Browsing by Author "Ortiz Carretero, Jesus"

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    Impact of adverse environmental conditions on rotorcraft operational performance and pollutant emissions
    (ASME, 2017-08-23) Ortiz Carretero, Jesus; Castillo Pardo, Alejandro; Goulos, Ioannis; Pachidis, Vassilios
    It is anticipated that the contribution of rotorcraft activities to the environmental impact of civil aviation will increase in the future. Due to their versatility and robustness, helicopters are often operated in harsh environments with extreme ambient conditions. These severe conditions not only affect the performance of the engine but also affect the aerodynamics of the rotorcraft. This impact is reflected in the fuel burn and pollutants emitted by the rotorcraft during a mission. The aim of this paper is to introduce an exhaustive methodology to quantify the influence adverse environment conditions have in the mission fuel consumption and the associated emissions of nitrogen oxides (NOx). An emergency medical service (EMS) and a search and rescue (SAR) mission are used as case studies to simulate the effects of extreme temperatures, high altitude, and compressor degradation on a representative twin-engine medium (TEM) weight helicopter, the Sikorsky UH-60A Black Hawk. A simulation tool for helicopter mission performance analysis developed and validated at Cranfield University was employed. This software comprises different modules that enable the analysis of helicopter flight dynamics, powerplant performance, and exhaust emissions over a user-defined flight path profile. For the validation of the models implemented, extensive comparisons with experimental data are presented throughout for rotorcraft and engine performance as well as NOx emissions. Reductions as high as 12% and 40% in mission fuel and NOx emissions, respectively, were observed for the “high and cold” scenario simulated at the SAR role relative to the same mission trajectory under standard conditions.
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    The impact of clean sky technology on future 3500 lb single engine light rotorcraft
    (ISABE, 2017-09-08) Enconniere, Julien; Ortiz Carretero, Jesus; Goulos, Ioannis; Pachidis, Vassilios; Smith, C.; Stevens, J.; d'Ippolito, R.; Thevenot, Laurent
    This manuscript describes a collaborative research effort between members of the Clean Sky Joint Technology Initiative (JTI), within the broader area of novel rotorcraft engine technology and rotorcraft operations. The Clean Sky JTI was created as a public/private partnership between the European Commission and the aeronautical industry. The paper assesses the impact of innovative engine technologies to be integrated into the next generation of rotorcraft and evaluates their potential towards meeting the ACARE 2020 goals. The focus is on the lower segment of the light helicopter class with a particular interest in the performance of two innovative powerplants: an advanced turboshaft with Lean Premixed Prevaporised (LPP) combustor design and a supercharged diesel cycle engine. In order to evaluate their benefits alongside other Clean Sky technologies, a multi-disciplinary rotorcraft performance analysis framework (PhoeniX) is employed. Two variants of the same light helicopter platform with year 2020 technology plus Clean Sky innovations are modelled, named hereafter as Single Engine Light (SEL) Y2020 and High Compression Engine (HCE) Y2020, respectively. A turboshaft engine-powered helicopter, representative of year 2000 technology (SEL Y2000) is also modelled and used as reference. Payload-Range diagrams (PR) of the three vehicles were generated. The HCE Y2020 reached a maximum range 83% greater than the SEL counterparts. The gaseous emissions of the helicopters were also evaluated over three notional scenarios representative of light helicopter activities. The HCE Y2020 emitted 60% less carbon dioxide (CO2) and 63% less nitrogen oxides (NOx) than the SEL Y2000. The SEL Y2020 emitted on average 19% and 49% less CO2 and NOx, respectively, compared with the SEL Y2000. It was also observed that the NOx production rate of the LPP technology integrated in the SEL Y2020 combustor depends strongly on engine power setting. At certain power settings, the SEL Y2020 emitted less NOx than the HCE Y2020 even though the HCE Y2020 emitted less NOx over the complete mission. The direct comparison between SEL Y2020 and HCE Y2020 highlighted the superior performance of the HCE engine over the gas turbine for the mission types and rotorcraft class simulated.
