Browsing by Author "Mourouzidis, Christos"
Now showing 1 - 16 of 16
Results Per Page
Sort Options
Item Open Access Abating CO2 and non-CO2 emissions with hydrogen propulsion(Cambridge University Press (CUP), 2024-04-02) Mourouzidis, Christos; Singh, G.; Sun, X.; Huete, Jon; Nalianda, Devaiah; Nikolaidis, Theoklis; Sethi, Vishal; Rolt, Andrew Martin; Goodger, E.; Pilidis, PericlesThis contribution focuses on the abatement with hydrogen of CO2 and non-CO2 emissions. It is agenda-setting in two respects. Firstly, it challenges the globally accepted hydrocarbon sustainable aviation fuel (SAF) pathway to sustainability and recommends that our industry accelerates along the hydrogen pathway to ‘green’ aviation. Secondly, it reports a philosophical and analytical investigation of appropriate accuracy on abatement strategies for nitrogen oxides and contrails of large hydrogen airliners. For the second contribution, a comparison is made of nitrogen oxide emissions and contrail avoidance options of two hydrogen airliners and a conventional airliner of similar passenger capacity. The hydrogen aircraft are representative of the first and second innovation waves where the main difference is the weight of the hydrogen tanks. Flights of 1000, 2000, 4000 and 8000 nautical miles are explored. Cranfield’s state of the art simulators for propulsion system integration and gas turbine performance (Orion and Turbomatch) were used for this. There are two primary contributions to knowledge. The first is a new set of questions to be asked of SAF and hydrogen decarbonising features. The second is the quantification of the benefits from hydrogen on non-CO2 emissions. For the second generation of long-range hydrogen-fuelled aircraft having gas turbine propulsion, lighter tanks (needing less thrust and lower gas temperatures) are anticipated to reduce NOx emissions by over 20%; in the case of contrails, the preliminary findings indicate that regardless of the fuel, contrails could largely be avoided with fuel-burn penalties of a few per cent. Mitigating action is only needed for a small fraction of flights. For conventional aircraft this penalty results in more CO2, while for hydrogen aircraft the additional emission is water vapour. The conclusion is that our research community should continue to consider hydrogen as the key ‘greening’ option for aviation, notwithstanding the very significant costs of transition.Item Open Access Ammonia for civil aviation: a design and performance study for aircraft and turbofan engine(Elsevier, 2024-04-06) Sasi, Sarath; Mourouzidis, Christos; Rajendran, David John; Roumeliotis, Ioannis; Pachidis, Vassilios; Norman, JustinThe 2050 net zero targets for aviation to decarbonize the industry means that solutions need to be delivered that can help achieve those targets. Transitioning to zero carbon aviation fuel is an effective solution to achieve those targets. This research article aims to highlight the potential design and performance implications of using Ammonia as a zero-carbon fuel for civil aviation through a retrofit case study conducted for an Airbus A350-1000 equivalent aircraft. The impacts on both turbofan design and aircraft payload-range capability are presented. A feasibility study of using Ammonia as a Hydrogen carrier for civil aviation is also presented. The turbofan design impacts, and payload range capability are assessed using Cranfield University’s in-house gas turbine performance tool TURBOMATCH and NASA FLOPS respectively. A 3-point turbofan cycle design strategy is utilized for redesigning turbofan engine cycles using Ammonia as a fuel. Ammonia fuel conditioning assessment is made using REFPROP to investigate its impact on turbofan design. Utilizing pure Ammonia as an aircraft fuel can provide significant turbofan redesign opportunities. Fuel conditioning assessment revealed that for a 430 kN thrust class engine, 2.1 MW of thermal power is required to condition Ammonia fuel at take-off. As a result, various strategies to condition the fuel and its significant impact on turbofan design are presented indicating fuel conditioning as a major design driver for Ammonia fuelled turbofan engines in the future. Although upon initial preliminary assessment, Ammonia utilized as a Hydrogen carrier showcased potential by providing additional mission range capability when compared to a pure Ammonia burning aircraft, the significant thermal energy required to crack (decompose) Ammonia into Hydrogen highlighted the challenges at aircraft mission level and Hydrogen turbofan design implications. It is found that energy requirement (power) to crack Ammonia into Hydrogen are significant which is approximately an order of magnitude higher than Ammonia fuel conditioning itself.Item Open Access Assessing uninstalled hydrogen-fuelled retrofitted turbofan engine performance(MDPI, 2025-03-12) Farabi, Jarief; Mourouzidis, Christos; Pilidis, PericlesHydrogen as fuel in civil aviation gas turbines is promising due to its no-carbon content and higher net specific energy. For an entry-level market and cost-saving