The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

K. Mathioudakis - One of the best experts on this subject based on the ideXlab platform.

  • Contra-Rotating Propeller Modelling for Open Rotor Engine Performance Simulations
    Volume 1: Aircraft Engine; Fans and Blowers; Marine, 2016
    Co-Authors: A. Alexiou, C. Frantzis, N. Aretakis, Vassilios Riziotis, I. Roumeliotis, K. Mathioudakis
    Abstract:

    This paper presents a method for modelling contra-rotating propellers (CRP) for Engine Performance simulations. An in-house free-wake lifting surface tool (GENUVP) is used to generate suitable Performance maps for each propeller that express power and thrust coefficient in terms of advance ratio, flight Mach number, speed ratio and blade pitch angle of each propeller. Appropriate component models that utilize these maps are then developed in a commercial Engine Performance simulation environment (PROOSIS). Next, the propeller components are integrated in a direct-drive open rotor Engine model. Finally, design point and off-design simulations are carried out that demonstrate the use of the model through studies of different propeller blade angle control strategies.

  • Gas Turbine Engine Performance Model Applications Using an Object-Oriented Simulation Tool
    Volume 2: Aircraft Engine; Ceramics; Coal Biomass and Alternative Fuels; Controls Diagnostics and Instrumentation; Environmental and Regulatory Affair, 2006
    Co-Authors: A. Alexiou, K. Mathioudakis
    Abstract:

    Engine Performance models are used throughout the life cycle of an Engine from conceptual design to testing, certification and maintenance. The objective of this paper is to demonstrate the use and advantages of an Engine Performance model, developed using an object-oriented simulation tool, for the following applications: • Building an Engine model from existing Engine components and running steady state and transient calculations. • Development and integration of a new cooled turbine component in the existing Engine model. • Accessing the Engine model from an external application. • Using an external legacy routine in the Engine model.Copyright © 2006 by ASME

  • Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance
    Volume 5: Turbo Expo 2005, 2005
    Co-Authors: I. Roumeliotis, K. Mathioudakis
    Abstract:

    The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an Engine Performance model is used. The wet compression model produces the compressor Performance map when water is present and consists of a one dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall Performance and individual stage operation is examined. The map generation procedure is embedded in an Engine Performance model and a study of water injection effect on overall Engine Performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor towards stall and that the Performance enhancement is greater as the injection point moves towards compressor inlet.Copyright © 2005 by ASME

  • Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance
    Journal of Engineering for Gas Turbines and Power, 2004
    Co-Authors: I. Roumeliotis, K. Mathioudakis
    Abstract:

    The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an Engine Performance model is used. The wet compression model produces the compressor Performance map when water is present and consists of a one-dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall Performance and individual stage operation is examined. The map-generation procedure is embedded in an Engine Performance model and a study of water injection effect on overall Engine Performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor toward stall and that the Performance enhancement is greater as the injection point moves towards compressor inlet.

Judit Bar-ilan - One of the best experts on this subject based on the ideXlab platform.

  • Methods for measuring search Engine Performance over time
    Journal of the American Society for Information Science and Technology, 2002
    Co-Authors: Judit Bar-ilan
    Abstract:

    This study introduces methods for evaluating search Engine Performance over a time period. Several measures are defined, which as a whole describe search Engine functionality over time. The necessary setup for such studies is described, and the use of these measures is illustrated through a specific example. The set of measures introduced here may serve as a guideline for the search Engines for testing and improving their functionality. We recommend setting up a standard suite of measures for evaluating search Engine Performance.

Zane D. Gastineau - One of the best experts on this subject based on the ideXlab platform.

  • Turbine Engine Performance Improvements—A Proactive Approach
    Journal of Turbomachinery, 2002
    Co-Authors: Zane D. Gastineau
    Abstract:

    Turbine Engine concepts for the future are placing ever increasing demands on the design Engineer. These future systems are seeking to increase Performance while at the same time reduce costs, However traditional Engine design methods use large margins in the design process of a specific component in order to guarantee proper operation throughout the flight envelope over the life of the Engine. These margins in fact reduce Engine Performance and increase the costs, in this paper, active control will be presented as one potential means of achieving the requirements for future turbine Engines. In addition, specific active control applications will be discussed.

