Pericles Pilidis

Cranfield University, Cranfield, England, United Kingdom

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Publications (69)11.85 Total impact

  • ASME Turbo Expo 2014, Duesseldorf, Germany; 06/2014
  • Theoklis Nikolaidis, Pericles Pilidis
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    ABSTRACT: The aero-thermodynamic effects of water ingestion on an axial flow compressor performance are presented in this article. Under adverse weather conditions, gas turbine engine performance deteriorates and in extreme cases, this performance deterioration may result in flameout or shutdown of the engine, which means that serious incidents or possibly accidents may occur. When the water droplets enter into the engine they break up into smaller droplets which may bounce, coalesce or splash onto the compressor blades. They also form a liquid film whose motion is influenced by inertia forces, blade friction, aerodynamic drag and pressure gradient. The water liquid film has considerable effects on blade’s geometric characteristics. Apart from the change in its profile due to thickness increase, air shear force and water droplets momentum cause waves in water film’s surface introducing a kind of ‘roughness’ on blade’s surface. The current work focuses on the aero-thermodynamic effects. Its methodology is based on computational fluid dynamics, which is used to solve the flow field of the computational domain. The model consists of an extended inlet, an inlet guide vane, a rotor and a stator blade. Several cases with water ingestion are solved, varying the parameter of water mass and engine rotational speed, simulating adverse weather conditions. On the rotor blade, the water film height and speed are calculated at the equilibrium condition. This condition is achieved when the water mass which flows out of the blade surface equals with this which impacts on it. Taking into account the film thickness at each computational node of the blade surface, the blade’s geometry is changed. Furthermore, an equivalent roughness is introduced and the effects on compressor’s performance are calculated. It is found that deterioration is more pronounced in low rotational speed. For 4% water/air, compressor’s isentropic efficiency deteriorates 8.5% for idle speed and 1.6% for full speed. For the same water mass, mass flow capacity deteriorates 2.4% at idle speed while the change is small for full speed.
    Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering 03/2014; 228(3):411-423. · 0.40 Impact Factor
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    Barinyima Nkoi, Pericles Pilidis, Theoklis Nikolaidis
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    ABSTRACT: This paper considers comparative assessment of simple and advanced cycle small-scale aero-derivative industrial gas turbines derived from helicopter engines. More particularly, investigation was made of technical performance of the small-scale aero-derivative engine cycles based on existing and projected cycles for applications in industrial power generation, combined heat and power concept, rotating equipment driving, and/or allied processes. The investigation was done by carrying out preliminary design and performance simulation of a simple cycle (baseline) two-spool small-scale aero-derivative turboshaft engine model, and some advanced counterpart aero-derivative configurations. The advanced configurations consist of recuperated and intercooled/recuperated engine cycles of same nominal power rating of 1.567 MW. The baseline model was derived from the conversion of an existing helicopter engine model. In doing so, design point and off-design point performances of the engine models were established. In comparing their performances, it was observed that to a large extent, the advanced engine cycles showed superior performance in terms of thermal efficiency, and specific fuel consumption. In numerical terms, thermal efficiencies of recuperated engine cycle, and intercooled/recuperated engine cycles, over the simple cycle at DP increased by 13.5%, and 14.5% respectively, whereas specific fuel consumption of these cycles over simple cycle at DP decreased by 12.5%, and 13% respectively. This research relied on open access public literature for data.
    Propulsion and Power Research, Elsevier. 12/2013; 2(4):243 - 253.
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    ABSTRACT: Fossil fuel accounts for over 80% of theworls primary energy, particularly in areas of transportation, manufacturing and domestic heating. However, depletion of fossil reserves, frequent threats to the security of fossil fuel supply, coupled with concerns over emissions of greenhouse gases associated with fossil fuel use has motivated research towards developing renewable and sustainable sources for energy fuels. Consequently, the use of microalgae culture to convert CO 2 from power plants flue gases into biomass that are readily converted into biofuel offers a window of opportunities to enhance, compliment or replace fossil-fuel-use. Interest in the use of microalgae biomass for biofuel production is high as it affords the potential for power plant CO 2 sequestration – (1kg of dry algae biomass uses about 1.83kg CO 2). Similarly, its capacity to utilise nutrients from a variety of wastewater, sets it apart from other biomass resources. These outlined benefits all emphasis the need for extended R&D efforts to advance commercial microalgae biofuel production. The paper is aimed at investigating the environmental performance of the microalgae biofuel production process using LCA.
