• Smart Structures and Systems
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• v.7 no.1
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• pp.1-13
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• 2011

It has been shown in the literature that active adjustment of the intake area of a jet engine has potential to improve its fuel efficiency. This paper presents the design and control of a novel proof-of-concept active jet engine intake using Nickel-Titanium (Ni-Ti or Nitinol) shape memory alloy (SMA) wire actuators. The Nitinol SMA material is used in this research due to its advantages of high power-to-weight ratio and electrical resistive actuation. The Nitinol SMA material can be fabricated into a variety of shapes, such as strips, foils, rods and wires. In this paper, SMA wires are used due to its ability to generate a large strain: up to 6% for repeated operations. The proposed proof-of-concept engine intake employs overlapping leaves in a concentric configuration. Each leaf is mounted on a supporting bar than can rotate. The supporting bars are actuated by an SMA wire actuator in a ring configuration. Electrical resistive heating is used to actuate the SMA wire actuator and rotate the supporting bars. To enable feedback control, a laser range sensor is used to detect the movement of a leaf and therefore the radius of the intake area. Due to the hysteresis, an inherent nonlinear phenomenon associated with SMAs, a nonlinear robust controller is used to control the SMA actuators. The control design uses the sliding-mode approach and can compensate the nonlinearities associated with the SMA actuator. A proof-of-concept model is fabricated and its feedback control experiments show that the intake area can be precisely controlled using the SMA wire actuator and has the ability to reduce the area up to 25%. The experiments demonstrate the feasibility of engine intake area control using an SMA wire actuator under the proposed design.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.579-584
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• 2005

Unsteady state free natural gas jets injected from several types of injectors were numerically simulated. Simulations showed good agreements with the schlieren experimental results. Moreover, injections of natural gas in intake manifolds of a single-valve engine and a double-valve engine were predicted as well. Predictions revealed that large volumetric injections of natural gas in intake manifolds led to strong impingement of natural gas with the intake valves, which as a result, gave rise to pronounced backward reflection of natural gas towards the inlets of intake manifolds, together with significant increase in pressure in intake manifold. Based on our simulations, we speculated that for engines with short intake manifolds, reflections of the mixture of natural gas and air were likely to approach the inlets of intake manifolds and subsequently be inbreathed into other cylinders, resulting in non-uniform mixture distributions between the cylinders. For engines with long intake manifolds, inasmuch as the degrees of intake interferences between the cylinders were not identical in light of the ignition sequences, non-uniform intake charge distributions between the cylinders would occur.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.10-20
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• 2022

The performance analysis test of the scramjet engine intake was conducted under the Mach 5 condition of the scramjet engine test facility, a free-jet ground test facility of the Korea Aerospace Research Institute. A pitot/static pressure rake installed at the rear of the isolator was designed and manufactured to measure the total pressure recovery rate and mass capture ratio, which are typical performance factors of the scramjet engine intake. The effect of the rake mounted at the rear of the isolator on the intake, the performance analysis measured by the rake, and the change in wall static pressure distribution according to the angle of attack were performed. Finally, the point at which the intake unstart occurred was confirmed by using the rear back pressure adjusting device, which simulates pressure rise in the combustor, and the results are summarized in this paper.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.42-47
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• 2016

This paper presents the development of a floating outboard type of compact water jet propulsion system. The planning case of the water jet system is developed by performing precision processing after manufacturing FRP (Fiber Reinforced Plastics) from plug mold casting. This system is composed of an intake, impeller, diffuser, reverse bucket, and main shaft. In addition, a rebuilt engine was applied through marine engineering. The water jet propulsion system performance was verified to discharge a maximum $0.29m^3/s$ of flow rate and 37 m/s of flow velocity in a test pool on land. A field test was performed by installing the water jet propulsion device on board a ship that was tested off the coast of Korea. The weight of the hull, engine, and other equipment was approximately 1.2 tons, and the sailing speed was a maximum 22 knots at 3,600 rpm.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.77-87
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• 2022

In order to perform the scramejt engine intake ground test using the Scramjet Engine Test Facility(SETF) of the Korea Aerospace Research Institute. we introduced the test availability check procedure that is generally conducted. The design process of the newly manufactured Mach 5 nozzle for the scramjet intake test was summarized, a device for checking the core flow distribution of the nozzle was explained, and the core flow test analysis results were written. Through a series of test results, it was confirmed that the intake was located in the new Mach 5 nozzle core.