strategy, it is advisable to consider reusing existing engine components whenever possible and retrofitting existing engines with hydrogen. Feasible strategies of retrofitting state-of-the-art Jet A-1 fuelled turbofan engines with hydrogen while applying minimum changes to hardware are considered in the present study. The findings demonstrate that hydrogen retrofitted engines can deliver advantages in terms of core temperature levels and efficiency. However, the engine operability assessment showed that retrofitting with minimum changes leads to a ~5% increase in the HP spool rotational speed for the same thrust at take-off, which poses an issue in terms of certification for the HP spool rotational speed overspeed margin.Item Open Access Assessment of a liquid hydrogen conditioning system for retrofitting on kerosene designed turbofans(ASME , 2025-10-01) Rompokos, Pavlos; Kyritsis, Vasileios; Mourouzidis, Christos; Roumeliotis, IoannisAs energy transition to alternative fuels for civil aviation is likely to be gradual, hydrogen’s first entry to service may be implemented on existing gas turbine engines. In this paper a novel liquid hydrogen conditioning system for retrofitting on kerosene designed geared turbofans is assessed in terms of performance and engine rematching. The aim of the analysis is to identify emerging requirements for the design of the fuel and thermal management system within the constraints of a certified engine design. The conditioning system proposed, an LH2 preheater, enables the control of the gaseous hydrogen temperature at combustor entry and consists of a secondary combustor and a heat exchanger. The examined configuration considers various bleed source locations within the engine to supply the preheater system. For performing the analysis, a kerosene fueled engine has been designed and suitable integrated models capable to simulate the retrofitted hydrogen fueled engine as well as the LH2 preheater operation have been developed. The system performance has been analyzed for the different bleed source locations identifying operating limits and performance changes. From all the examined bleed source positions, utilizing the by-pass duct minimizes the impact on component rematching and engine efficiency. Additionally, through a gas path geometry multiparametric analysis, it was found that by readjusting the capacity of the high-pressure turbine and the core nozzle area the certified limits can be met for the retrofitted engine.Item Open Access Assessment of performance boundaries and operability of low specific thrust GUHBPR engines for EIS2025(American Society of Mechanical Engineers, 2022-04-25) Mo, Da; Roumeliotis, Ioannis; Mourouzidis, Christos; Kissoon, Sajal; Liu, YixiongThis paper aims to develop a robust design process by approaching the performance boundaries and evaluating the operability of the pursued geared turbofan engine with low specific thrust for EIS 2025. A two-spool direct-drive turbofan (DDTF) engine of EIS 2000 was improved according to aircraft specifications and technology boundaries in 2025. A series of optimized engines with consecutive fan diameters were established to seek the ideal engine by balancing SFC, weight and mission fuel burn. The fan diameter was proved to be a decisive factor for lowering SFC and energy usage. The cycle design optimization process achieved a thermal efficiency of approximately 52%, and a propulsive efficiency of 79.5%, which is 8.19% increase in propulsive efficiency by enlarging fan diameter from 1.6m to 1.9m. Meanwhile, the 1.9m-fan diameter engine achieved a reduction in SFC and fuel burn of 7.47% and 6.58% respectively which offers an overall reduction of 30.82% in block fuel burnt and CO2 emission compared to the DDTF engine. A feasibility check verified the viability of the designed optimum engine in terms of fan tip speed, stage loading and AN2. Dynamic simulation offered a deep understanding of transient behaviour and fundamental mechanism of the geared turbofan engine. An important aspect of this paper is the use of advanced CMC materials, which led to an improvement of 4.92% in block fuel burn and 2.93% in engine weight.Item Open Access Assessment of the performance boundaries of very low specific thrust direct-drive turbofan engines at aircraft level for EIS 2025(GPPS Chania20, 2020-09-07) Kissoon, Sajal; Zhang, Fan; Mourouzidis, Christos; Roumeliotis, Ioannis; Pachidis, VassiliosWithin the past decade, concerns over the environmental impact of civil aviation have pushed the research community towards the development of more efficient propulsion technology, which delivers a lower carbon and NOx footprint. The current progress achieved in the various specialised disciplines creates the need to redefine the performance barrier achievable by 2025 state-of-the-art aero-engines. This paper summarises some of the latest advancements within the gas turbine research community on the performance modelling and analysis of very low dspecific thrust direct-drive turbofan engines for EIS 2025. Engine and aircraft performance