    11th International Conference on Manufacturing Research (ICMR2013); 09/2013
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    ABSTRACT: This paper presents an integrated approach, targeting the comprehensive assessment of combined helicopter engine designs within designated operations. The developed methodology comprises a series of individual modeling theories, each applicable to a different aspect of helicopter flight dynamics and performance. These relate to rotor blade modal analysis, three-dimensional flight path definition, flight dynamics trim solution, aeroelasticity, and engine performance. The individual mathematical models are elaborately integrated within a numerical procedure, solving for the total mission fuel consumption. The overall simulation framework is applied to the performance analysis of the Aérospatiale SA330 helicopter within two generic, twin-engine medium helicopter missions. An extensive comparison with flight test data on main rotor trim controls, power requirements, and unsteady blade structural loads is presented. It is shown that, for the typical range of operating conditions encountered by modern twin-engine medium civil helicopters, the effect of operational altitude on fuel consumption is predominantly influenced by the corresponding effects induced on the engine rather than on airframe rotor performance. The implications associated with the implicit coupling between aircraft and engine performance are discussed in the context of mission analysis. The potential to comprehensively evaluate integrated helicopter engine systems within complete three-dimensional operations using modeling fidelity designated for main rotor design applications is demonstrated. The proposed method essentially constitutes an enabler in terms of focusing the rotorcraft design process on designated operation types rather than on specific sets of flight conditions.
    ASME Journal of Engineering for Gas Turbines and Power. 09/2013; 135(9).
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    D C Mathew, G Di Lorenzo, P Pilidis
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    ABSTRACT: Microalgae biofuel production offers a new frame of opportunities as an alternative and sustainable energy resource. Being renewable, it has potential for utilizing CO 2 (1kg of dry algae biomass uses about 1.83kg CO 2) with other GHGs from power plants' waste flue gases, along with the capacity to utilise nutrients from a variety of wastewater and the ability to yield a variety of liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. This paper presents a sustainable model process route for biodiesel production using microalgae biomass to sequester gas turbine power plant waste CO 2 . The research work is distinctive in the sense that several different technical options for key algae biomass production and conversion pathways are integrated with power plant flue gas CO 2 use in regards to their Life Cycle Assessment (LCA) impacts. Using SimaPro, we evaluate a potentially viable algae biodiesel production model in terms of energy and GHG intensity, managing the process accordingly. LCA results are cross-compared in order to identify the most significant opportunities for improvement with the final aim of developing a sustainable microalgae biofuel production model. The results show the significance of using LCA to direct future advancement of the microalgae biofuel production process.
    3rd International Exergy, Life Cycle Assessment and Sustainability Workshop & Symposium (ELCAS 3); 07/2013
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    ABSTRACT: The aim of the study presented in this paper, is to compare helicopters employing simple cycle turboshaft engines, with helicopters employing novel regenerated turboshafts. Two existing helicopter configurations, a Twin Engine Light and a Twin Engine Medium are compared against regenerated configurations. The reference installed engines of both helicopters are notionally optimized by incorporating a heat exchanger, which enables heat transfer between the exhaust gas and the compressor delivery air to the combustion chamber. This process leads to a lower fuel input requirement as well as higher overall thermal efficiency compared to the reference simple cycle engine. The benefits arising from the adoption of the heat exchanger for both configurations are firstly presented by conducting part-load performance analysis for each optimized engine against its reference simple cycle engine. The obtained results suggest substantial reduction in specific fuel consumption for a major part of the operating power range with respect to both helicopter configurations. The results also demonstrate that the heat exchanger effectiveness is a critical parameter in achieving further reductions in specific fuel consumption. The study is further extended to investigate mission fuel burn saving limits for both helicopter configurations under the simulated part-load performance conditions by conducting a heat exchanger tradeoff study. The weight estimation correlation for the heat exchanger is adopted from the previously reported studies of similar fashion and is simulated accordingly for both helicopter configurations. A multi-disciplinary simulation tool with an integrated range of capabilities applicable to helicopter performance evaluation and mission analysis is adopted to simulate various types of missions, targeting wide range of helicopter operations. The results of the mission analysis suggest that the regenerated counterpart configurations are capable of achieving significant reductions in mission fuel burn. However, the level of gain from mission fuel burn savings is dependent on the selected helicopter mission profile, the recuperator design effectiveness as well as the overall evaluation criteria. The results also conclude that while the amount of benefit is dependent on various parameters, there is always an optimum “saving” region for each mission that justifies the need for regeneration.
