• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.4
• /
• pp.344-350
• /
• 2013

The purpose of this study is to examine the structural stability of a low speed 200 W class gyromill type vertical axis wind turbine system. For the analysis, a commercial code is adopted. The pressure distribution on the rotor blade surface is examined in detail. In order to perform unidirectional FSI(Fluid-Structure Interaction) analysis, the pressure resulted from CFD analysis has been mapped on the surface of wind turbine as load condition. The rotational speed and gravitational force of wind turbine are also considered. The results of FSI analysis show that the wind turbine reveals an enough structural margin. The maximum structural displacement occurs at trailing edge of blade and the maximum stress occurs at the strut.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.4
• /
• pp.379-384
• /
• 2014

The most critical rotating parts of a gas turbine engine are turbine blades and disc, given that they must operate under severe conditions such as high turbine inlet temperature, high speeds, and high compression ratios. Owing to theses operating conditions and high rotational speed energy, some failures caused by turbine disks and blades are categorized into catastrophic and critical, respectively. To maximize the margin of structural integrity, we aim to optimize the vulnerable area of disc-blade interface region. Then, to check the robustness of the obtained optimized solution, we evaluated structural reliability under uncertainties such as dimensional tolerance and fatigue life variant. The results highlighted the necessity for and limitations of optimization which is one of deterministic methods, and pointed out the requirement for introducing reliability-based design optimization which is one of stochastic methods. Thermal-structural coupled-filed analysis and contact analysis are performed for them.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.7
• /
• pp.80-86
• /
• 2019

As computer performance improves, research using deep learning are being actively carried out in various fields. Recently, deep learning technology has been applying to the safety evaluation for structures. In particular, the internal blades of a turbine structure requires experienced experts and considerable time to detect surface damages because of the difficulty of separation of the blades from the structure and the dark environmental condition. This study proposes a Faster R-CNN deep learning model that can detect surface damages on the internal blades, which is one of the primary elements of the turbine structure. The deep learning model was trained using image data with dent and punch damages. The image data was also expanded using image filtering and image data generator techniques. As a result, the deep learning model showed 96.1% accuracy, 95.3% recall, and 96% precision. The value of the recall means that the proposed deep learning model could not detect the blade damages for 4.7%. The performance of the proposed damage detection system can be further improved by collecting and extending damage images in various environments, and finally it can be applicable for turbine engine maintenance.

• Proceedings of the Korean Reliability Society Conference
• /
• 2002.06a
• /
• pp.199-204
• /
• 2002

본 연구에서는 저압 증기 터빈블레이드의 안전성 확보를 위하여 작용응력 및 강도의 변동성을 고려한 확률론적 해석을 수행하였다. 정상상태에서 작용응력은 이론 및 유한요소해석에 의해서 얻을 수 있으며, 최대 von-Mises 응력은 215.4MPa이다. 회전굽힘 하중하에서의 피로한도는 응력비 R= -1에서 계단식 시험법을 이용하여 구하였으며, 이의 확률론적 특성에 가장 적합한 분포는 3 모수 와이블 분포이다. 그리고 신뢰성에 미치는 다양한 인자들의 영향은 영향계수(sensitivity factor)를 이용하여 정량적으로 평가하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.12
• /
• pp.1281-1288
• /
• 2009

Variation of dynamic characteristics of a low pressure turbine blade with crack length is studied in this paper via both experiments and finite element model. Since most of the turbine blades used in domestic power plants are imported from abroad, it is necessary to understand their dynamic behavior in advance. When experimentally obtained natural frequencies and mode shapes are compared with those from FEM results, they are close to each other in their magnitude. Then, it is more feasible to use finite element model for analyzing the dynamic characteristics of a blade under various operation conditions (rotation speed, temperature, etc) as well as with a crack in the blade.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.181-184
• /
• 2008

Austenitic stainless steel is used as high temperature components such as gas turbine blade and disk because of its good thermal resistance. In the present investigation, tensile and low cycle fatigue behavior of 316 stainless steel was studied at wide temperature range $20^{\circ}C{\sim}750^{\circ}C$. In the tensile tests, it was shown that elastic modulus, yield strength, ultimate tensile strength decreases when temperature increased. The effect on fatigue failure of the parameters such as plastic strain amplitude and plastic strain energy density was also investigated. With the experimental results, a structural analysis of turbine blades of 316 stainless steel were carried out.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.185-191
• /
• 2008

The aerodynamic losses so attributed to the endwall - usually termed secondary flow losses or secondary losses - can be as high as 30$\sim$50% of the total aerodynamic losses in a blade or stator row. Inlet guide vanes, with lower total turning and higher convergence ratios, will have smaller secondary losses, amounting to as much as 20% of total loss for an inlet stator row. These are important part for improving a turbine efficiency. The present study deals with a leading edge chamfer groove on a wing-body to investigate the vortex generation and characteristics of a horseshoe vortex with the installed height, and depth of the groove. The current study is investigated with $FLUENT^{TM}$.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.6
• /
• pp.609-617
• /
• 2014

Even though the variable pitch control of a wind turbine blade is known as an effective component for power control over the rated wind speed, it has limited applicability to small wind turbines because of its relatively high cost on the price of small wind turbine. Instead, stall control is generally applied in the blade design without any additional cost. However, stall delay can frequently be caused by high turbulence around the turbine blade, and it can produce control failures through excessive rotational speed and overpowering the electrical generator. Therefore, a passive pitch control module should be considered, where the pitch moves with the aerodynamic forces of the blade and returns by the elastic restoring force. In this study, a method to calculate the pitch moment, torque, and thrust based on the lift and drag of the rotating blade wing was demonstrated, and several effective wing shapes were reviewed based on these forces. Their characteristics will be estimated with variable wind speed and be utilized as basic data for the design of the passive pitch control module.

• Composites Research
• /
• v.28 no.3
• /
• pp.104-111
• /
• 2015

In this work, a structural design on 500W class horizontal axis wind turbine blade using natural-fibre composite is performed. The structural design result of flax composite blade is compared with the result of glass composite blade. The structural design of the wind turbine blade is carried out using the simplified methods such as the netting rule and the rule of mixture. The structural safety of the designed blade structure is investigated through the various load cases, stress, deformation and buckling analyses using the commercial FEM. The structural test of the manufactured prototype blade was performed to confirm the structural analysis results including strains, natural frequencies and deformations. According to the comparison results, it was confirmed that the analysis results are well agreed with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.4
• /
• pp.289-309
• /
• 2014

A rotor blade is an important device that converts kinetic energy of wind into mechanical energy. Rotor blades affect the power performance, energy conversion efficiency, and loading and dynamic stability of wind turbines. Therefore, considering the characteristics of a wind turbine system is important for achieving optimal blade design. This study examined the general blade design procedure for a wind turbine system and aero-structure design results for a 2-MW class wind turbine blade (KR40.1b). As suggested above, a rotor blade cannot be designed independently, because its ultimate and fatigue loads are highly dependent on system operating conditions. Thus, a reference 2-MW wind turbine system was also developed for the system integrated load calculations. All calculations were performed in accordance with IEC 61400-1 and the KR guidelines for wind turbines.