Special Issue "Gas Turbines Propulsion and Power"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (31 January 2017).

Special Issue Editors

Prof. Dr. Pericles Pericles Pilidis
E-Mail
Guest Editor
Centre for Propulsion Engineering, Cranfield University, Bedfordshire MK43 0AL, UK
Interests: gas turbine performance; gas turbines for air, land and sea applications; gas turbine methods; combined cycle gas turbines; power plant integration; TERA (Techno economic Environmental Risk Analysis); power plant asset management
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Dr. Theoklis Nikolaidis
E-Mail Website
Guest Editor
Centre for Propulsion Engineering, Cranfield University, Bedfordshire, UK
Interests: modelling-simulation advanced numerical methods; steady state/transient performance; engine’s control system; variable and novel cycles; particulate/multiphase flows and their effects on engine’s performance; alternative fuels; health monitoring
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Gas turbines engines are extensively used in aviation because of their advantageous volume and weight characteristics. The engines are designed to offer cost-effective features such as high efficiency, reliability and availability. Understanding their aero-thermodynamic performance is a prerequisite for many developments in their cycle, components’ design and maintenance techniques. Modelling and simulating the jet engine at a preliminary design phase is very important for minimizing the development cost and optimizing its performance. This goal calls for new tools and techniques for assessing engine’s performance under a variety of configurations, alternative fuels or/and fluid flows. Variable geometry engines, open rotor and high by-pass turbofan are examples of different configurations, which alter the engine cycle limits. Particulate or multiphase flows such as water droplets and sand particles have an effect on engine’s performance. Understanding engine’s operation at a preliminary design phase is essential for any development.

The Special Issue of the journal Applied Sciences, “Gas turbines propulsion and power”, aims to cover recent advances in the development of modelling and simulating gas turbine performance from the component to the engine level.

Prof. Dr. Pericles Pilidis
Dr. Theoklis Nikolaidis
Guest Editors

Manuscript Submission Information

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Keywords

  • Gas turbine performance
  • Variable geometry engine
  • Open rotor engines
  • Particulate/multiphase flows in gas turbines
  • Turbofan engines
  • Gas turbine cycle

Published Papers (10 papers)

