• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1900-1905
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• 2007

A micro cyclone combustor was developed to be used as a heat source of thermoelectric power generator (TPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately. The mixing and flow characteristics in the combustor were investigated numerically. The global equivalence ratio (${\Phi}$), defined using the fuel and air flow rates, was introduced to examine the flow features of the combustor. The mixing of fuel and air inside the combustor could be well understood using the fuel concentration distribution. It was found that the weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$ < 1.0. In addition, it was found that small regions that have a negative axial velocity exist near the fuel injection ports. It is assumed that these negative axial velocity regions can stabilize a flame inside the micro cyclone combustor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.39-45
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• 2003

As the size of a combustor decreases to a MEMS scale, heat loss increases and becomes a dominant effect on the performance of the devices. Existing models, however, are not adequate to predict the heat transfer and combustion processes in such small scales. In the present study, a semi-empirical model to calculate heat loss from a micro combustor is described. The model derives heat transfer coefficients that best fits the heat loss characteristics of a micro combustor that is represented by transient pressure record after combustion is completed. From conservation of energy equation applied to the burned gas inside the combustor, a relationship between pressure and heat transfer is reduced. Two models for heat transfer coefficients were tested; a constant and first order polynomial of temperature with its coefficients determined from fitting with measurements. The model was tested on a problem of cooling process of burnt gas in a micro combustor and comparison with measurements showed good agreements. The heat transfer coefficients were used for combustion calculation in a micro vessel. The results showed the dependence of flame speed on the scale of the chamber through enhanced heat loss.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.139-144
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• 2007

A micro cyclone combustor was developed to be used as a component of mobile power generator (MPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately to prevent a flash-back. The flame shape stabilized inside the micro cyclone combustor was visualized experimentally and the flow field and the combustion characteristics of the combustor were investigated numerically. The global equivalence ratio (${\Phi}$), defined using the fuel and air flow rates, was introduced to examine the overall flow and flame features of the combustor. The flame stabilization mechanism could be well understood using the velocity distribution inside the combustor. For only non-reacting case, it was found that a weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$ < 1.0. It was also found that small regions that have a negative axial velocity exist near the fuel injection ports for both of non-reacting and reacting case. It was identify that a flame front was stabilized at the negative axial velocity regions near the fuel injection ports.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.1042-1047
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• 2007

A micro cyclone combustor was developed to be used as a heat source of thermoelectric power generator (TPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately. The mixing and flow characteristics in the combustor were investigated numerically. The global equivalence ratio ($\Phi$), defined using the fuel and air flow rates, was introduced to examine the flow features of the combustor. The mixing of fuel and air inside the combustor could be well understood using the fuel concentration distribution. It was found that the weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$<1.0. In addition, it was found that small regions that have a negative axial velocity exist near the fuel injection ports. It is assumed that these negative axial velocity regions can stabilize a flame inside the micro cyclone combustor.

• Journal of ILASS-Korea
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• v.13 no.3
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• pp.149-155
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• 2008

An experimental study was performed to understand spray characteristics of the rotary atomizer for the slinger combustor. In this fuel injection system, fuel is injected and atomized in the combustor by centrifugal forces to engine shaft. The experimental apparatus consists of a high speed rotational spindle, rotary atomizer, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA (phase Doppler particle analyzer), and spray was visualized by using high speed camera and Nd:Yag laser-based flash photography. From the test results, the droplet size (SMD) is largely affected by rotational speed, mass flow rate and the number of orifice. As the experimental results, we could understand the spray characteristics of the rotary atomizer for the slinger combustor and obtain the optimum shape of the rotary atomizer which is suitable for the small gas turbine engine.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.840-845
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• 2001

Development of a small gas-turbine combustor for 100kW class APU(Auxiliary Power Unit) has been performed. This combustor is a reverse-annular type and has a tangential swirler in the liner head to improve the fuel/air mixing and flame stability. Three main and three pilot fuel injectors of the simplex pressure-swirl type are used. The performance target at the design condition includes a turbine inlet temperature of 1170K, a combustion efficiency of 99%, a pattern factor of 30%, and an engine durability of 3000 hours. Under developing the combustor, we conducted performance test of our first prototype(TS1) with some variants. As a result of the test, the performance targets of the combustor are satisfied except that the pattern factor is about 4% higher than target value. So, we redesigned the second prototype(TS2) and conduct performance test with the critical focus on pattern factor and exit mean temperature. We adopted TS2 four variant to check the improvement of pattern factor. As the result, the pattern factors of several variants were satisfied with the performance target. Finally, We chose the TS2A variant as a final combustor for our APU model.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.155-158
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• 2008

A practical modeling approach of a small slinger combustor is proposed and a 2-dimensional axisymmetric computational model is developed. Based on numerical results from the full 3-dimensional configuration, model reduction is achieved toward 2-dimensional axisymmetric configuration. By simplifying the complex model, computing time can be significantly reduced and it makes easy to find effects of geometry modification. Numerical results show that the flow characteristic of 2-D model is quite similar to that of the 3-D configuration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.45-48
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• 2008

Micro power generators have been studying to provide high power that micro systems require. Micro power generators need micro combustor. Swiss-roll combustor has been studied about scale, geometry, material. From previous study experiments have shown that swiss-roll combustors require thin walls with low thermal conductivity for maximum performance at small scales. In this work, polyimide combustors with low thermal conductivity and thin thickness are built and tested.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.3
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• pp.61-68
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• 2010

A small high altitude test facility has been developed to investigate ignition performance of a small gas-turbine combustor under high altitude conditions. Supersonic diffusers and a heat exchanger were used to perform a low pressure and a low temperature condition, respectively. Experimental results showed that the low pressure environment could be controlled by upstream pressure of primary nozzle flow and low temperature environment by mixture ratio of cooled air and ambient air. Ignition performance tests were performed to verify the performance of the facility under simulated high altitude conditions. Conclusively, it was proven that the test facility could be used for ignition performance test of a small gas-turbine combustor under high altitude condition of approximately 6,100m.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.598-606
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• 2022

With the advancement of industry, the use of various sustainable energy sources and solutions to problems affecting the environment are being actively requested. From this point of view, it is intended to directly burn unused biogas to use it as energy and to solve environmental problems such as greenhouse gases. In this study, a new type of cavity matrix combustor capable of low-emission complete combustion without complex facilities such as separation or purification of biogas produced in small and medium-sized facilities was proposed, and CFD numerical calculation was performed to understand the performance characteristics of this combustor. The cavity matrix combustor consists of a burner with a rectangular porous microwave receptor at the center inside a 3D cavity that maintains a rectangular parallelepiped shape composed of a porous plate that can store heat in the combustor chamber. As a result of numerical calculation, the biogas supplied to the inlet of the combustor is converted to CO and H₂, which are intermediate products, on the surface of the 3D matrix porous burner. And then the optimal combustion process was achieved through complete combustion into CO₂ and H₂O due to increased combustibility by receiving heat energy from the microwave heating receptor.