• Journal of Mechanical Science and Technology
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• v.15 no.2
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• pp.259-267
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• 2001

The flow field in a cylinder of a 4-valve pentroof engine is studied using the KIVA-3V code. Turbulence is generated from the jet flow through valves and broken down to the small scale eddies in the compression process. It is known that the tumble effectively keeps turbulence during the compression process. In the combustion process, turbulence is known to enhance flame speed by increasing mass, momentum and heat transfer rates. The effects of the intake port angles on the flow and combustion characteristics are studied in this study. To study the effect of turbulence on the combustion process, Cantore combustion model is applied in this study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.491-498
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• 2004

Lift Fan Engines of JAXA's conceptual Jet VTOL aircraft have a very small bellmouse shape air intake, which make some differences in aerodynamic design of the blades. To obtain a better rotor or stator blade design, this paper performs a numerical analysis of the throughflow on a lift fan as a two-dimensional axisymmetrical flow. Based on the last report focusing on the air intake's influence on the throughflow, a more realistic bellmouse air intake case is treated to reconsider the influence on the throughflow by the small bellmouse air intake. Three work input patterns are tested to reduce some problematic influences on the throughflow or blade designs. The obtained result shows one of acceptable blade designs for the lift fan engine.

• Journal of ILASS-Korea
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• v.12 no.1
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• pp.45-57
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• 2007

This paper presents both experimental and numerical studies regarding nozzles used for the SI engine application, particularly for the intake-port fuel injection type. The atomization mechanism of the multi-hole plate nozzle was investigated experimentally. It was found that the nozzle design added turbulence into the liquid-film jet and the jet disintegrated rapidly. Based on the results, various plate types for the nozzle were developed and tested; six hole nozzle for liquid jet interaction, plate-type nozzle with flat duct channel, and the simpler structured nozzle. The spray characteristics of the prototype nozzles were examined experimentally while the internal flow of the nozzle was investigated computationally. It was shown that turbulent liquid-film was injected and atomization quality was improved by controlling the internal flow condition of the plate-type nozzle.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.15-26
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• 1997

The present study is mainly motivated to numerically simulate the autoignition and combustion process of a diesel spray in RCM and effects of design parameters on combustion and engine performance in the DI diesel engine using EGR. In case of the burning spray in RCM, special emphasis is given to the autoignition process coupled with the fluid mechanics and chemical reaction. Computations are carried out for a wide range of operating condition in terms of temperature, concentration of oxygen and carbon dioxide of the intake gas in the DI diesel engine. Numerical results indicate that the mixing process along the edges of spray jet has a crucial role for autoignition and combustion process. Temperature and concentration of O2 and CO2 of intake gas significantly influence the combustion characteristics and engine performance in the diesel/EGR environment.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.246-252
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• 2014

This study is on the development of 150PS inboard type of compact water jet propulsion system. The water jet is composed of intake, impeller, diffuser, reverse bucket and main shaft. Components of water jet have been manufactured through precision processing after sand casting. Development of water jet propelled engine has been finally completed by processes which are design, production and inspection on each component. The water jet performance characteristics show that 0.29 m3/s of maximum flow rate and 37 m/s of flow velocity have been secured in the ground test pool. Field test was performed by 21ft test ship that water jet propulsion equipment developed in this study was installed. As a result, the weight of hull, engine and other parts of the ship has been almost 1.2 ton and 45 km/h of maximum sailing speed has been recorded with 3700 rpm of engine in the domestic coast test.