Influence of Impeller Geometry on Efficiency of the Centrifugal Compressor of a Small-Scale Turbojet Engine

Having a small-scale turbojet engine operate at a desired speed with minimum steady state error, while maintaining good transient response is crucial in many applications, such as UAVs, and requires precise control of the fuel flow. In this paper, first the mathematical model of a Small-Scale Turbojet Engine (SSTE) is obtained using system identification tests, and then based on this model, a classical PI controller is designed. Afterwards, to improve on the transient response and steady state performance of this classical controller, a Fuzzy Logic Controller (FLC) is designed. The design process for the FLC employs logical deduction based on knowledge of the engine behavior and iterative tuning in the light of software- and hardware-in-the-loop simulations. The classical and fuzzy logic controllers are both implemented on an in-house, embedded Electronic Control Unit (ECU) running in real time. This ECU is an integrated device carrying a microcontroller based board, a fuel pump, fuel line valves, speed sensor and exhaust gas temperature sensor inputs, and starter motor and glow plug driver outputs. It mainly functions by receiving a speed reference value via its serial communication interface. Based on this reference, a voltage is calculated and applied to the fuel pump in order to regulate the fuel flow into the engine, thereby bringing the engine speed to the desired value. Pre-defined procedures for starting and stopping the engine are also automatically performed by the ECU. Further, it connects to a computer running an in-house comprehensive Graphical User Interface (GUI) software for operating, monitoring, configuration and diagnostics purposes. The designed controllers are used to drive a generic SSTE. Reference inputs consisting of step, ramp and chirp profiles are applied to the controllers. The engine response using both controllers are recorded and inspected. The results show that the FLC exhibits a comparable performance to the classical controller, with possible opportunities to improve this performance.

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Performance of a small-scale turbojet engine fed with traditional and alternative fuels

Energy Conversion and Management ◽

10.1016/j.enconman.2014.03.026 ◽

2014 ◽

Vol 82 ◽

pp. 219-228 ◽

Cited By ~ 29

Author(s):

M. Badami ◽

P. Nuccio ◽

D. Pastrone ◽

A. Signoretto

Keyword(s):

Alternative Fuels ◽

Small Scale ◽

Turbojet Engine

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Mathematical Modelling for Carbon Dioxide Equivalent Prediction of Greenhouse Gases Emitted from a Small Scale Turbojet Engine

7th AIAA Atmospheric and Space Environments Conference ◽

10.2514/6.2015-3326 ◽

2015 ◽

Cited By ~ 2

Author(s):

Yasin Şöhret ◽

Tahir H. Karakoc ◽

Nimet Karakoç

Keyword(s):

Carbon Dioxide ◽

Mathematical Modelling ◽

Greenhouse Gases ◽

Small Scale ◽

Turbojet Engine ◽

Carbon Dioxide Equivalent

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Fully-Coupled Turbojet Engine CFD Simulations and Cycle Analyses Along the Equilibrium Running Line

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4049410 ◽

2020 ◽

Author(s):

Alejandro Briones ◽

Andrew W Caswell ◽

Brent Rankin

Keyword(s):

Flow Rate ◽

Fluid Dynamic ◽

Thermodynamic Cycle ◽

Angular Speed ◽

Small Scale ◽

Cfd Simulations ◽

Fuel Flow ◽

Turbojet Engine ◽

Design Cycle ◽

Fully Coupled

Abstract This work presents fully-coupled computational fluid dynamic (CFD) simulations and thermodynamic cycle analyses of a small-scale turbojet engine at several conditions along the equilibrium running line. The CFD simulations use a single mesh for the entire engine, from the intake to the exhaust, allowing information to travel in all directions. The CFD simulations are performed along the equilibrium running line by using the iterative Secant method to compute the fuel flow rate required to match the compressor and turbine power. The freestream pressure and temperature and shaft angular speed are the only inputs needed for the CFD simulations. To evaluate the consistency of the CFD results with thermodynamic cycle results, outputs from the CFD simulations are prescribed as inputs to the cycle model. This approach enables on-design and off-design cycle calculations to be performed without requiring turbomachinery performance maps. In contrast, traditional off-design cycle analyses require either scaling, calculating, or measuring compressor and turbine maps with boundary condition assumptions. In addition, the CFD simulations and the cycle analyses are compared with measurements of the turbojet engine. The CFD simulations, thermodynamic cycle analyses, and measurements agree in terms of total temperature and pressure at the diffuser-combustor interface, air and fuel mass flow rate, equivalence ratio, and thrust. The developed methods to perform CFD simulations from the intake to the exhaust of the turbojet engine are expected to be useful for guiding the design and development of future small-scale gas turbine engines.