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Research

Article
Multi-Objective Climb Path Optimization for Aircraft/Engine Integration Using Particle Swarm Optimization
Appl. Sci. 2017, 7(5), 469; https://doi.org/10.3390/app7050469 - 30 Apr 2017
Cited by 10 | Viewed by 3442
Abstract
In this article, a new multi-objective approach to the aircraft climb path optimization problem, based on the Particle Swarm Optimization algorithm, is introduced to be used for aircraft–engine integration studies. This considers a combination of a simulation with a traditional Energy approach, which [...] Read more.
In this article, a new multi-objective approach to the aircraft climb path optimization problem, based on the Particle Swarm Optimization algorithm, is introduced to be used for aircraft–engine integration studies. This considers a combination of a simulation with a traditional Energy approach, which incorporates, among others, the use of a proposed path-tracking scheme for guidance in the Altitude–Mach plane. The adoption of population-based solver serves to simplify case setup, allowing for direct interfaces between the optimizer and aircraft/engine performance codes. A two-level optimization scheme is employed and is shown to improve search performance compared to the basic PSO algorithm. The effectiveness of the proposed methodology is demonstrated in a hypothetic engine upgrade scenario for the F-4 aircraft considering the replacement of the aircraft’s J79 engine with the EJ200; a clear advantage of the EJ200-equipped configuration is unveiled, resulting, on average, in 15% faster climbs with 20% less fuel. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Design Point Performance and Optimization of Humid Air Turbine Power Plants
Appl. Sci. 2017, 7(4), 413; https://doi.org/10.3390/app7040413 - 20 Apr 2017
Cited by 10 | Viewed by 2365
Abstract
With the recent drive towards higher thermal efficiencies and lower emission levels in the power generation market, advanced cycle power plants have become an increasingly appealing option. Among these systems, humid air turbines have been previously identified as promising candidates to deliver high [...] Read more.
With the recent drive towards higher thermal efficiencies and lower emission levels in the power generation market, advanced cycle power plants have become an increasingly appealing option. Among these systems, humid air turbines have been previously identified as promising candidates to deliver high efficiency and power output with notably low overall system volume, weight and emissions footprint. This paper investigates the performance of an advanced humid air turbine power cycle and aims to identify the dependencies between key cycle design variables, thermal performance, weight and cost by means of a parametric design optimization approach. Designs of the main heat exchangers are generated, aiming to ascertain the relationship between their technology level and the total weight and acquisition cost of them. The research outcomes show that the recuperator and the intercooler are the two components with the largest influence on the thermal efficiency and the total cost. The total weight of the power system is driven by the technology level of the recuperator and the economizer. Finally, the effectiveness of the aftercooler seems to have the greatest impact in reducing the total acquisition cost of the system with minimum penalty on its thermal efficiency. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Analyses of the Effect of Cycle Inlet Temperature on the Precooler and Plant Efficiency of the Simple and Intercooled Helium Gas Turbine Cycles for Generation IV Nuclear Power Plants
Appl. Sci. 2017, 7(4), 319; https://doi.org/10.3390/app7040319 - 24 Mar 2017
Cited by 10 | Viewed by 2116
Abstract
Nuclear Power Plant (NPP) precooler coolant temperature is critical to performance because it impacts the work required to increase the coolant pressure. Variation of the coolant temperature results in varied precooler hot gas temperatures, which are cooled before re-entry. For recirculation, the heat [...] Read more.
Nuclear Power Plant (NPP) precooler coolant temperature is critical to performance because it impacts the work required to increase the coolant pressure. Variation of the coolant temperature results in varied precooler hot gas temperatures, which are cooled before re-entry. For recirculation, the heat sink (usually sea water), could exit the precooler at unfavourable temperatures and impact the re-entering coolant, if not recirculated properly at the source. The study objective is to analyse the effects of coolant inlet temperature on the heat sink and cycle efficiency. The cycles are Simple Cycle Recuperated (SCR), Intercooler Cycle Recuperated (ICR), and Intercooled Cycle without Recuperation (IC). Results show that the co-current precooler provides favourable outlet heat sink temperatures but compromises compactness. For a similar technology level, the counter-current precooler yields excessive heat sink outlet temperatures due to a compact, robust, and efficient heat transfer design, but could be detrimental to precooler integrity due to corrosion, including the cycle performance, if not recirculated back into the sea effectively. For the counter-current, the ICR has the best heat sink average temperature ratio of 1.4; the SCR has 2.7 and IC has 3.3. The analyses aid the development of Gas Cooled Fast Reactors (GFRs) and Very High Temperature Reactors (VHTRs), where helium is used as the coolant. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Physics of Prestall Propagating Disturbances in Axial Compressors and Their Potential as a Stall Warning Indicator
Appl. Sci. 2017, 7(3), 285; https://doi.org/10.3390/app7030285 - 14 Mar 2017
Cited by 12 | Viewed by 3099
Abstract
Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating [...] Read more.
