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Nu Rhahida Arini
Politeknik Elektronika Negeri Surabaya, Indonesia
Computer Science & IT

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Journal : EMITTER International Journal of Engineering Technology

 1 
A Technique For Lock-In Prediction On A Fluid Structure Interaction Of Naca 0012 Foil With High Re Nu Rhahida Arini; Stephen R. Turnock; Mingyi Tan
EMITTER International Journal of Engineering Technology Vol 8 No 2 (2020)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v8i2.543

Abstract

A numerical lock-in prediction technique of a NACA 0012 hydrofoil, immersed in a flow having a Re of 3.07x106 is proposed in this paper. The technique observes the foil’s response as part of a fluid-structure interaction analysis. The response is modelled by foil’s vibration which is represented by spring and damper components. The technique identifies and predicts the foil’s lock-in when it vibrates. The prediction is examined using the Phase Averaged Method which employs the Hilbert Transform Method. The aim of this paper is to propose a numerical way to identify a lock-in condition experienced by a NACA 0012 foil in a high Reynolds number flow. The foil’s mechanical properties are selected and its motions are restricted in two modes which are in the pitch and heave directions. The rotational and transverse lock-in modes are identified in the model. The existence of lock-in is verified using pressure distribution plot, the history of trailing edge displacement and fluid regime capture. The history of total force coefficients is also shown to justify the result. The result shows that the technique can predict reliably the lock-in condition on the foil’s interaction. Three main fluid induced vibration frequencies are generated in the interaction. None of them are close to natural frequency of the foil and lock-in is apparently not found in the typical operational condition.
Thermal Analysis of Solar Air Heater with Ventilator Turbine and Fins Arrad Ghani Safitra; Lohdy Diana; Denny Muhammad Agil; Julfan Hafiz Fareza; Nu Rhahida Arini
EMITTER International Journal of Engineering Technology Vol 8 No 2 (2020)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v8i2.584

Abstract

Solar air heater (SAH) is a renewable energy application for the drying process. SAH has a challenge to produce high performance under uncertain weather. The performance of SAH can be enhanced by providing the absorber plate by adding the fins. This study aims to evaluate the thermal performance of SAH with rectangular fins SAH at low air velocity. This study compares the performance of SAH without fins and SAH with rectangular fins. Two variations of a tilt angle of SAH are 0° and 30° which are observed in this study. The SAH uses a ventilator turbine to suck air into the collector box. The air velocity is 0.01 m/s. The method is experimental. The SAH is tested under real condition from 9 a.m. to 4 p.m. The measurement tools consist of a pyranometer, an anemometer, a temperature sensor in the inlet section, 3 sensors in the absorber plate, a sensor in the outlet section, 6 temperature sensors in the drying cabinet. The result showed the thermal efficiency of SAH with rectangular fins is 29.67 % higher than SAH without fins at 0˚ tilt of angle at noon. The thermal efficiency of SAH with rectangular fins is 25.26 % higher than that of without fins at 30˚ tilt of angle at noon.
The Development of A Reliability Evaluation Application for Power Plant Steam Turbine Vibrations to Predict Its Failure Moch. Faqih; Nu Rhahida Arini; Hendrik Elvian Gayuh Prasetya
EMITTER International Journal of Engineering Technology Vol 9 No 2 (2021)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v9i2.619

Abstract

A steam turbine is the most critical component in a thermal power plant. Due to its crucial function, it should be maintained to be able to operate without failure. This paper aims to develop an application that can be used to analyze the reliability and synchronization of vibrations in a single evaluation through the application. The application is helpful to decide the proper time the maintenance should be performed in order to provide a better maintenance strategy. In this paper, the application was used to make an ease in evaluating the reliability and vibration of a 670 MW power plant steam turbine. The reliability was analyzed by qualitative and quantitative methods. The vibration evaluation using Fast Fourier Transform (FFT) was done by diagnosing the failure symptoms from vibration spectrum. The analysis of synchronization of vibrations conducted by comparing the vibration frequency and the natural frequency of the system which can be calculated easily using the application. The algorithm program of both evaluations was built using GNU Octave software to make a friendly user interface. From the evaluation result, the most critical components of the steam turbine are coupling, labyrinth seals, bearing, diaphragm, turbine control valve, and turbine stop valve. The maintenance interval based on the expected reliability of 90% produces the highest reliability improvement. Based on the vibration analysis, there is no failure symptoms detected in the turbine bearings. Furthermore, the dominant frequencies of vibration are distant from the natural frequency. Therefore, the steam turbine condition is acceptable to operate.
Co-Authors Arrad Ghani Safitra Denny Muhammad Agil Hendrik Elvian Gayuh Prasetya, Hendrik Elvian Julfan Hafiz Fareza Lohdy Diana Mingyi Tan Moch. Faqih Stephen R. Turnock