  • Turbine Engine Performance Improvements: A Proactive Approach
    Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls Diagnostics and Instrumentation; Education; IGTI Scholar, 2001
    Co-Authors: Zane D. Gastineau
    Abstract:

    Turbine Engine concepts for the future are placing ever-increasing demands on the design Engineer. These future systems are seeking to increase Performance while at the same time reduce costs. However, traditional Engine design methods use large margins in the design process of a specific component in order to guarantee proper operation throughout the flight envelope over the life of the Engine. These margins in fact reduce Engine Performance and increase the costs. In this paper, active control will be presented as one potential means of achieving the requirements for future turbine Engines. In addition, specific active control applications will be discussed.Copyright © 2001 by ASME

I. Roumeliotis - One of the best experts on this subject based on the ideXlab platform.

  • Contra-Rotating Propeller Modelling for Open Rotor Engine Performance Simulations
    Volume 1: Aircraft Engine; Fans and Blowers; Marine, 2016
    Co-Authors: A. Alexiou, C. Frantzis, N. Aretakis, Vassilios Riziotis, I. Roumeliotis, K. Mathioudakis
    Abstract:

    This paper presents a method for modelling contra-rotating propellers (CRP) for Engine Performance simulations. An in-house free-wake lifting surface tool (GENUVP) is used to generate suitable Performance maps for each propeller that express power and thrust coefficient in terms of advance ratio, flight Mach number, speed ratio and blade pitch angle of each propeller. Appropriate component models that utilize these maps are then developed in a commercial Engine Performance simulation environment (PROOSIS). Next, the propeller components are integrated in a direct-drive open rotor Engine model. Finally, design point and off-design simulations are carried out that demonstrate the use of the model through studies of different propeller blade angle control strategies.

  • Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance
    Volume 5: Turbo Expo 2005, 2005
    Co-Authors: I. Roumeliotis, K. Mathioudakis
    Abstract:

    The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an Engine Performance model is used. The wet compression model produces the compressor Performance map when water is present and consists of a one dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall Performance and individual stage operation is examined. The map generation procedure is embedded in an Engine Performance model and a study of water injection effect on overall Engine Performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor towards stall and that the Performance enhancement is greater as the injection point moves towards compressor inlet.Copyright © 2005 by ASME

  • Evaluation of Interstage Water Injection Effect on Compressor and Engine Performance
    Journal of Engineering for Gas Turbines and Power, 2004
    Co-Authors: I. Roumeliotis, K. Mathioudakis
    Abstract:

    The present paper examines the effect of water injection at the compressor inlet or between stages, on its operation. A wet compression model coupled with an Engine Performance model is used. The wet compression model produces the compressor Performance map when water is present and consists of a one-dimensional stage stacking model, coupled with a droplet evaporation model. The effect of water injection on overall Performance and individual stage operation is examined. The map-generation procedure is embedded in an Engine Performance model and a study of water injection effect on overall Engine Performance is undertaken. The possibility to evaluate the effect on various parameters such as power, thermal efficiency, surge margin, as well as the progression of droplets through the stages is demonstrated. The results indicate that water injection causes significant stage rematching, leading the compressor toward stall and that the Performance enhancement is greater as the injection point moves towards compressor inlet.

Richard J. Brown - One of the best experts on this subject based on the ideXlab platform.

  • Engine Performance during Transient and Steady-State Operation with Oxygenated Fuels
    Energy & Fuels, 2017
    Co-Authors: Ali Zare, Timothy A. Bodisco, Nurun Nabi, Farhad M. Hossain, Zoran Ristovski, Richard J. Brown
    Abstract:

    Owing to the increasing share of biofuels in combustion Engines, use of these oxygenated fuels instead of diesel should be evaluated under different Engine operating conditions. This paper studies the influence of oxygenated fuels on Engine Performance parameters under transient, compared to steady-state, operation on a six-cylinder, turbocharged, compression-ignition Engine with a common rail injection system. The fuels used in this study were diesel, waste cooking biodiesel, and triacetin (as a highly oxygenated additive). A custom test was used to investigate different Engine Performance parameters during acceleration, load increase, and steady-state modes of operation. Additionally, a legislative transient cycle (NRTC), composed of many discrete transient modes, was used to study Engine Performance during a whole transient cycle. In this paper, different Engine Performance-related parameters were investigated, such as IMEP, BMEP, FMEP, turbocharger lag, air-to-fuel ratio, Engine speed and torque, star...

  • Microalgae biodiesel: Current status and future needs for Engine Performance and emissions
    Renewable and Sustainable Energy Reviews, 2017
    Co-Authors: Muhammad Aminul Islam, Kirsten Heimann, Richard J. Brown
    Abstract:

    Microalgae feedstock is recognised as one of the most promising resources for producing triglycerides which is subsequently converted to biodiesel. However, the large-scale technology required to generate biodiesel from microalgae is still in its early stages of development. Microalgae research to date may be placed into four broad categories: (i) growth, (ii) harvesting, (iii) oil extraction and (iv) fuel properties for Engine Performance and emissions. More than 1000 manuscripts have been published on the first category with progressively less on subsequent groups. Finally, effects of microalgae methyl esters on Engine Performance have only been reported in 9 scientific articles. This review will place extraction techniques and Engine Performance of microalgae biodiesel in the context of the preceding two categories and examine the practical problems associated with fuel properties, Engine Performance and emissions. Considering energy consumption, toxicity, and time, many of the extraction techniques used in the laboratory show moderate potential for commercial scale. An important finding is that variation of conditions in the first three categories can have a significant effect on biofuel quality which can cause fuel properties to be out of standard and/or adversely affect Engine Performance and emissions.