Browsing by Author "Pachidis, Vassilios"

Browsing by Author "Pachidis, Vassilios"

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  • Assessment of thermo-electric power plants for rotorcraft application 
    Roumeliotis, Ioannis; Mourouzidis, Christos; Zafferetti, Mirko; Deniz, Unlu; Broca, Olivier; Pachidis, Vassilios (ASME, 2019-10-01)
    This 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 ...
  • Body-force and mean-line models for the generation of axial compressor sub-idle characteristics 
    Righi, Mauro; Ferrer-Vidal, Espana-Heredia Luis; Pachidis, Vassilios (Cambridge University Press, 2020-07-07)
    This paper describes the application of low-order models to the prediction of the steady performance of axial compressors at sub-idle conditions. An Euler body-force method employing sub-idle performance correlations is ...
  • Characterisation of turbine behaviour for an engine overspeed prediction model 
    Pawsey, Lucas; Rajendran, David John; Pachidis, Vassilios (Elsevier, 2017-11-28)
    This paper focuses on the characterisation of turbine overspeed behaviour to be integrated into an engine overspeed model capable of predicting the terminal speed of the high pressure turbine (HPT) in the event of a high ...
  • A characteristic-based 1D axial compressor model for stall and surge simulations 
    Kissoon, Sajal; Righi, Mauro; Pawsey, Lucas; Pachidis, Vassilios; Tunstall, Richard; Roumeliotis, Ioannis (American Society of Mechanical Engineers (ASME), 2023-09-09)
    A low-order unsteady one-dimensional axial compressor and combustor model has been developed at Cranfield University as part of a larger unsteady gas turbine engine model, with the ability to simulate compressor stall and ...
  • Characterization of axial compressor performance at locked rotor and torque-free windmill conditions 
    Ferrer-Vidal, Luis E.; Iglesias-Pérez, Alejandro; Pachidis, Vassilios (Elsevier, 2020-04-28)
    Prediction of aero-engine performance in the sub-idle regime is becoming increasingly important. Performance prediction tools rely on component maps to enable system-level simulations. Methods to obtain compressor sub-idle ...
  • Comparative assessment of fouling scenarios in an axial flow compressor 
    Templalexis, Ioannis; Pachidis, Vassilios; Azamar, Hasani (American Society of Mechanical Engineers, 2020-12-05)
    It is commonly accepted that fouling degrades severely axial compressor performance. Deposits build up as operating hours sum up, causing a decrease in the compressor's delivery pressure, efficiency and flow capacity. ...
  • Comparative assessment of fouling scenarios in an axial flow compressor (Conf) 
    Templalexis, Ioannis; Pachidis, Vassilios; Hasani, Azamar (American Society of Mechanical Engineers, 2021-01-11)
    It is commonly accepted that fouling degrades severely axial compressor performance. Deposits build up throughout the compressor’s operating life, causing a decrease in its delivery pressure, efficiency and flow capacity. ...
  • Considerations on axial compressor bleed for sub-idle performance models 
    Roig Tió, Ferran; Ferrer-Vidal, Luis E.; Azamar Aguirre, Hasani; Pachidis, Vassilios (American Society of Mechanical Engineers, 2021-01-11)
    The trend towards increased bypass ratio and reduced core size in civil aero-engines puts a strain on ground-start and relight capability, prompting renewed interest in sub-idle performance modelling. While a number of ...
  • Control of flow separation in a high-speed compressor cascade through acoustic excitation 
    Coskun, Seyfettin; Rajendran, David John; Pachidis, Vassilios; Bacic, Marko (AIAA, 2023-06-08)
    The use of acoustic excitation for controlling flow separation in a NACA65-K48 linear compressor cascade operating at aircraft engine representative Ma = 0.67 and chord-based Re = 560,000 is investigated numerically. ...
  • Control of flow separation over an aerofoil by external acoustic excitation at a high Reynolds number 
    Coskun, Seyfettin; Rajendran, David John; Pachidis, Vassilios; Bacic, Marko (AIP Publishing, 2024-01-05)
    The effectiveness of acoustic excitation as a means of flow control at high Reynolds number turbulent flows is investigated numerically by using Improved Delayed Detached Eddy Simulations. Previous studies on low Reynolds ...
