• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.4
• /
• pp.10-18
• /
• 2007

A tested micro axial-type turbine consists of two stages and its mean radius of rotor flow passage is 8.4 mm. This turbine could be applied to a driver of micro power system, and its rotational speed in the unloaded state reaches to 100,000 RPM. The performance of this system is sensitive depending on the blade angles of the rotor and stator because it is operated in a low partial admission rate, so a performance test is conducted through measuring the specific output power and the net specific output torque with various blade angles on the nozzle, stator and rotor. The experimental results show that the net specific output torque is varied by 15% by changing the rotor blade angle, and the optimal incidence angle is about $10.3^{\circ}$.

• Tribology and Lubricants
• /
• v.12 no.4
• /
• pp.28-34
• /
• 1996

The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.11
• /
• pp.1591-1602
• /
• 1998

Simple spanwise distribution models of deviation angle and pressure loss coefficient due to the tip leakage flow are formulated for use in association with the streamline curvature method as a flow analysis. Combining these new models with the previous deviation and loss models due to secondary flow, a robust streamline curvature method is established for flow analysis of single-stage, subsonic axial turbines with wide ranges of turning angle, aspect ratio and blading type. At the exit from rotor rows, the flow variables are mixed radially according to a spanwise transport equation. The proposed streamline curvature method is tested against a forced vortex type turbine as well as a free vortex type one. The results show that the spanwise variations of flow angle, axial velocity and loss coefficients at rotor exit are predicted with good accuracy, being comparable to a steady three-dimensional Navier-Stokes analysis. This simple and fast flow analysis is found to be very useful for the turbine design at the initial design phase.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1996.04b
• /
• pp.86-93
• /
• 1996

The lubrication characteristics of high-speed ball bearings has been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flowrates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 303 kgf axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.5
• /
• pp.78-82
• /
• 2014

This paper describes a brief aerodynamic design procedure of multi-stage axial turbine. The design procedure was established including one dimensional scratch design, through flow analysis with empirical correlations, two dimensional airfoil design and three dimensional airfoil stacking. Detailed aerodynamic performance assessment was done with full three dimensional CFD method at the design and off design conditions to construct turbine performance map. With the present method, aerodynamic design procedure of 1st and 2nd stages of high pressure turbine for 10,000lbf class turbofan engine was introduced.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.147-154
• /
• 2010

The world is gradually running short of fossil fuel. Currently, the role of wind turbine is attracting great attention from all over the world. The objective of this study is to investigate blades of Vertical-axial wind turbine (VAWT) for optimum design using the CFD from the aerodynamics point of view. Because one of the performance of wind turbine depends on shape of blades, the study of comparing one gyro mill type blade and a modified one was carried out. Using the results of computation, we calculated and compared RPM for both models at same wind velocity. And we calculated angular acceleration and moment of inertia to find torque in every time-step. And the pressure contour and velocity profile around the blade were analyzed Also, this study is performed to calculate the wake effect.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2001.04a
• /
• pp.59-62
• /
• 2001

An axial-type turbine design technology is developed. In order to design one-stage turbine, preliminary design method is applied, and then design parameters are chosen after analyzing the gas properties within the turbine passage using the streamline curvature method. Stator blade is designed using C4 Profile, and rotor blade is designed using shape parameters. The output power is measured with various RPM and input power. The experimental result shows that the output power is proportionally decreased with the negative incidence angle.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.8
• /
• pp.1173-1182
• /
• 1998

A throughflow analysis program for axial flow turbines is constructed, which can handle not only the two-dimensional multi-streamline (streamline curvature) method but also the one-dimensional mean line method. Calculations are performed for single stage and multi-stage axial flowturbines. For a wide operating range, the performance and flow field calculated by the present streamline curvature method are close enough to the test data. It is also revealed for the single stage turbine that the present analysis leads to far better correspondence with the experiment than other researchers" throughflow analyses. A special focus is put on the comparison of the results between the streamline curvature analysis and the mean line analysis. It is found that the mean line analysis can not predict the performance for highly off-designed conditions as accurately as the streamline curvature method, which shows the importance of considering the spanwise variation of loss and flow.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.537-540
• /
• 2002

Flow through turbomachinery has a very complex structure and is intrinsically unsteady. Especially, recent design trend to turbomachinery with short axial spacing makes the flow extremely complex due to the interaction between stator and rotor. Therefore, it is very necessary to clearly understand the complex flow structure to obtain the high efficiency turbomachinery. So, in this paper, the effects of axial spacing on the unsteady secondary flow performance in the one stage turbine are investigated by three-dimensional unsteady flow analysis. The three-dimensional solver is parallelized using domain decomposition and Message Passing Interface(MPI) standard to overcome the limitation of memory and the CPU time in three-dimensional unsteady calculation. A sliding mesh interface approach has been implemented to exchange flow information between blade rows.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.9
• /
• pp.1292-1301
• /
• 2002

An experimental study of turbine performance is conducted with various incidence angles on a rotating turbine rotor. 5 different incidence angles are applied from -17$^{\circ}$to 13$^{\circ}$with 7.5$^{\circ}$gaps. In order to precisely set up the incidence angles at the rotor inlet, 5 turbine discs are manufactured with the different fir tree section. Total-to-total efficiencies are obtained on the several off-design points with considering the exit total pressure, which is meas fred at 12 locations between the hub and casing using a pressure rake. The degree of reaction is 0.373 at the mean radius, and Reynolds number based on the rotor chord is 0.86$\times$10$^{5}$ at the turbine inlet on the design point experiment. The experiment on a single-stage turbine is conducted at the low-pressure and low-speed state, but it is sufficient to consider the blade loading effect due to the rotating apparatus even though the total pressure loss at the exit is increased proportionally to the turbine output power. The experimental results recommend 6$^{\circ}$as an optimum incidence angle on the turbine blade design. The total-to-total efficiency is steeply decreased when the incidence angle is over $\pm$9$^{\circ}$ from the optimum incidence angle. In the range of less than -10$^{\circ}$incidence angle, 7.5$^{\circ}$ reduction of incidence angle generates 15% decrease of total-to-total efficiency. This result is obtained on the same rotor blade by changing only the rotational speed to minimize the effect of profile and secondary flow loss in the passage. Experimental results show that the change rate of total-to-total efficiency according to the incidence angle change is unchanged although the turbine operates at the off-design condition.