• Journal of Biosystems Engineering
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• v.15 no.4
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• pp.281-289
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• 1990

A frequency-domain, system-identification method using a binary multifrequency signal was developed to find the transfer function between smoke intensity and throttle position in a diesel engine. This paper describes the simulation study performed to test the identification method developed. With an assumption of a diesel operation in a limited region about the normal operating state, the linear theory was adopted. Because that air fuel ratio is one of the most important operating variables causing smoke production in diesel combustion, single-input and single-output model was adopted.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.319-326
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• 2006

In this paper, a fuzzy inference control system is proposed for a turbojet engine with fuel flow control input only. The proposed control system provides a practical fuel flow control method to prevent surge or flame out during engine acceleration or deceleration. A fuzzy logic is designed to obtain the fast acceleration and deceleration of the engine under the condition that the operating point should stay between the surge line and flame out control line. With using both engine rotating speed error and surge margin as fuzzy input variables, the desired engine rotating speed can be achieved to rapidly follow the engine control line without engine stall. Computer simulation using the MATLAB is realized to prove the proposed control performance to the turbojet engine which is linear modelized using DYGABCD program package.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.75-81
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• 2006

Thermal effect of finite-rate chemistry on linear combustion stability and film-cooling effect are investigated in sample rocket engines. The flow variables required to evaluate stability limits are obtained from CFD data with finite-rate chemistry adopted in three dimensional chamber. Major flow variables are affected appreciably by finite--rate chemistry and thereby, the calculated stability limits are modified. It is found that finite-rate chemistry contributes to stability enhancement in thermal point of view. And film cooling also has the effect of combustion stabilization.

• The KSFM Journal of Fluid Machinery
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• v.15 no.4
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• pp.27-32
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• 2012

Gas turbines for an aircraft have the start and restart capabilities within their flight envelop. It is an important item for engine qualification and substantiated with the test. Experimental investigations were carried out to find the relation between the corrected torque and the corrected rotating speed of an air turbine starter in this study. A dedicated air supply system for the air turbine starter and a special device to measure the torque and the rotating speed of the air turbine starter were developed and installed at the altitude engine test facility in Korea Aerospace Research Institute. Experimental results show that the relations between the corrected torque and the corrected rotating speed of the air turbine starter are linear and the inlet temperature and pressure conditions for the air turbine starter were found out to provide minimum required torque for the engine qualification test at various altitude. The start and restart tests for the currently developing engine were successfully performed using this experimental results.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.34-40
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• 2005

In this paper we propose a turbojet engine controller of unmanned aircraft based on the Fuzzy-PI algorithm. To prevent any surge or a flame out event during the engine acceleration or deceleration, the PI-type fuzzy controller effectively controls the fuel flow input of the control system. The fuzzy inference rule made by the logarithm function of acceleration error improves the tracking error. Computer simulations applied to the linear model of a turbojet engine show that the proposed method has good tracking performance for the reference acceleration and deceleration commands.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.104-111
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• 2009

A ship engine operator should compensate the crankshaft assembly of ship engine after inspecting crankshaft deflection error in the crank throw regularly to avoid engine vibration and abrasions. In the previous method, the operator enters the bed plate and measures crankshaft deflection using dial gauge on rotating crankshaft manually. However, this method can cause dangerous situation to the operator as well as uncomfortable in an inferior environment. In order to solve the problems, this paper studies the method which makes the operator measure the error outside of the bed plate. In this paper, it is suggested that BlueTooth wireless communication transfers the error data to the outer standing operator with digitalized crankshaft deflection inspection device developed in this paper. So, the wireless measurement system is developed and applied to a medium-speed marine engine through size-miniaturization. After applying test, the developed inspection device showed that it provides much safe and ease inspection method. Furthermore, in the result, the measuring accuracy is more improved.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.52-60
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• 2020

This paper deals with an optimal output tracking control for open-cycle liquid propellant rocket engine. For this purpose, we modeled simplified mathematical model of open-cycle liquid propellant rocket engine and designed optimal output feedback control system using combustion chamber pressure. For design the closed-loop system of open-cycle liquid propellant rocket engine, we designed optimal output feedback linear quadratic tracking control system using the linearized model and demonstrated the performance of the controller through numerical simulation.

• Advances in aircraft and spacecraft science
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• v.5 no.3
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• pp.349-362
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• 2018

A non-linear numerical simulation technique for predicting the unsteady performances of an airbreathing engine is developed. The study focuses on the simulation of integrated propulsion systems, where a closer coupling is needed between the airframe and the engine dynamics. In fact, the solution of the fully unsteady flow governing equations, rather than a lumped volume gas dynamics discretization, is essential for modeling the coupling between aero-servoelastic modes and engine dynamics in highly integrated propulsion systems. This consideration holds for any propulsion system when a full separation between the fluid dynamic time-scale and engine transient cannot be appreciated, as in the case of flow instabilities (e.g., rotating stall, surge, inlet unstart), or in case of sudden external perturbations (e.g., gas ingestion). Simulations of the coupling between external and internal flow are performed. The flow around the nacelle and inside the engine ducts (i.e., air intakes, nozzles) is solved by CFD computations, whereas the flow evolution through compressor and turbine bladings is simulated by actuator disks. Shaft work balance and rotor dynamics are deduced from the estimated torque on each turbine/compressor blade row.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.93-103
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• 1999

The steady-state performance analysis program for turboprop engine which was used for a small, middle industrial aircraft and a basic trainer aircraft was developed and linear Gas Path Analysis method was applied to Engine Health Monitoring for Turboprop engine. This program was compared with TURBOMARCH program which is well known with performance and power according to flight Mach No. at the standard atmospheric condition to prove a steady-state performance analysis program. From the result, inlet, exit temperature and pressure of each component had error within 3% and especially power according to flight Mach No. had error within 2.4% so that this program could be assured. To make sure if linear Gas Path Analysis is reasonable four cases were selected. The first is the case that fouling is occurred in compressor only. The second is the case that fouling is occurred in compressor and erosion is occurred in turbine. The third is the case that erosion is occurred in both compressor and turbine and power turbine at the same time. Finally, the case that fouling and erosion are occurred in compressor, compressor turbine and power turbine was selected. Different parameters were selected impartially among the independent parameters so that the effect of measurement parameter selection was observed. From the result, the more measurement parameters the smaller RMS error and even though the number of measurement parameters was the same, the RMS error was obtained differently according to which measurement parameters were selected. The case using eight instrument parameters of case IV-4 had small error comparably and was economic and it was important to select optimal number of measurement and optimal measurement parameters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.80-87
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• 2004

To understand the each performance parameter correlation of flight type liquid-propellant rocket engine for KSR-III(Korea Sounding Rocket-III), the analysis of engine stand-alone combustion test results was carried out. Considering the variation of ablative material combustion chamber caused by erosion, linear regression analysis that ignores oxidizer/fuel ratio effect and two-variable 2nd-order polynomial regression analysis that considers oxidizer/fuel ratio change were performed. It can be described that linear regression analysis is simple and very practical method, and can predict the performance within 1% error inside analyzed region. And two-variable 2nd-order polynomial regression analysis can predict with very high accuracy inside region and shows that KSR-III engine's optimum oxidizer/fuel ratio for thrust(or specific impulse) is 2.22 and that for combustion chamber pressure(or characteristic velocity) is 2.17.