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A proper shape of the trailing edge modification to solve a housing damage problem in a gas turbine power plant
(2021-04-01)
Jansaengsuk, Thodsaphon
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Kaewbumrung, Mongkol
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Busayaporn, Wutthikrai
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Thongsri, Jatuporn
To solve the housing damage problem of a fractured compressor blade (CB) caused by an impact on the inner casing of a gas turbine in the seventh stage (from 15 stages), modifications of the trailing edge (TE) of the CB have been proposed, namely 6.5 mm curved cutting and a combination of 4 mm straight cutting with 6.5 mm curved cutting. The simulation results of the modifications in both aerodynamics variables C<inf>l</inf> and C<inf>d</inf> and the pressure ratio, including structural dynamics such as a normalized power spectrum, frequency, total deformation, equivalent stress, and the safety factor, found that 6.5 mm curved cutting could deliver the aerodynamics and structural dynamics similar to the original CB. This result also overcomes the previous work that proposed 5.0 mm straight cutting. This work also indicates that the operation of a CB gives uneven pressure and temperature, which get higher in the TE area. The slightly modified CB can present the difference in the properties of both the aerodynamics and the structural dynamics. Therefore, any modifications of the TE should be investigated for both properties simultaneously. Finally, the results from this work can be very useful information for the modification of the CB in the housing damage problem of the other rotating types of machinery in a gas turbine power plant.
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A novel ultrasonic cleaning tank developed by harmonic response analysis and computational fluid dynamics
(2020-03-01)
Tangsopa, Worapol
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Thongsri, Jatuporn
The manufacturer of an ultrasonic cleaning tank (UCT) received advise from a customer to seek the cause to why the UCT could not clean their products effectively and develop a novel UCT to replace the conventional model. This UCT had a capacity of 10 L, a frequency of 28 kHz, four horn transducers, and a total power of 200 W. To resolve that problem and respond to customers’ needs, we presented new methods to develop the UCT using the harmonic response analysis (HRA) and computational fluid dynamics (CFD) to simulate the cleaning process which occurred within the UCT based on the actual conditions. Results from the HRA showed that the acoustic pressure in a problematic UCT was low, resulting in a smaller cleaning area, which was consistent with the results from the foil corrosion test, and thus caused the cleaning process to be ineffective. We developed a novel UCT with improved effectiveness by adjusting the design and adding a water circulation system. From the HRA, we were able to design the dimensions of the UTC and position of the transducer to be suitable to increase the acoustic pressure and cleaning area. CFD results enabled us to design proper inlet and outlet shapes, as well as simulate the water flow behavior to find the optimal cleaning condition so the novel UCT had a water circulation system that could eliminate the excess particles.
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Numerical investigation on the performance of suction head in a cleaning process of hard disk drive factory
(2020-02-28)
Khongsin, Jirawat
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Thongsri, Jatuporn
The suction head is a component positioned at the vacuum cleaner’s tip and used to control airflow to eliminate small particles, thus preventing contamination from occurring during the cleaning process at a hard disk drive (HDD) manufacturing factory. At the factory, 2 suction head types (bowl and straight) were used in the cleaning process. From an actual usage, the operators questioned the operating condi-tion’s performance and suitability. In order to seek an answer to the questions, the researchers used computational fluid dynamics (CFD) to simulate airflow and particle trace using the ANSYS Fluent software, the factory’s actual conditions, and a suction distance ranging between 2.5–15 mm. CFD simulation results showed that the bowl type suction head performed better compared to the straight type in every suction range under the exact same operating conditions. Both suction heads performed well at a 5 mm distance between the suction head and cleaning area. Suction performance decreased when the head was positioned closer or farther than the mentioned distance. Apart from applying all results from this research to increase cleaning efficiency in the actual factory, the findings could also be used as basic information for designing new suction head models with higher efficiency than the original model.
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Investigation of the trailing edge modification effect on compressor blade aerodynamics using SST k-ω turbulence model
(2019-04-01)
Kaewbumrung, Mongkol
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Tangsopa, Worapol
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Thongsri, Jatuporn
A gas turbine power plant in Thailand had the problem of compressor blade fracture in Stages 6-8, which was caused by housing damage. This gas turbine has a total of 15 stages. The housing damage reduced the lifetime of blades to an unacceptable level. This article shall report the solution and outcomes. Three-dimensional (3D) compressor blade models in the problematic stages were prepared by a 3D scanning machine to find a solution based on computational fluid dynamics (CFD), and then were completed for simulation by adding Stages 5 and 9 to become a multi-stage axial model. The latter models were modified by trimming the trailing edge by 1-, 5-, and 10-mm. Using ANSYS CFX R19.2 software, the CFD results of the trailing edge modification effect on flow using the shear stress transport (SST) k-ω turbulence model revealed aerodynamics inside the problematic stages both before and after blade modifications. Modifying the blade by 5 mm was suitable, because it had lesser effects on aerodynamic parameters: pressure ratio, drag, and lift coefficients, when compared to the modification of 10 mm. The larger the modification, the greater the effect on aerodynamics. The effects on aerodynamics were intensified when they were modified by 10 mm. The validation of base line blades was conducted for the overall compressor parameters that were compared with the measurable data. These results were accepted and gave positive feedbacks from engineers who practically applied our reports in a real maintenance period of gas turbine.