    ASME Turbo Expo 2013: Turbine Technical Conference and Exposition; 06/2013
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    ABSTRACT: This paper presents an integrated approach, targeting the comprehensive assessment of combined helicopter–engine designs, within designated operations. The developed methodology comprises a series of individual modeling theories, each applicable to a different aspect of helicopter flight dynamics and performance. These relate to rotor blade modal analysis, three-dimensional flight path definition, flight dynamics trim solution, aeroelasticity and engine performance. The individual mathematical models are elaborately integrated within a numerical procedure, solving for the total mission fuel consumption. The overall simulation framework is applied to the performance analysis of the Aérospatiale SA330 helicopter within two generic, twin-engine medium helicopter missions. An extensive comparison with flight test data on main rotor trim controls, power requirements and unsteady blade structural loads is presented. It is shown that, for the typical range of operating conditions encountered by modern twin-engine medium civil helicopters, the effect of operational altitude on fuel consumption is predominantly influenced by the corresponding effects induced on the engine, rather than on airframe–rotor performance. The implications associated with the implicit coupling between aircraft and engine performance, are discussed in the context of mission analysis. The potential to comprehensively evaluate integrated helicopter–engine systems within complete three-dimensional operations, using modeling fidelity designated for main rotor design applications, is demonstrated. The proposed method essentially constitutes an enabler in terms of focusing the rotorcraft design process on designated operation types, rather than on specific sets of flight conditions.
    ASME Turbo Expo 2013: Turbine Technical Conference and Exposition; 06/2013
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    Barinyima Nkoi, Pericles Pilidis, Theoklis Nikolaidis
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    ABSTRACT: This paper focuses on investigations encompassing comparative assessment of gas turbine cycle options. More specifically, investigation was carried out of technical performance of turboshaft engine cycles based on existing simple cycle (SC) and its projected modified cycles for civil helicopter application. Technically, thermal efficiency, specific fuel consumption, and power output are of paramount importance to the overall performance of gas turbine engines. In course of carrying out this research, turbomatch software established at Cranfield University based on gas turbine theory was applied to conduct simulation of a simple cycle (baseline) two-spool helicopter turboshaft engine model with free power turbine. Similarly, some modified gas turbine cycle configurations incorporating unconventional components, such as engine cycle with low pressure compressor (LPC) zero-staged, recuperated engine cycle, and intercooled/recuperated (ICR) engine cycle, were also simulated. In doing so, design point (DP) and off-design point (OD) performances of the engine models were established. The percentage changes in performance parameters of the modified cycle engines over the simple cycle were evaluated and it was found that to a large extent, the modified engine cycles with unconventional components exhibit better performances in terms of thermal efficiency and specific fuel consumption than the traditional simple cycle engine. This research made use of public domain open source references.
    Propulsion and Power Research. 06/2013; 2(2):96–106.
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    ABSTRACT: SUMMARY An engineering-economic analysis of the behaviours of each of two pre-combustion gas-turbine combined cycles with CO2 capture (an Integrated Gasification Combined Cycle (IGCC) and an Integrated Reforming Combined Cycle (IRCC)) is described. Their economic performances have been evaluated in terms of the break-even electricity selling price. The results show that the proposed pre-combustion power plant efficiency values (37% and 43.7% for the IGCC and the IRCC respectively) are significantly lower compared to a conventional plant value (55.3%). The CO2 emissions of the latter are less than half those of the conventional plant. Introducing an hypothetical carbon tax equal to 50£/tCO2, the break-even selling price (BESP) for the proposed IGCC and IRCC plants is 4.40 p/kWh and 4.10 p/kWh respectively, while for the conventional plant amounts to 4.73 p/kWh. A sensitivity analysis has been carried out by varying the most influential investment parameters. The analysis has revealed that, considering the uncertainties associated with these key parameters, a substantial risk that the BESP could exceed the first value obtained is so prominent in some cases to alter their ranking order with respect to the most competitive technology. The final part of the analysis is a Monte-Carlo simulation to determine the impact of simultaneous variations of all the variables, subject to uncertainty, on the break-even selling unit price for the generated electricity. From the simulation, it derives that the BESP value ranges from 3.13 p/kWh to over 6.00 p/kWh for the IGCC case with a 50% probability of exceeding the first value obtained (4.40 p/kWh). In the IRCC case, the range of possible value for the BESP is from 2.85 p/kWh to 6.10 p/kWh, and there is a 60% probability that the actual BESP would exceed the first value obtained (4.10 p/kWh). Copyright © 2013 John Wiley & Sons, Ltd.