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Centrifugal Compressor of a 100 kW Microturbine: Part 1 — Experimental and Numerical Investigations on Overall Performance

Volume 3: Turbo Expo 2003 ◽

10.1115/gt2003-38152 ◽

2003 ◽

Cited By ~ 1

Author(s):

E. Benini ◽

A. Toffolo ◽

A. Lazzaretto

Keyword(s):

Numerical Model ◽

Centrifugal Compressor ◽

Small Scale ◽

Turbine Engine ◽

Sliding Mesh ◽

Extensive Test ◽

Rotor Stator Interaction ◽

Compressor Performance ◽

True Time ◽

Operating Points

This paper describes on/off design performance of a centrifugal compressor of a 100 kW turbogenerator gas turbine engine used for small scale power generation. The compressor stage is made up of a radial impeller and a two-stage diffuser (radial and deswirl). Part 1 deals with the experimental and numerical tests on overall compressor and diffuser performance: An extensive test series with steady probe measurements at impeller exit and diffuser exit is performed at different operating points and rotational speeds. This makes it possible to characterize both overall compressor and diffuser. The numerical model is based on a mixing plane at impeller-diffuser interface and therefore neglects the effect of unsteadiness due to rotor-stator interaction. Then, in part 2 the true time-dependent interaction is investigated by means of a numerical model where a sliding mesh technique is adopted. The unsteady results are then processed and compared with the steady ones regarding the flow in the diffuser. Finally, in part 3 the geometry of the compressor diffuser is optimized using an evolutionary algorithm coupled with a CFD code in order to improve compressor performance.

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Sustainability Metrics of a Small Scale Turbojet Engine

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2016-0036 ◽

2018 ◽

Vol 35 (2) ◽

pp. 113-119 ◽

Cited By ~ 6

Author(s):

Selcuk Ekici ◽

Yasin Sohret ◽

Kahraman Coban ◽

Onder Altuntas ◽

T. Hikmet Karakoc

Keyword(s):

Exergy Efficiency ◽

Sustainability Indicators ◽

Aviation Industry ◽

Small Scale ◽

Exergy Destruction ◽

The Sustainable Development ◽

Effect Factor ◽

Sustainability Index ◽

Turbojet Engine ◽

Power Load

Abstract Over the last decade, sustainable energy consumption has attracted the attention of scientists and researchers. The current paper presents sustainability indicators of a small scale turbojet engine, operated on micro-aerial vehicles, for discussion of the sustainable development of the aviation industry from a different perspective. Experimental data was obtained from an engine at full power load and utilized to conduct an exergy-based sustainability analysis. Exergy efficiency, waste exergy ratio, recoverable exergy ratio, environmental effect factor, exergy destruction factor and exergetic sustainability index are evaluated as exergetic sustainability indicators of the turbojet engine under investigation in the current study. The exergy efficiency of the small scale turbojet engine is calculated as 27.25 % whereas the waste exergy ratio, the exergy destruction factor and the sustainability index of the engine are found to be 0.9756, 0.5466 and 0.2793, respectively.

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Identification of small scale turbojet engine with variable exhaust nozzle

2017 IEEE 15th International Symposium on Applied Machine Intelligence and Informatics (SAMI) ◽

10.1109/sami.2017.7880278 ◽

2017 ◽

Cited By ~ 1

Author(s):

Karoly Beneda ◽

Ladislav Fozo

Keyword(s):

Small Scale ◽

Turbojet Engine

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The Slip Factor of a Radial Bladed Centrifugal Compressor

Journal of Engineering for Power ◽

10.1115/1.3678159 ◽

1965 ◽

Vol 87 (2) ◽

pp. 181-188 ◽

Cited By ~ 4

Author(s):

Alfred F. Stahler

Keyword(s):

Flow Rate ◽

Centrifugal Compressor ◽

Rotational Speed ◽

Gas Flow ◽

Centrifugal Impeller ◽

Gas Flow Rate ◽

Slip Factor ◽

Impeller Geometry

Several of the methods of explaining and evaluating the slip factor of a centrifugal impeller with straight radial blades are presented. The slip factors are calculated by these methods and compared to the experimentally observed characteristics of an impeller with 19 blades. It is shown that the slip factor depends on the gas-flow rate, the rotational speed, and the impeller-tip diameter. It is concluded that the slip-factor characteristics are better described by means of a constant leaving angle of the flow relative to the impeller and that the leaving angle is only a function of the impeller geometry.

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