Small-scale Gas Turbine Engine Research Articles

Fully Coupled Turbojet Engine Computational Fluid Dynamics Simulations and Cycle Analyses Along the Equilibrium Running Line

Abstract This work presents fully coupled computational fluid dynamics (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.

Digital twin of rig for testing of centrifugal compressor for small-scale gas turbine engine

Digital twin of rig for testing of centrifugal compressor for small-scale gas turbine engine

Reduction of fuel consumption of a small-scale gas turbine engine with fine bubble fuel

Thermal efficiency of the small-scale gas turbines (SSGTs) is much less than that of large-scale gas turbine. Therefore, improvement of thermal efficiency of SSGTs is very important. In this paper, fine bubble fuel (FBF) which is fuel mixed with air fine bubbles (AFBs) was introduced to SSGT to improve its thermal efficiency. Control fuel (CF) and FBF were tested on a SSGT. Specific fuel consumption (SFC) of the engine can be reduced about 2.6%–5.7% at a maximum and about 1.7%–2.7% as an average by using FBF compared to CF. To validate the effect AFBs on the reduction of fuel consumption (FC), droplet size distribution of CF and FBF injected by a nozzle was measured. It was found that atomization of droplets can be promoted by introducing AFBs to fuel, and D32 can be reduced about 4.4%. However, from the results of a simulation of combustion in the combustion chamber, considerable effect of atomization was not observed. Therefore, the effect of atomization of fuel on the reduction of FC is relatively small, and there are other reasons, such as promotion of diffusive combustion due to air which exists in fuel as AFBs.

Термодинамическое проектирование семейства малоразмерных газотурбинных двигателей

The paper presents a procedure for selecting work cycle parameters and describes thermodynamic design of a small-scale gas turbine engine family consisting of a small-scale gas turbine engine and a gas turbine plant comprising a free turbine driving a power generator, on the basis of a standardized gas generator. In order to select reasonable work cycle parameter values for the small-scale gas turbine engine and gas turbine plant we used a non-linear optimisation technique accounting for functional and parametric constraints as implemented in the ASTRA CAE software. Calculation results allowed us to plot the locally optimal work cycle parameter regions for the small-scale gas turbine engine and gas turbine plant according to the efficiency criteria for both engines, which are specific fuel consumption and net energy conversion efficiency. Taking the constraints into account, we selected reasonable values for the standardized gas generator parameters within the compromise region obtained, specifically the turbine inlet temperature and compressor pressure ratio. Our quantitative results show how the efficiency indices decline in the engine family featuring a standardized gas generator as compared to engines equipped with individually tailored gas generators. Designing a standardized gas generator in advance makes it possible to decrease engine development costs and time, ensure a higher reliability and a lower cost of production.

Development of various types of small-scale gas turbine engines based on a unified core engine

Development of various types of small-scale gas turbine engines based on a unified core engine

Автоматизированное проектирование и расчет неохлаждаемой осевой ступени турбины малоразмерного газотурбинного двигателя

Автоматизированное проектирование и расчет неохлаждаемой осевой ступени турбины малоразмерного газотурбинного двигателя

Thermodynamic designing of the small-scale gas turbine engine family with common core

The paper describes the method of selecting the working process parameters of a family of small-scale gas turbine engines (GTE) with common core. As an example, the thermodynamic design of a family of small-scale gas turbine engines (SGTE) with common core was carried out. The engine family includes a small-scale turbojet engine (STJE) and a gas turbine plant (GTP), which electric generator is driven by power turbine. The selection of rational values for the working process parameters of STJE and GTP was carried out in CAE system ASTRA on the basis of nonlinear optimization of these parameters, taking into account functional and parametric constraints. The quantitative results of deterioration in the performance of the engines of the family with common core are obtained in comparison with the engines with the optimum core for each type. However, the advanced creation of a common core can reduce the cost and timing of the engine creation, ensure its higher reliability (due to the development of the base common core) and reduce the cost of its production. The method of selecting the parameters of the working process of the GTE family with common core presents the solution to more complex problems, such as the possibility of developing a family consisting of five engines: a turbojet engine, turbofan engine, turbofan engine with a complex cycle, GTE with power turbine (GTE-PT), GTE-PT with recovery.

Performance and emission characteristics of biofuel in a small-scale gas turbine engine

Performance and emissions characteristics of a 30 kW gas turbine engine burning Jet A, soy methyl ester, canola methyl ester, recycled rapeseed methyl ester, hog-fat biofuel, and their 50% (volume) blends in Jet A were studied over a range of throttle settings. The addition of biofuel resulted in a reduction in static thrust and thrust-specific fuel consumption, and increased thermal efficiency. The CO and NO emissions from the turbine were reduced with the biofuel blends. The results suggest that an optimum mixture may be found that reduces pollutant emissions while producing the desired thrust. This study demonstrates that biofuels may serve as viable supplements to petroleum-based fuels.

Design and control of a brushless DC limited-angle torque motor with its application to fuel control of small-scale gas turbine engines

This paper presents techniques for design and control of a brushless direct-current (DC) limited-angle torque motor (LATM) with its application to fuel control of gas turbine engines. Given the desired specifications, a two-pole brushless DC LATM with a toroidally wound armature is designed using selected ferromagnetic material and rare-earth permanent magnets; its electromagnetic characteristics is then computationally found and well tuned using the finite element method (FEM) in order to ensure whether the design meets the performance specifications. To achieve the simple and inexpensive semi-closed-loop fuel control, a robust position controller (including a proportional-integral-derivative (PID) controller with a prefilter) is synthesized for providing the required positioning performance for the developed motor, thereby achieving an inexpensive semi-closed-loop fuel control. A closed-loop fuel controller associated with the proposed position controller and a flow meter is then proposed based on multi-loop control structure in order to achieve required linear input–output relationship. All the proposed fuel control laws were implemented using a stand-alone single-chip digital signal processor (DSP). Experimental results are conducted to show the efficacy and usefulness of the developed limited-angle torque motor with its application to an experimental gas turbine fuel control test platform.

Development of techniques to characterize particulates emitted from gas turbineexhausts

Particles emitted from aircraft play a role in the formation of contrails and it isessential to characterize them to understand the physical and chemical processesthat are happening. Current methods for measuring aircraft particulateemissions study the reflectance of samples collected in filter papers.Aseries of experiments to more fully characterize particulates has beenperformed on a small-scale gas turbine engine. An intrusive samplingsystem conforming to current ICAO regulations for aircraft emissionswas used with a scanning mobility particle sizer (SMPS). Non-intrusivemeasurements were made using laser induced incandescence (LII) andsamples were taken from the exhaust to analyse using a transmissionelectron microscope. Results obtained from different techniques showed goodagreement with each other. As engine power conditions increased, both theSMPS and LII indicated that the mass of soot had decreased. Differenceswere observed between measurements of diluted and undiluted samples.The mean particle size decreased with dilution but the size distributionbecame bi-modal.The study has shown how significant the samplingenvironment is for measuring particulates and careful techniques needto be used to ensure that accurate, consistent results can be obtained.