models were used to predict the extent of fuel burn reduction at aircraft level that could be achieved by reducing the engine specific thrust level , increasing operating pressure and temperature levels and applying technology factors representing a step beyond current state-of-the-art. The models represented modern three-spool direct-drive turbofans powering a typical A350XWB-type aircraft. The outputs of the engine design of experiments (DoE) exercise resulted in three most promising candidates. Targeting EIS in 2025, the final optimum design showed 14.81% block fuel improvement for a representative long (7000nm) range mission, accompanied by 30.9% penalty on engine weight. These results propose that with current technology level, at the lower end of the specific thrust range, there is still available design space for the direct-drive turbofan architectureItem Open Access Assessment of thermo-electric power plants for rotorcraft application(ASME, 2019-10-01) Roumeliotis, Ioannis; Mourouzidis, Christos; Zafferetti, Mirko; Deniz, Unlu; Broca, Olivier; Pachidis, VassiliosThis paper assesses a parallel electric hybrid propulsion system utilizing simple and recuperated cycle gas turbine configurations. An adapted engine model capable to reproduce a turboshaft engine steady state and transient operation is built in Simcenter Amesim and used as a baseline for a recuperated engine. The transient operation of the recuperated engine is assessed for different values of heat exchanger effectiveness, quantifying the engine lag and the surge margin reduction which are results of the heat exchanger addition. An oil and gas mission of a twin engine medium helicopter has been used for assessing the parallel hybrid configuration. The thermo-electric system brings a certain level of flexibility allowing for better engine utilization, thus firstly a hybrid configuration based on simple cycle gas turbine scaled down from the baseline engine is assessed in terms of performance and weight. Following the recuperated engine thermo-electric power plant is assessed and the performance enhancement is compared against the simple cycle conventional and hybrid configurations. The results indicate that a recuperated gas turbine based thermo - electric power plant may provide significant fuel economy despite the increased weight. At the same time the electric power train can be used to compensate for the reduced specific power and potentially for the throttle response change due to the heat exchanger addition.Item Open Access Design methodology and mission assessment of parallel hybrid electric propulsion systems(American Society of Mechanical Engineers, 2022-09-16) Ghelani, Raj; Roumeliotis, Ioannis; Saias, Chana Anna; Mourouzidis, Christos; Pachidis, Vassilios; Norman, Justin; Bacic, MarkoAn integrated engine cycle design methodology and mission assessment for parallel hybrid electric propulsion architectures are presented in this paper. The aircraft case study considered is inspired by Fokker 100, boosted by an electric motor on the low-pressure shaft of the gas turbine. The fuel burn benefits arising from boosting the low-pressure shaft are discussed for two different baseline engine technologies. A three-point engine cycle design method is developed to redesign the engine cycle according to the degree of hybridization. The integrated cycle design and power management optimization method is employed to identify potential fuel burn benefits from hybridization for multiple mission ranges. The sensitivity of these mission results has also been analyzed for different assumptions on the electric powertrain. With 1 MW motor power and a battery pack of 2307 kg, a 3% fuel burn benefit can be obtained by retrofitting the gas turbine for 400 nm range. Optimizing the power management strategy improves this fuel burn benefit by 0.2-0.3%. Redesigning the gas turbine and optimizing the power management strategy, provides a 4.2% fuel benefit on 400 nm. The results suggest that a high hybridization by power, low hybridization by energy, and ranges below 700 nm are the only cases where the redesigned hybrid electric aircraft has benefits in fuel burn and energy consumption relative to the baseline aircraft. Finally, it is found that the percentage of fuel burn benefits from the hybrid electric configuration increases with the improvement in engine technology.Item Open Access Dynamic simulation and aircraft level assessment of CMC implementation on GTF engine(Springer, 2022-12-16) Mo, Da; Roumeliotis, Ioannis; Liu, Yixiong; Mourouzidis, Christos; Kissoon, SajalThis paper dynamically simulated the geared turbofan engine with CMC turbine components, including impacts of fuel schedule, shaft inertia, volume packing, BOV schedule. Deliberated comparisons were performed between CMC engine and Inconel engine on aircraft level performance and transient behaviour. Heat load examination is included in flight mission analysis, which lays the basis on the gearbox efficiency map related to torque and rotational speed. Results indicate that IPC surge margin of