• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.79-85
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• 2004

This work treats a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. Investigated are the engine emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to $180^{\circ}C$ in the inlet-air temperature. A controlled auto-ignition gasoline engine can be achieved the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxides had been significantly reduced by CAI combustion compared with conventional spark ignition engines.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.36-47
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• 2000

Three-dimensional compressible turbulent flow fields within the passage of a diffusing S-duct have been simulated by solving the Navier-Stokes equations with SIMPLE scheme. The average inlet Mach number is 0.6 and the Reynolds number based on the inlet diameter is $1.76{\times}10^6$ The extended $k-{\varepsilon}$ turbulence model is applied to modeling the Reynolds stresses. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with experimental wall static-pressure, total-pressure fields, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and streamlines in the symmetric plane are presented. The computed results depict the interaction between the low energy flow by the flow separation and the high energy flow by the reversed duct curvature. The computed results obtained using the extended $k-{\varepsilon}$ turbulence model.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.541-546
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• 1987

An experimental study has been conducted to investigate the suction performance of a designed inlet. Total pressure distortion in the inlet S-duct was measured and the effect of lip thickness and throat area was analyzed. The volume flow rate of air into the turbojet engine was controlled to observe the effect of engine RPM to the total pressure distortion. The pressure data from 36 air tubes were obtained using scanivalve, pressure transducer, and visicoder system.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.48-56
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• 1991

This paper describes the experimental investigations on the pressure variations of intake and exhaust manifold and mass flow rate through exhaust turbine of turbocharged 6-cylinder diesel engine. The turbocharger of experimental diesel engine is constructed with the radial ty pe exhaust turbine and blower driven by exhaust gases. The pressure variations were measur ed by pressure transducer at the points such as turbine inlet and outlet, compressor inlet and outlet, and inlet pipe and exhaust manifolds for normal and combined charging engines with the change of engine speed. The experimental results of this study show that the mass flow rate of exhaust turbine and the variations of pressure in intake and exhaust manifold are all increased with the increase of engine speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.131-139
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• 2001

Highly accurate control of the air-fuel ratio is important to reduce exhaust gas emissions of the gaseous-fuel engines. In order to achieve this purpose, inlet air mass flow must be measured exactly, and precise engine models are necessary to design engine control systems. In this paper, the effects of water vapor and gaseous fuel that change the air mass flow are studied. The effective air mass ratio is defined as the air mass flow divided by the mixture mass flow, and also it is applied to the estimation of the inlet air mass flow. The presence of the gaseous fuel and the water vapor in the mixture reduces the air partial pressure and the effective air mass ratio of the gaseous-fuel engines. The Experimental results for an LPG engine show that the estimation of the inlet ai mass flow based upon the effective air mass ratio is more accurate than that of the normal air mass flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.106-109
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• 2006

The purpose of this study is to analyze the installed performance of the PW206C turbo shaft engine used in the development of the smart UAV(Unmanned Ariel Vehicle) by KARI(Korean Aerospace Research Institute). It mainly aims to investigate performance behavior at installed conditions using both inlet and exhaust losses generated by CFD analysis of the ducts. The ways employed to be able to analyze the performance extensively were mainly rallied out by performing design point analysis of the engine where the performance simulation results from the commercial program 'GASTURB 9' used for simulation were used as inlet boundary condition for the ducts in CFD program The use of CFD tool involve modeling of the ducts to conform with the stipulated shape and sizes as defined by KARI with a grid density that allows reasonable flow characteristics applicable to aircraft components. Respective values of Shaft horse power obtained by varying flight Mach number, Gas generator RPM and Altitude considering several losses inclusive of those estimated by use of CFD tool were then plotted at three conditions with the ECS-OFF, ECS-MAX and at un-installed condition. Reasonable results were obtained as a result of using computational fluid dynamics that can hence be justified as an alternative tool for use in future flow analysis of engine and components.

• Advances in aircraft and spacecraft science
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• v.5 no.4
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• pp.431-444
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• 2018

Numerical simulations have been conducted to study the unstart/restart characteristics of an over-under turbine-based combined-cycle propulsion system (TBCC) inlet during the inlet transition phase. A dual-solution area exists according to the Kantrowitz theory, in which the inlet states may be different even with the same input parameters. The entire transition process was divided into five stages and the unstart/restart hysteresis loop for each stage was also obtained. These loops construct a hysteresis surface which separates the operating space of the engine into three parts: in which a) inlet can maintain a started state; b) inlet keeps an unstarted state; c) inlet state depends on its initial state. During the transition, the operation of the engine follows a certain order with different backpressures and splitter angles, namely control route, which may result in disparate inlet states. Nine control routes with different backpressures and transition stages were designed to illuminate the route-dependent behavior of the inlet. The control routes operating towards the unstart boundary can make the inlet transit from a started state into an unstarted one. But operating backward the same route cannot make the inlet restart, additional effort should be made.

• Journal of ILASS-Korea
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• v.14 no.1
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• pp.34-38
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• 2009

This paper presents the pulsation of carburetor inlet and outlet pressure of a small SI gasoline engine. The engine used in this paper is a 23cc, single cylinder, diaphragm carburetor, two-stroke, air-cooled for brush cutter. The rpm and pressure wave pulsation at the inlet and the outlet of carburetor were measured and analysed for the understand of the internal air flow into the barrel on the diaphragm carburetor. These data should be used for the development of the duel fuel injection system for gasoline and LPG. The results showed that the carburetor inlet pressure variations were very steady, but the pressure variations at carburetor outlet were very sensitive to the pressure variation into the crank case and were to similar independently to the engine speed on partial opened throttle conditions. According to increasing engine speed, the pressure waves started to come out and be developed after closing the intake port of the engine at carburetor outlet. Reverse flow occurred on the WOT (wide open throttle) condition.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.23-32
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• 2012

The present study is aimed to develop an integrated performance analysis approach for the application of a compressor with variable inlet guide vane (VIGV) and vairable stator vane (VSV) in a small turbofan engine. For the integrated analysis approach, an engine performance analysis program, NPSS and a computer program used for predicting of axial flow compressor performance based on stage stacking method, STGSTK were linked with an optimisation package, Isight. This enables off-design performance analysis for the turbofan engine with VIGV and VSV hence provides the capability to predict stable operation condition of the engine with acceptable surge margin.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.29-34
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• 2007

The purpose of this paper was to address the methodology of the air flow measurement using duct mach number that was considered area-weighed average obtained by total pressure and temperature measured at engine inlet duct. Without installing boundary rake, the prediction of air flow measurement was discussed. Actual air flow measurement and pressure value using pressure loss through inlet seal were described to improve the reliability and operability of altitude engine test facility.