Axial compressors in aero engines are prone to suffering a breakdown of orderly flow when operating at the peak of the pressure rise characteristic. The damaging potential of separated flows is why a safe distance has to be left between every possible operating point and an operating point at which stall occurs. During earlier investigations of stall inception mechanisms, a new type of prestall instability has been found. In this study, it could be demonstrated that the prestall instability characterised by discrete flow disturbances can be clearly assigned to the subject of “Rotating Instabilities”. Propagating disturbances are responsible for the rise in blade passing irregularity. If the mass flow is reduced successively, the level of irregularity increases until the prestall condition devolves into rotating stall. The primary objective of the current work is to highlight the basic physics behind these prestall disturbances by complementary experimental and numerical investigations. Before reaching the peak of the pressure rise characteristic flow, disturbances appear as small vortex tubes with one end attached to the casing and the other attached to the suction surface of the rotor blade. These vortex structures arise when the entire tip region is affected by blockage and at the same time the critical rotor incidence is not exceeded in this flow regime. Furthermore, a new stall indicator was developed by applying statistical methods to the unsteady pressure signal measured over the rotor blade tips, thus granting a better control of the safety margin. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Development of a Preliminary Design Method for Subsonic Splittered Blades in Highly Loaded Axial-Flow Compressors
Appl. Sci. 2017, 7(3), 283; https://doi.org/10.3390/app7030283 - 14 Mar 2017
Cited by 7 | Viewed by 3483
Abstract
This paper presents a model for predicting the reference minimum-loss incidence and deviation angles of a blade arrangement with splitter vanes, which is probably a solution for future ultra-highly loaded axial compressor designs. The motivation of the modeling is to guide the blading [...] Read more.
This paper presents a model for predicting the reference minimum-loss incidence and deviation angles of a blade arrangement with splitter vanes, which is probably a solution for future ultra-highly loaded axial compressor designs. The motivation of the modeling is to guide the blading design in splittered compressor design processes where the additional splitter vanes must be specially considered. The development of the model is based on a blade performance database from systematic numerical simulations. Basic correlations of the model are firstly proposed, which consider dominant blade geometry parameters related to blade loading, including camber angle and solidity. Secondly, geometric and aerodynamic corrections about orientation parameter, blade maximum thickness, inlet Mach number, and three-dimensional (3D) effects are empirically incorporated into the basic correlations. Eventually, a subsonic 3D splittered rotor is designed using the correlations coupled with the corrections obtained from the validation of the model. The results indicate that the model is able to achieve a good agreement within an error band of ±1.0° for the predictions of both reference minimum-loss incidence and deviation angles, and the rotor designed using the model accomplishes the desired work input and flow deflection. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Coupled Effect of Expansion Ratio and Blade Loading on the Aerodynamics of a High-Pressure Gas Turbine
Appl. Sci. 2017, 7(3), 259; https://doi.org/10.3390/app7030259 - 07 Mar 2017
Cited by 12 | Viewed by 2349
Abstract
The need of a continuous improvement in gas turbine efficiency for propulsion and power generation, as well as the more demanding operating conditions and power control required to these machines, still ask for great efforts in the design and analysis of the high [...] Read more.
The need of a continuous improvement in gas turbine efficiency for propulsion and power generation, as well as the more demanding operating conditions and power control required to these machines, still ask for great efforts in the design and analysis of the high pressure section of the turbo-expander. To get detailed insights and improve the comprehension of the flow physics, a wide experimental campaign has been performed in the last ten years at Politecnico di Milano on the unsteady aerodynamics of a high-pressure turbine stage considering several operating conditions. This paper presents and discusses the experimental results obtained for the stage operating with different expansion ratios and rotor loading. The turbine stage under study is representative of a modern high-pressure turbine and can be operated in both subsonic and transonic conditions. The experimental tools applied for the current research represents the state of the art when unsteady investigations are foreseen. The detailed flow field, the blade–rows interaction and the overall performance are described and discussed; efforts have been devoted to the discussion of the various contribution to the overall stage efficiency. The direct effects of the expansion ratio, affecting the Reynolds and the Mach numbers, have been highlighted and quantified; similarly, the indirect effects, accounting for a change in the rotor loading, have been commented and quantified as well, thanks to a dedicated set of experiments where different rotor loadings at the same expansion ratio have been prescribed. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Performance of a Supercritical CO2 Bottoming Cycle for Aero Applications
Appl. Sci. 2017, 7(3), 255; https://doi.org/10.3390/app7030255 - 06 Mar 2017
Cited by 18 | Viewed by 3234
Abstract
By 2050, the evolutionary approach to aero engine research may no longer provide meaningful returns on investment, whereas more radical approaches to improving thermal efficiency and reducing emissions might still prove cost effective. One such radical concept is the addition of a secondary [...] Read more.