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    Mission performance analysis of a conceptual coaxial rotorcraft for air taxi applications
    (Elsevier, 2017-06-15) Enconniere, Julien; Ortiz Carretero, Jesus; Pachidis, Vassilios
    The rotorcraft industry has recently shown a new interest in compound rotorcraft as a feasible alternative to tackle the rapid growth of civil aviation activities and associated environmental impact. Indeed, aircraft contribution to the global emissions of CO2CO2, NOxNOx, and noise are driving the development of innovative technologies and vehicles. At present, compound rotorcraft architectures are regarded by the industry as promising platforms that can potentially increase productivity at a reduced environmental cost. In order to quantify the benefits of compound rotorcraft, this paper details the performance analysis of a coaxial counter-rotating rotor configuration with a pusher propeller. A comprehensive approach targeting the assessment of the aforementioned rotorcraft design for civil applications is presented herein. The methodology developed encompasses a rotorcraft flight dynamics simulation module and an engine performance module, coupled with a gaseous emissions prediction tool for environmental impact studies. They have been integrated together to constitute a standalone performance simulation framework and verified with the performance calculations of Harrington's “rotor 1” and the Sikorsky X2TD. The method is then applied to evaluate the performance of a conceptual coaxial rotorcraft, during a notional inter-city air taxi mission, in terms of cruise altitude, speed, and range, overall mission time and environmental impact. The several trade-offs between these parameters highlight the need for an integrated optimisation process. Besides, the concept demonstrates the benefits of the compound rotorcraft architecture with a best range speed reaching 90 m/s leading to reduced response times and increase of round trips in a given time. As a consequence, operators will need fewer vehicles and heliports to cover the same areas. This outcome is highly attractive in the current growing market.
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    Novel turboshaft engines design and optimisation for rotorcraft applications.
    (2018-02) Ortiz Carretero, Jesus; Pachidis, Vassilios
    Since the inception of the first gas turbine engines, scientists and aircraft propulsion designers have attempted to improve engine efficiency, size, weight, fuel consumption and power output. In the current scenario, where the conventional gas turbine technology has almost reached its maturity, companies and researchers are starting to seek new engine architectures and novel cycles to comply with the next future aviation challenges. One of the proposed solutions is the implementation of an auxiliary combustion process into the turbines, known as reheated cycle. In the reheated cycle, the gas from an expansion process (through a turbine stage or a whole turbine) is burned before the next expansion. This concept has the potential to increase the specific work, at the same time the thermal efficiency is improved. Numerous investigations have been performed on the application of the reheated cycle to turbojet and civil turbofan engines. However, no studies are published about the potential application of this technology in rotorcraft powerplants. Therefore, the aim of this research project is to accomplish an exhaustive analysis and optimisation of a reheated turboshaft engine in terms of thermal efficiency and engine weight. The optimal engines identified at this stage are to be evaluated at mission level in order to assess the final impact on mission fuel abatement. For this matter, models for the performance simulation of a representative helicopter and for the thermodynamic analysis of the engine architectures have been developed and validated against experimental data. An additional module estimating the cooling flows fluctuation with the engine cycle parameters has been coupled with the engine performance model. Finally, a procedure for the sizing of reheated turboshaft engines have been developed and validated by the author. The different models have been built after a reference Twin-Engine Medium (T EM) helicopter, the Sikorsky UH-60A Black Hawk helicopter powered by two General Electric T700-GE-700 turboshaft engines. The aforementioned models have been integrated in a common simulation framework for the completion of a preliminary parametric analysis showing the sensitivity of the reheated configurations to changes in the engine design variables. In particular, three distinct reheated architectures have been investigated together with a conventional engine for comparison purposes. The individual response of each engine architecture has been discussed. The deployed framework has been then coupled with a Genetic Algorithm optimiser to efficiently seek for the best candidate engines in terms of total weight and Specific Fuel Consumption at cruise (SFCcr). At this step, Response Surface Models (RSMs) have been developed for the fast estimation of engine weight and coupled with the optimiser routine. It has been proven that the reheated engines have the potential to reduce engine mass and increase thermal efficiency in comparison with the baseline engine, although the optimal conventional engine still shows superior performance under the conditions simulated. This conclusion has been also confirmed by the results obtained at mission level. A final mission level multi-objective optimisation has been conducted for the conventional engine targeting the minimisation of the overall mission fuel burn and NOᵪ emissions. A representative model for the prediction of the combustor emissions production has been developed and validated for this purpose. The trade-off existing between fuel efficiency and pollutant depletion has been highlighted along with the potential benefits in block fuel and NOᵪ inventory.