the CMC case slightly fall 0.15% but maintain steady. The mitigated T4 overshooting phenomenon has offered a 30 K drop and thus extended turbine life. More importantly, Fan shaft inertia dominantly affects engine operability, whereas the blow-off air fraction severely impacts the low power setting operation. Further investigation of heat load reveals that power loss at take-off segment accounts for 1.1% of IP shaft input power, which is 3.98% higher than Inconel case. The thermal management system needs to be redesigned to absorb extra heat. On assessment of aircraft level performance, CMC engine provides superior profits in maximizing airline revenue. The predicted annual fuel cost saving is about 0.08 million dollars coming from block fuel reduction. NOx, noise and CO2 demonstrate obvious decline, approaching 5.9%, 1.0% and 4.9%, respectively.Item Open Access Evaluation of a collaborative and distributed aircraft design environment, enabled by microservices and cloud computing(AIAA, 2023-01-19) Chen, Xin; Isoldi, Adriano; Riaz, Atif; Mourouzidis, Christos; Keskin, Akin; Smith, Dale; Guenov, Marin D.; Pachidis, VassiliosPresented in this paper are the outcomes from the evaluation of a distributed aircraft design environment, based on microservices and cloud computing. The evaluation was performed on a representative airframe-engine optimization case study, including the engine, wing aero-structural geometry, and high-lift devices. The (computational) design process involved multiple distributed design teams and design tools. The latter were implemented with different programming languages and deployed on the Azure cloud service. As a benchmark, the same case study was performed using the traditional email/document-based approach to design collaboration. Compared with the traditional collaboration, the cloud-based approach substantially reduced the time for design iterations between the design teams. This was mainly due to the fast remote access of models/tools on the cloud and automation of data exchange. Also, the exercise indicated that the cloud-based approach is more flexible with regard to orchestrating the computational workflows and optimization studies, while protecting the Intellectual Property (IP) of the collaborating partners.Item Open Access Impacts of alternative aviation fuels on engine cycle design and aircraft mission capability(American Society of Mechanical Engineers, 2023-09-28) Sasi, Sarath; Mourouzidis, Christos; Roumeliotis, Ioannis; Nikolaidis, Theoklis; Pachidis, Vassilios; Norman, JustinRecent 2050 net zero targets for aviation have sparked interest among the industry players to seek alternative aviation fuels as a pathway for the immediate alleviation of its carbon footprint. This paper aims to shed light on the opportunities and challenges that zero & low-carbon alternative fuels can provide from a technical standpoint. To address this aim, candidate fuels for aviation were selected from five broad classes of fuels. Then, a preliminary thermodynamic engine cycle design space exploration of a modern three spool turbofan is conducted to identify the fuel impact on cycle performance. Following that, an integrated Engine-Aircraft mission assessment for a Boeing 787 style aircraft with a three spool turbofan is conducted to assess performance at the mission level and explore opportunities and challenges for both powerplant and aircraft, accounting for fuel storage. Finally, an investigation of the opportunities available for the proposed fuels to be used as a heat sink is presented. The results indicate that zero-carbon fuels expand the design space for the powerplant cycle, allow for higher BPR, lower energy specific fuel consumption, lower peak cycle temperatures compared to the rest of the fuels, and provide significant cycle redesign opportunities. On a mission level, cryogenic fuels are penalized for block energy consumption due to the significant weight and size of the fuel storage system, while liquid alternative fuels are comparable to kerosene in terms of emissions and block energy consumption. Concerning Hydrogen, Methane, and Ammonia, the thermal power requirement for fuel conditioning (pressure and temperature rise) is calculated to be 2.2MW, 1.3MW, and 1MW respectively for a 240kN SLS thrust class engine during take-off.Item Open Access Installation effects of supersonic inlets on next-generation SST turbofan engines(MDPI, 2025-03-14) Adamidis, Stylianos; Del Gatto, Dario; Mourouzidis, Christos; Brown, Stephen; Pachidis, VassiliosThis study explores inlet-related installation effects on next-generation SST aircraft, focusing on supersonic business jets. Using a comprehensive framework with consistent thrust/drag bookkeeping and realistic modeling of inlet losses, including operational limits for “buzz” and distortions, the inlet drag accounts for 8.8% to 14.2% of the installed net thrust during the supersonic segment of the mission. Variable airflow control technology is assessed, with a scheduling methodology developed to optimize the inlet operation by minimizing the