    International Journal of Energy Research 04/2013; 37(5). · 2.74 Impact Factor
  • ASME Gas Turbine India Conference 2012; 12/2012
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    ABSTRACT: 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 and on the economic (fuel burn and engine life) implications from an operator's perspective. Engine component degradation leads to performance deterioration and change, which requires the engine to run hotter and faster so as to meet the required thrust and aircraft performance. Increasing engine operating temperatures and engine speed result in increased creep and fatigue damage to the hot section components and increases the engine life cycle costs. One way of reducing life cycle costs is by better usage of the engine and involves being certain about the life potential of the engine and its components and how this life evolves with use. A sound understanding of how the engine life evolves and to predict remaining life requires understanding the engine's operating environment and how component damage is sustained and accumulated. Knowledge about the engine condition and the likely stresses to which it will be subjected is required to analyse engine component usage and reduce degradation, raise safe-life limits of components and reduce maintenance requirements. This paper lays the foundation for the development of a prognostic tool that will capture and model the mechanisms of degradation, and predict levels of degradation based on engine deployment. The mechanisms that will cause degradation are assessed and integrated to establish the requirements of the tool. The paper discusses how degradation will affect component and engine performance and also the life of the engine.
    ASME 2012 Gas Turbine India Conference; 12/2012
  • ASME Gas Turbine India Conference 2012, Mumbai, India; 12/2012
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    ABSTRACT: Engineering improvements, technology enhancements and advanced operations have an important role to play in reducing aviation fuel consumption and environmental emissions. Currently several organizations worldwide are focusing their efforts towards large collaborative projects whose main objective is to identify the best technologies or routes to reduce the environmental impact and fuel efficiency of aircraft operations. The paper describes the capability of a multi-disciplinary optimization framework named GATAC (Green Aircraft Trajectories under ATM Constrains) developed as part of the Clean Sky project to identify the potential cleaner and quieter aircraft trajectories. The main objective of the framework is to integrate a set of specific models and perform multi-objective optimization of flight trajectories according to predetermined operational and environmental constraints. The models considered for this study include the Aircraft Performance Model, Engine Performance Simulation Model and the Gaseous Emissions Model. The paper, further discusses the results of a test case to demonstrate trade-offs between fuel consumption, flight time and NOx emissions that the trajectory optimization activity achieves at a primary level. It thereby forms the basis of a complete reference base-line trajectory which will be used to determine more accurate environmental gains that can be expected through optimization with the integration of more models within the framework in the future.
    Journal of Aeronautics and Aerospace Engineering. 12/2012; 2(1).
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    Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering 01/2012; 226(2):163-181. · 0.40 Impact Factor
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    ABSTRACT: A challenge in civil aviation future propulsion systems is expected to be the integration with the airframe, coming as a result of increasing bypass ratio or above wing installations for noise mitigation. The resulting highly distorted inlet flows to the engine make a clear demand for advanced gas turbine performance prediction models. Since the dawn of jet engine, several models have been proposed, and the present work comes to add a model that combines two well-established compressor performance methods in order to create a quasi-three-dimensional representation of the fan of a modern turbofan. A streamline curvature model is coupled to a parallel compressor method, covering radial and circumferential directions, respectively. Model testing has shown a close agreement to experimental data, making it a good candidate for assessing the loss of surge margin on a high bypass ratio turbofan, semiembedded on the upper surface of a broad wing airframe.
    International Journal of Rotating Machinery 01/2011; 2011.
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    Journal of Engineering for Gas Turbines and Power 01/2011; 133(1):01170101-01170110. · 0.82 Impact Factor
  • Journal of Engineering for Gas Turbines and Power 01/2011; 133(3):031702. · 0.82 Impact Factor
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    ABSTRACT: This article describes the findings of a study which examined the influence of fouling on the behaviour of a cascade and by making use of these results the performance implications for gas turbine engines of exposure to airborne foulants.
    Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy 11/2010; 224(7):1007-1018. · 0.64 Impact Factor
  • IDGTE, Cranfield, UK; 03/2010