Authors:
Fazlar Rahman; A S M Mohaiminul Mim, Md. Zahid Hasan Pages: 83 - 92 Abstract: High numbers of workplace casualties and injuries are reported each year in Bangladesh due to explosion of the boiler in the rice husking mills, as well as other industries including garments factories. Rice husking mills are using locally made steam boilers, which are fabricated of steel plate obtained from the ship breaking yard and not equipped with standard safety devices and fittings. The motivation of this work is to find the causes of explosion of those boilers and provide some modifications to reduce workplace casualties. In this regard, some rice husking mills in the rural area of Bangladesh are inspected to evaluate the working and operating condition of the boilers. The mechanical properties of steel plate obtained from the ship breaking yard is found by tensile test in UTM and those mechanical properties are used in numerical analysis of the boiler, which is currently operating in the rice husking mills and fabricated locally from same source of steel plate. The FEA tool ANSYS workbench is used in numerical analysis of the boiler to evaluate maximum working stress due to thermal and static pressure load, which is found below the yield strength of the test specimen. From the instantaneous pattern of explosion in all boiler incidents and result of the numerical analysis, it is concluded that strength of steel plates obtained from the ship breaking yards is not the cause of boiler explosion, operational malfunction and lack of safety measures are the main causes of boiler explosion in Bangladesh especially in the rice husking mills. To improve safety measures, modification cost of the boiler is evaluated by modifying a locally fabricated steam boiler, which is also made of same source of steel plate and currently operating in the rice husking mill. The modification cost to install safety devices and fittings is found about Tk. 25,000 ($300), which is easily affordable by rice husking mill. Finally, some steps are recommended to reduce boiler explosion and concluded that steel plates obtained from the ship breaking yards have enough mechanical strength and can be used to fabricate low-pressure boilers. PubDate: 2018-09-17 DOI: 10.12691/ajme-6-3-1 Issue No:Vol. 6, No. 3 (2018)

Authors:
Hadi Nourghassemi; Hassan Ghassemi, Hamidreza Taghva Pages: 93 - 97 Abstract: This paper presents the hydrodynamic results of the two stepped planing hull by numerical software solver. Time-averaged Navier-Stokes equations are coupled with the standard k-ε turbulence model, and volume of fluid equations are solved to simulate transient turbulent free surface flow surrounding the hull by ANSYS-CFX. In order to predict the motion of the vessel, equations of two degrees of freedom for rigid body are coupled with governing equations of fluid flow. In order to validate the numerical model, the obtained numerical results are compared with the available experimental data. The numerical results obtained for drag, dynamic trim, rising of centre of gravity (CG) and the pressure distribution on the body at different speeds and different heights of the applied steps are presented and discussed. PubDate: 2018-11-02 DOI: 10.12691/ajme-6-3-2 Issue No:Vol. 6, No. 3 (2018)