installed SFC. The results show that this technology improves the installed SFC by 0.80% during supersonic cruise, enhancing the overall propulsion system performance.Item Embargo Integrated assessment of parallel hybrid electric aircraft propulsion architectures(Cranfield University, 2023-10) Ghelani, Raj; Roumeliotis, Ioannis; Pachidis, Vassilios; Mourouzidis, Christos; Bacic, Marko; Norman, JustinAdvisory Council for Aeronautical Research in Europe (ACARE) has published ambitious goals for reduction in emissions from aircraft applications by the year 2050. Hybrid-electric and alternative fuelled powerplants have been proposed as one of the major solutions to resolve this problem. There has been significant industrial push to build and test viable hybrid-electric propulsion systems onboard aircraft and certify them for flight, with Rolls-Royce ACCEL, Airbus E-Fan X and Boeing SUGAR VOLT being some recent examples. Despite this, there exists significant uncertainty around the potential fuel burn benefits from these architectures across the different aircraft classes, the impact on gas turbine design, thermal management and aircraft integration, as well as fleet technology penetration. The work in open literature has focussed on individual aspects mentioned above but no study was found considering all these aspects in a common design and optimization loop. The aim of this thesis is to develop robust integrated design and optimization methods, to help industry examine future application scenarios in a more objective, systematic and therefore, more cost-effective manner. The regional to single aircraft design space is explored with ATR 72, Fokker 100 and A320 being the baseline aircraft platforms. Initially, a design space exploration is performed for the Fokker 100 style airframe utilizing lithium ion batteries in a parallel hybrid configuration. The impact of hybrid gas turbine cycle redesign strategies are benchmarked and compared to retrofit hybrid gas turbine. A power management optimization loop is set up to optimize the power split for varying battery pack sizes and motor powers on different mission ranges. This sweep is also performed for varying technology levels on gas turbine, motor power density and battery energy density. It is demonstrated that the benefit from electrification improves with improvement in gas turbine technology level. The integrated hybrid gas turbine cycle design and power management optimization ANN method is applied to all three aircraft platforms for EIS 2035 time frame. The optimal power management strategies favour take-off and initial climb for redesigned gas turbines while they favour cruise for retrofit gas turbines. Incorporation of direct operating cost modules show retrofit hybrid systems having a lower direct operating cost as compared to redesigned hybrid systems owing to reduced gas turbine maintenance cost. The multi-mission method is applied to the test cases showing the penalty paid in carrying a fixed battery pack. Two thermal management architectures, ram air-liquid coolant heat exchanger and vapour compression cycles are utilized to reject the heat load from the electrical systems. The design space of both the systems are first explored for varying levels on quantity of heat load, quality of heat load and flight mission conditions. The method to integrate optimal combinations of thermal management architectures in terms of, coolant mass flow rate, condenser pinch, condenser geometry and compressor pressure ratio is utilized and applied to different propulsion configurations. The full framework is also expanded to include proton exchange membrane fuel cells and hydrogen-powered gas turbines. A final technological assessment is performed for the regional ATR 72 style aircraft platform for both thermal management architectures. A pure electric, battery and fuel cell powered aircraft with an optimal power split is identified as a suitable candidate against kerosene and hydrogen powered gas turbines to power EIS 2035 regional turboprop. While for single-aisle applications, there is a case for mild hybridization to reduce NOx and improve gas turbine operability at part load settings.Item Open Access Integrated hybrid engine cycle design and power management optimization(American Society of Mechanical Engineers, 2023-09-28) Ghelani, Raj; Roumeliotis, Ioannis; Saias, Chana Anna; Mourouzidis, Christos; Pachidis, Vassilios; Bacic, Marko; Norman, JustinA novel integrated gas turbine cycle design and power management optimization methodology for parallel hybrid electric propulsion architectures is presented in this paper. The gas turbine multi-point cycle design method is extended to turboprop and turbofan architectures, and several trade studies are performed initially at the cycle level. It is shown that the maximum degree of electrification is limited by the surge margin levels of the booster in the turbofan configuration. An aircraft mission-level assessment is then performed using the integrated optimization method initially for an A320 Neo style aircraft case. The