• 유체기계공업학회:학술대회논문집
• /
• 2005.12a
• /
• pp.819-824
• /
• 2005

Recently, micro hydropower attracts attention because of its clean, renewable and abundant energy resources to develop. However, suitable turbine type is not normalized yet in the range of micro hydropower and it is necessary to study for the effective turbine type. Moreover, relatively high manufacturing cost by the complex structure of the turbine is the highest barrier for developing the micro hydropower turbine. Therefore, a cross-flow turbine is proposed for micro-hydropower in this study because of its simple structure and high possibility of applying to low head. The purpose of this study is to further simplify the turbine structure and improve the performance, A guide vane is removed and the runner chamber is made compact using a new air supply method. The results show that the efficiency of the turbine is improved in a wide operating range and the size of the turbine is remarkably reduced.

• Nuclear Engineering and Technology
• /
• v.55 no.7
• /
• pp.2697-2711
• /
• 2023

In this study, the validity of reducing the number of gas turbine stages designed for a nitrogen Brayton cycle coupled to a sodium-cooled fast reactor was assessed. The turbine performance was evaluated through computational fluid dynamics (CFD) simulations under different off-design conditions controlled by a reduced flow rate and reduced rotational speed. Two different multistage gas turbines designed to extract almost the same specific work were selected: two- and three-stage turbines (mid-span stage loading coefficient: 1.23 and 1.0, respectively). Real gas properties were considered in the CFD simulation in accordance with the Peng-Robinson's equation of state. According to the CFD results, the off-design performance of the two-stage turbine is comparable to that of the three-stage turbine. Moreover, compared to the three-stage turbine, the two-stage turbine generates less entropy across the shock wave. The results indicate that under both design and off-design conditions, increasing the stage loading coefficient for a fewer number of turbine stages is effective in terms of performance and size. Furthermore, the Ellipse law can be used to assess off-design performance and increasing exponent of the expansion ratio term better predicts the off-design performance with a few stages (two or three).

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.771-774
• /
• 2007

Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed with hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of the syngas to the performance of a gas turbine in a combined cycle power plant. For this purpose, a commercial gas turbine is selected and its performance characteristics are analyzed with syngas. It is found that different heating values of those fuels and chemical compositions in their combustion gases are the causes in the different performance characteristics. Also, Changing of turbine inlet Mass flow lead to change the turbine matching point, in the event the pressure ratio is changed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.2
• /
• pp.42-48
• /
• 1994

Turbocharging is one of the best methods to improve the performance of diesel engines, because of its merits,-power ratio, fuel consumption and exhaust emissions. Most of them in small and medium diesel engines have adopted the pulse turbocharging method with twin entry vaneless radial turbines to maximize the energy utility of exhaust gas. This method requires the high performance of turbine under unsteady flow, and also the matching between turbine and diesel engine is most important. However, it is difficult to match properly between them. Because the steady flow data are usually used for it. Accordingly, it is necessary to catch the characteristics of turbine performance correctly over the wide range of the operation conditions under unsteady flow. In this paper, the characteristics of turbine performance under unsteady flow are represented at varying conditions, such as inlet pressure amplitude, turbine speed and frequence.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.2
• /
• pp.296-303
• /
• 2006

Recently, micro hydropower attracts attention because of its clean. renewable and abundant energy resources to develop. However, suitable turbine type is not normalized yet in the range of micro hydropower and it is necessary to study for the effective turbine type. Moreover, relatively high manufacturing cost by the complex structure of the turbine is the highest barrier for developing the micro hydropower turbine. Therefore a cross-flow turbine is proposed for micro-hydropower in this study because of its simple structure and high possibility of applying to low head. The purpose of this study Is to further optimize the turbine structure and improve the performance. A guide vane is removed and the runner chamber is made compact using a new air supply method. The results show that the efficiency of the turbine is improved in a wide operating range and the size of the turbine is remarkably reduced.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.1
• /
• pp.1-6
• /
• 2008

