broadly very good. Nonetheless, there can be difficulties in managing availability and reliability, and the costs of unscheduled shut downs can be extremely large. Advanced gas turbine performa...

In this paper economic and scenario analyses of new gas turbine combined cycles with no emissions of carbon dioxide (CO2 ) and nitrogen oxides are described. The cycles, already presented in a recent paper (ASME GT 2002-30117), have water/steam as working fluid, the compression phase both in liquid and vapour phase, the internal combustion between...

Despite inflating unit-fuel costs, the long-term prospects for the aircraft industry remain buoyant. Nevertheless reducing direct operating-costs is crucial to ensure competitive advantages for airlines and manufacturers, and so effective advanced engine-condition monitoring methodologies are desirable. Hence gas-path diagnostic methods are reviewe...

The majority of scientists today are in agreement that discharging greenhouse gases into the atmosphere has an impact on the global climate. Furthermore, the dwindling fossil oil resources raise concerns. Finding an alternative to kerosene for civil aviation is thus essential. Taking a completely new approach for civil aviation by fuelling with liq...

Gas turbines (GT) are used for aero and marine propulsion, power generation and as mechanical drives for a wide range of industrial applications. Often, they are affected by gas path faults which have hitherto been diagnosed by techniques such as fault matrixes, fault trees and gas path analysis (GPA). In this paper, an artificial neural network (A...

In the context of the reduction of the carbon dioxide (CO2 ) emissions as prescribed by the Kyoto protocol, this paper describes a thermodynamic performance analysis of new gas turbine combined cycles with no emissions of CO2 and nitrogen oxides. Three new similar cycles belonging to the same typology are proposed. These cycles use water/steam as w...

Traditionally engine fault diagnosis has been performed at steady state conditions. There are several problems which can only be detected by transient data analysis like bearing fault, some control problems etc.. In addition, gas turbine performance deviation due to a component fault is more likely to be magnified during transients, when compared w...

A marine engineer is often confronted with the problem of repairs/maintenance at sea. However, an advance warning of the impending problem can greatly help in scheduling maintenance more efficiently by storing appropriate spares and positioning suitable expertise. The ability to predict the remaining operational life of marine gas turbine engines i...