  • A design approach for controlled blade-off in overspeeding turbines 
    Eryilmaz, Ibrahim; Pachidis, Vassilios (Elsevier, 2022-04-18)
    Following a shaft failure or loss of load in a gas turbine engine, the turbine overspeeds due to the continuing expansion through the stage(s). The overspeed may result in hazardous conditions which have to be prevented. ...
  • Design evaluation and performance assessment of rotorcraft technology by 2050 
    Stevens, Jos; Rademaker, Edward; Scullion, Calum; Vouros, Stavros; van Oosten, Nico; Misté, Gianluigi; Venturelli, Giovanni; Nalianda, Devaiah; Pachidis, Vassilios; Benini, Ernesto (Netherlands Aerospace Centre (NLR), 2019-09-17)
    The extended Clean Sky Joint Technology Initiative (JTI) within the EU Horizon 2020 Framework Programme [Ref. 1] proposes to introduce a number of concept aircraft and rotorcraft to replace reference technology counterparts ...
  • Design exploration and performance assessment of advanced recuperated hybrid-electric UAM rotorcraft 
    Saias, Chana Anna; Roumeliotis, Ioannis; Goulos, Ioannis; Pachidis, Vassilios; Bacic, Marko (American Society of Mechanical Engineers, 2021-11-09)
    The design of efficient, environmentally friendly and quiet powerplant for rotorcraft architectures constitutes a key enabler for Urban Air Mobility application. This work focuses on the development and application of a ...
  • Design methodology and mission assessment of parallel hybrid electric propulsion systems 
    Ghelani, Raj; Roumeliotis, Ioannis; Saias, Chana Anna; Mourouzidis, Christos; Pachidis, Vassilios; Norman, Justin; Bacic, Marko (American Society of Mechanical Engineers, 2022-09-16)
    An 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 ...
  • Design space exploration of turbine blade shroud interlock for flutter stability 
    Larrieta, Olatz; Alonso, Roberto; Pérez Escobar, Óscar; Eryilmaz, Ibrahim; Pachidis, Vassilios (American Society of Mechanical Engineers, 2021-01-11)
    The geared turbofan engines bring the potential to rotate the fan at lower speed and allow an increase in diameter, which in turn leads to an increase in propulsive efficiency through high by-pass ratio. The low-pressure ...
  • Development of a research model to study the operability of a variable pitch fan aero engine in reverse thrust 
    Rajendran, David John; Bentley, David; Azamar Aguirre, Hasani; Tunstall, Richard; Pachidis, Vassilios (Global Power and Propulsion Society, 2020-09-09)
    A rationale for the level of model fidelity required to provide the most representative flow field information to ascertain the feasibility of using a Variable Pitch Fan (VPF) in a modern high bypass ratio aero engine to ...
  • Development of a streamline curvature axial-flow compressor performance simulator graphical-user-interface for design and research 
    Azamar Aguirre, Hasani; Pachidis, Vassilios; Templalexis, Ioannis (International Society for Air Breathing Engines (ISABE), 2017-09-11)
    The all-time interest to increase turbomachinery efficiencies and pressure ratios has led to the progression of more robust and accurate simulation methods and tools. Even though 3-D CFD analyses are highly detailed and ...
  • Ducted Tail Rotor Perfomance Prediction Using CFD 
    Karamolegkos, Konstantinos (Cranfield University, 2014-05-12)
    Aviation industry has a crucial impact on society on the grounds that it offers wider social and economic benefits. The demand of transportation is increasing and it is expected that the worldwide fleet of aircraft and ...
  • A dynamic convergence control scheme for the solution of the radial equilibrium equation in through-flow analyses 
    Pachidis, Vassilios; Templalexis, I.; Pilidis, Pericles; Kotsiopoulos, P. (Professional Engineering Publishing, 2010-01-31)
    One of the most frequently encountered numerical problems in scientific analyses is the solution of non-linear equations. Often the analysis of complex phenomena falls beyond the range of applicability of the numerical ...
  • Dynamic simulation of a rotorcraft hybrid engine in Simcenter Amesim 
    Roumeliotis, Ioannis; Nikolaidis, Theoklis; Pachidis, Vassilios; Broca, Olivier; Unlu, Deniz (European Rotorcraft Forum, 2018-09-30)
    This paper assesses a series hybrid propulsion system utilizing a recuperated gas turbine configuration. An adapted engine model capable to reproduce a turboshaft engine steady state and transient operation is built and ...