Performance test of the 30-ton class liquid rocket engine turbopump turbine has been conducted using high pressure cold air. Overall performance of the two kinds of turbine rotors - rotor with knife-edged L.E blades and with rounded L.E blades - has been measured for various rotational speed and turbine pressure ratio. The effect of rotational speed and turbine pressure ratio on the turbine axial force behavior also has been measured in parallel. Test results have revealed that the efficiency of knife edged L.E. turbine is a little bit higher than that of rounded L.E. turbine. The axial force of the turbine varied linearly with respect to rotational speed and its magnitude largely depended on turbine pressure ratio.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1070_1071
• /
• 2009

Recently, small hydropower attracts attention because of its clean, renewable and abundant energy resources to develop. Therefore, a cross-flow hydraulic turbine is proposed for small hydropower development in this study. The turbine‘s simple structure and high possibility of applying to the sites of relatively low effective head and large flow rate can be advantages for the introduction of the small hydropower development. The purpose of this study is not only to investigate the effects of air layer in the turbine chamber on the performance and internal flow of the cross-flow turbine, but also to suggest a newly developed air supply method. CFD analysis for the performance and internal flow of the turbine is conducted by an unsteady state calculation using a two-phase flow model in order to embody the air layer effect on the turbine performance effectively. The result shows that air layer effect on the performance of the turbine is considerable. The air layer located in the turbine runner passage plays the role of preventing a shock loss in the runner axis and suppressing a recirculation flow in the runner. The location of air suction hole on the chamber wall is very important factor for the performance improvement. Moreover, the ratio between air from suction pipe and water from turbine inlet is also significant factor of the turbine performance.

• Journal of Advanced Research in Ocean Engineering
• /
• v.1 no.2
• /
• pp.73-84
• /
• 2015

The turbine is one of the most important components in the tidal current power device which can convert current flow to rotational energy. Generally, a tidal turbine has two or three blades that are subjected to hydrodynamic loads. The blades are continuously deformed by various incoming flow velocities. Depending on the velocities, blade size, and material, the deformation rates would be different that could affect the power production rate as well as turbine performance. Surely deformed blades would decrease the performance of the turbine. However, most studies of turbine performance have been carried out without considerations on the blade deformation. The power estimation and analysis should consider the deformed blade shape for accurate output power. This paper describes a fluid-structure interaction (FSI) analysis conducted using computational fluid dynamics (CFD) and the finite element method (FEM) to estimate practical turbine performance. The loss of turbine efficiency was calculated for a deformed blade that decreased by 2.2% with maximum deformation of 216mm at the blade tip. As a result of the study, principal causes of power loss induced by blade deformation were analysed and summarised in this paper.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.2
• /
• pp.78-86
• /
• 2006

This paper presents the performance test result of the 30-ton class turbopump turbine. Test has been conducted using high pressure cold air, The turbine overall performance has been measured for various pressure ratio and rotational speed settings. The nozzle-rotor clearance effect on turbine performance also has been tested for the four kinds of the nozzle-rotor clearance values. We found that turbine efficiency rated 51.1% at its design velocity ratio and pressure ratio of 13.5. We also found that turbine efficiency can be increased by 3.5% for approximately 1mm decrement of the nozzle-rotor clearance from its nominal value.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.5
• /
• pp.514-521
• /
• 2007

There has been considerable interest recently in the topic of renewable energy. This is primarily due to concerns about environmental impacts. Moreover, fluctuating and rising oil prices, increases in demand, supply uncertainties and other factors have led to increased calls for alternative energy sources. Small hydropower, especially using water supply system, attracts high attentions because of relatively lower cost and smaller space requirements to construct the plant. Moreover. newly developed positive displacement turbine has high acceptability for the system. Therefore, the purpose of this study is focused on the examination of the performance characteristics and proposition of a optimum design method of the turbine for the improvement of the performance. The results show that newly proposed optimum design method for the turbine has high accuracy of performance prediction and good applicability for the performance improvement of the turbine.