results indicate that the optimal cycle redesigned hybrid electric propulsion system (HEPS) favors take-off and climb power on-takes while optimal retrofit HEPS favor cruise power on-takes. It is shown that for current battery energy density (250 Wh/Kg), there is no fuel burn benefit. Furthermore, even for optimistic energy density values (750 Wh/kg) the maximum fuel burn benefit for a 500 nm mission is 5.5% and 4% for redesigned and retrofit HEPS, respectively. The power management strategies for HEPS configurations also differ based on gas turbine technology with improvement in gas turbine technology showing greater scope for electrification. The method is then extended to ATR 72 style aircraft case, showing greater fuel burn benefits across the flight mission envelope. The power management strategies also change depending on the objective function, and optimum strategies are reported for direct operating cost or fuel burn. The retrofit case studies show a benefit in direct operating cost compared to redesigned case studies for ATR 72. Finally, a novel multimission approach is shown to highlight the overall fuel burn and direct operating cost benefit across the aircraft mission cluster.Item Open Access Preliminary design of next generation Mach 1.6 supersonic business jets to investigate landing & take-off (LTO) noise and emissions–SENECA(IOP Publishing, 2023-06-28) Mourouzidis, Christos; Del Gatto, Dario; Adamidis, Stylianos; Villena Muñoz, Cristina; Lawson, Craig;; Martinez Corzo, B.; Leyland, P.; Marsh, D.; Lim, L.; Owen, B.With the approach of next generation supersonic transport entry into service, new research activities were initiated to support updates on ICAO regulations and certification processes for supersonic transport vehicles. Within this context, the EU Horizon 2020 SENECA project has been launched to investigate the levels of noise and gaseous emissions in the vicinity of airports as well as the global climate impact of next generation supersonic civil aircraft. This paper introduces some of the preliminary outcomes of this investigation. It presents the preliminary design and performance analysis of a Mach 1.6 business jet, following an integrated aircraft-engine design approach. The preliminary design was performed accounting for the limitations posed by future environmental restrictions on respective subsonic vehicles. The market space and mission route definition exercise assumed only "over-sea" supersonic operations, while for "over-land", only subsonic operations where allowed. Parametric studies on engine integrated design demonstrated modest core temperatures while cruising and the significant impact of engine installation on performance. At this first design iteration, assuming current state of the art technology, the Mach 1.6 business jet showed good potential to satisfy the predicted mission requirements while respecting the environmental constraints in terms of Landing & Take-Off (LTO) noise and emissions.Item Open Access Water injection on aircraft engines: a performance, emissions and economic study(ISABE, 2015-10-22) Mourouzidis, Christos; Igie, Uyioghosa; Pilidis, Pericles; Singh, RitiAlthough 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 Center in collaboration with Boeing Company. The aim of this study is to investigate the performance, emissions and economic aspects of water ingestion for medium and high bypass ratio jet engines using Cranfield University in-house gas turbine simulation software. British Airways was chosen as a representative airline to be used as case study in order to examine the effects of this technology. Performance and emissions models were developed for the most popular aircraft of the fleet, along with their engines. The simulations were focused on the take-off phase of the aircraft, injecting water in the low pressure compressor (LPC) and the combustor, for different water-toair ratios. The results were optimized in terms of fuel burn and verified against the respective results from the NASA study [1]. Finally, an economic model was developed in order to evaluate the monetary impact of these systems, from the point of view of an airliner with a specific number of aircraft in their fleet. The main outcomes of this study show that LPC water injection can provide more than 10% take-off thrust augmentation in a standard day when in hot days it can exceed 25%. Alternatively, the specific fuel consumption at take-off can reach a 10% reduction, for a fixed take-off thrust level. On the other hand, combustor water injection penalizes the engine performance in all cases. Additionally, depending on the point of injection and the water to air ratio, NOx emissions reduction ranges between 25%-85%. Finally, for the case study examined here, the value for the annual monetary benefit due to water injection can reach 599,654£, without taking into account the airport emission based fees. An investment of such sort could present a dynamic payback period of 7.5 years, assuming constant market interest of 8% and 10 years operational life of the equipment.