By 2050, the evolutionary approach to aero engine research may no longer provide meaningful returns on investment, whereas more radical approaches to improving thermal efficiency and reducing emissions might still prove cost effective. One such radical concept is the addition of a secondary power cycle that utilizes the otherwise largely wasted residual heat in the core engine’s exhaust gases. This could provide additional shaft power. Supercritical carbon dioxide closed-circuit power cycles are currently being investigated primarily for stationary power applications, but their high power density and efficiency, even for modest peak cycle temperatures, makes them credible bottoming cycle options for aero engine applications. Through individual geometric design and performance studies for each of the bottoming cycle’s major components, it was determined that a simple combined cycle aero engine could offer a 1.9% mission fuel burn benefit over a state-of-the-art geared turbofan for the year 2050. However, the even greater potential of more complex systems demands further investigation. For example, adding inter-turbine reheat (ITR) to the combined cycle is predicted to significantly improve the fuel burn benefit. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Effect of Slot at Blade Root on Compressor Cascade Performance under Different Aerodynamic Parameters
Appl. Sci. 2016, 6(12), 421; https://doi.org/10.3390/app6120421 - 10 Dec 2016
Cited by 25 | Viewed by 2981
Abstract
The effects of compressor aerodynamic parameters, such as pitch-chord ratio, aspect ratio, and fillet, on the cascade performance have been studied in this paper. Slot configuration at the root of the blade has been proved to be an efficient passive control method for [...] Read more.
The effects of compressor aerodynamic parameters, such as pitch-chord ratio, aspect ratio, and fillet, on the cascade performance have been studied in this paper. Slot configuration at the root of the blade has been proved to be an efficient passive control method for the corner separation control in compressor cascade. The combined effects of the pitch-chord ratio, aspect ratio, and blade fillet with a slot configuration on the blade, have also been studied. Larger corner separation caused by the high pitch-chord ratio can be eliminated by the slot, which leads to fewer blades with almost the same or even better cascade performance. Various aspect ratios, together with the slot configuration, have been investigated and all of them have a positive effect on the cascade performance. For the blade with the blade fillet, the slot still has a positive effect on the control of the corner separation, while cascade performance with just a slot configuration is better than the slot configuration under the influence of the blade fillet. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
Axial Turbine Cascade Correlation
Appl. Sci. 2016, 6(12), 420; https://doi.org/10.3390/app6120420 - 10 Dec 2016
Cited by 1 | Viewed by 2419
Abstract
The performance simulation of an axial turbine is achieved in a simple way from the calculation of velocity diagrams. For this purpose, a reliable loss model is needed for the flow through each stationary or rotating axial blade cascade. A loss coefficient assessment [...] Read more.
The performance simulation of an axial turbine is achieved in a simple way from the calculation of velocity diagrams. For this purpose, a reliable loss model is needed for the flow through each stationary or rotating axial blade cascade. A loss coefficient assessment is conducted through the establishment of a correlation between the maximum profile velocity ratio and a circulation parameter, dedicated specifically to turbine cascades. A detailed examination of published wind tunnel cascade tests available in the literature provides enough experimental data to support the proposed correlation. Afterwards, the surface diffusion is quantified and the total pressure loss estimation is obtained from the boundary layer momentum thickness and conservation equations for the downstream flow. Further validation of the proposed loss model is presented from published experimental results in turbine cascades and stages. The simulation methodology is also demonstrated in two single-stage steam turbine units applied to the oil refining industry, in comparison with performance factory tests results. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Article
A Study on Combined Variable Geometries Regulation of Adaptive Cycle Engine during Throttling
Appl. Sci. 2016, 6(12), 374; https://doi.org/10.3390/app6120374 - 25 Nov 2016
Cited by 27 | Viewed by 2306
Abstract
The most remarkable variable cycle characteristic of the variable cycle engine (VCE) is that it keeps airflow almost constant during subsonic cruise throttling by modulating variable geometries, which can efficiently decrease spillage drag and increase installed thrust. One of the most critical challenges [...] Read more.
The most remarkable variable cycle characteristic of the variable cycle engine (VCE) is that it keeps airflow almost constant during subsonic cruise throttling by modulating variable geometries, which can efficiently decrease spillage drag and increase installed thrust. One of the most critical challenges for the modulation lies in completely maintaining airflow, as well as avoiding specific fuel consumption (SFC) degradation during throttling. This has resulted in a need to investigate the modulation regulation of the adaptive cycle engine (ACE) which is a new concept for VCE and has greater potential for flexibly modulating airflow and pressure ratio. Thus, the aim of this paper is to study the variable geometries’ modulation schedule of ACE in maintaining airflow during throttling. A configuration of an ACE concept and its modeling study are first put forward. Then, the control schedule is researched via the combination of sensibility analysis and basic working principle instead of optimizing them directly. Results show that when the net thrust decreases from 100% to about 55% during subsonic cruise and to 32% during the supersonic cruise, the demand airflow of the engine is kept almost constant, which greatly improves the installed performance during throttling. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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