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Simulation of airflow in a cleanroom to solve contamination problem in an HDD production line
(2018-01-01)
Naosungnoen, Jiranan
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Thongsri, Jatuporn
Contamination that exceeds the specification is one of many causes that contributed to a poor quality product in HDD cleanroom manufacturing process. The purpose of this research was to utilize CFD simulation to study the airflow in a clean room to find out the cause(s) of high contamination and to propose a remedy. The results of the simulation show that some areas in the production line had vortex flow and collected a large number of particles which were similar to the results of actual measurement in that clean room. A particular area, which was a long rectangular area near the middle of the clean room, stretching from one side of the room to the other, showed high particle concentration compared to other areas. To solve this problem, we closed one of the ULPA filters which was an inlet of that area. Subsequent simulation showed that there was less vortex flow and a significant reduction of particle concentration. Our method proved to be able to improve contamination control in a manufacturing clean room.
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Optimum airflow to reduce particle contamination inside welding automation machine of hard disk drive production line
(2015-03-01)
Thongsri, Jatuporn
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Pimsarn, Monsak
Welding automation machine (WAM), used for welding minute components to the head gimbal assembly (HGA) of a hard disk drive (HDD), needs to operate in a strictly clean environment. In today’s HDD factories, to prevent airborne particle contamination to the WAM, Fan Filter Units (FFUs) are installed on top of it to supply clean air and blow away outside airborne micro particles, keeping the microenvironment clean. Furthermore, the mass of the clean air should also carry away harmful particles generated inside the microenvironment. In this research, numerical simulation of airflow inside a WAM was performed in order to verify these cleaning functions of the airflow. A transition shear stress transport turbulence model was employed to simulate airflow from the FFUs through and out of the microenvironment. The simulation results showed that the airflow from the FFUs truly performs the two cleaning functions as intended. Moreover, they also revealed that the optimum air speed, the speed resulting in the lowest particle counts, is in the range of 0.35–0.55 m/s. Our findings can be useful for developers who may use FFUs to reduce particle counts in the environment of other types of industrial machinery.
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Simulated trajectories of particles and the number of particles trapped by the circulating filter in a hard disk drive
(2014-01-01)
Thongsri, Jatuporn
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Pongkom, Vana
The particle trajectories and the number of them trapped by circulating filter of a 2.5 inch dual platter hard disk drive (HDD) were numerically investigated using a transition shear stress transport turbulence model (transition SST). Four head gimbal assemblies (HGAs) were placed at the outer diameter positions where tiny particles of alumina were released. The simulation revealed the results of airflow, particle trajectories and efficiency of a circulating filter. This result can be applied as fundamental information to design HDD layout in order to reduce its contamination. © (2014) Trans Tech Publications, Switzerland.
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Successful simulation of airflow in the microenvironment of an assembly automation machine and its implication
(2014-01-01)
Thongsri, Jatuporn
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Khaokom, Adisorn
Today, the hard disk drive (HDD) industry is using assembly automation machine (AAM) to construct head stack assembly (HSA) from smaller parts. AAM needs to operate in a clean environment with very low particle counts. To achieve this end, fan filter Unit (FFU) is used to supply purified air into the environment by filtering out airborne particles from recirculating air. In this study, we investigated numerically the airflow induced by FFUs inside a microenvironment that houses an AAM in an HDD factory. The boundary conditions chosen for simulation were directly derived from the real ambient conditions in this HDD factory. We found that the FFUs not only filter out airborne particles from the air supplied into the microenvironment but also act as a particle blocker, pushing away the nearby particles in the air surrounding the openings of the microenvironment. The findings from this study can be applied to cases where other kinds of machinery need to be protected from airborne particles. © (2014) Trans Tech Publications, Switzerland.
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Numerical investigation of airflow pattern inside environmental chamber
(2014-01-01)
Thongsri, Jatuporn
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Suksawaeng, Wutthinan
In industrial hard disk drive research and development laboratories, an environmental chamber is normally used to perform a mechanical verification test of Head Gimbal Assembly (HGA). It is very important to verify that the airflow pattern in the chamber is comparable to that in a real hard disk drive. Hence, we applied a transition shear stress transportation turbulence model (transition SST), one of the robust mathematical models in computer fluid dynamics, to simulate the airflow behavior inside both an environmental chamber and a hard disk drive (HDD). We found that, overall, the two patterns of airflow were not comparable at all. The air velocity vectors around the HGA in VENA were smaller than that in HDD. The reason for this is likely to be that there was more space between the top cover of the chamber and the platter than the space between the top cover of the hard disk drive and its platter. © (2014) Trans Tech Publications, Switzerland.

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