Engineering and Technology Journal

The newest class of heat transfer improvement is accomplished by using hybrid Nano-fluids. Therefore, the heat transfer and pressure drop of a mixture of Iron oxide (Fe3O4) and Magnesium oxide (MgO) nanoparticles suspended into the base fluid under a turbulent regime through a plain and wavy tube are computed employing commercial software ANSYS Fluent. A mixture of Fe3O4 and MgO nanoparticles in pure water is considered a brand-new type of hybrid Nano-fluid for boosting heat transfer. The simulation procedures were performed utilizing the single and multiphase (mixture) approaches at Reynolds number in the range of (3,916 - 31,331) and volume concentrations range of (0.5% ≤ φ ≤ 2%). The plain and wavy walls are subjected to a constant heat flux of 18,189 W/m2, and the flow is presumed as fully developed. The computed outcomes are validated with the correlation equations and experimental data of literature. The outcomes demonstrate that boosting the nanoadditives fraction leads to a remarkable improvement of heat transfer and hydrothermal performance indicator (HPI) of MgO-Fe3O4 /H2O Hybrid Nano-fluid through the considered tubes compared with the conventional base fluid. However, the increment is slightly higher with a wavy wall tube than with the plain one. Moreover, new correlations were suggested for specific water-based hybrid Nano-fluid volume concentrations.

The gear is a very important component of power transmission in a flying vehicle and rotating mechanisms etc... In this paper, the dynamic effect and stresses generated as a result of the mash gear will be studied by designing light-weight gears by making lightening holes of multiple diameters (14, 19, 24 and 29) mm at serval speeds (500,1000,1500,2000) that represent the variables parameter with a fixed dimension between the center of the holes and the center of rotation of the gear 43 mm and the number of 5 holes for gears with reduction ratios of gear mass ranging from (3.6%-15%) that represent the constant parameter. The 5-hole gear
is better with a hole diameter (0.1085 * Dp) which is equivalent to 19 mm in this
research with respect to the gear diameter of 175 mm. Where the maximum value
of stress concentration in the root of the tooth reached 0.655 M.N/m^2.

The flying reliability of Unmanned Aerial Vehicles (UAVs) and flying robots, which directly determines the operational degree of safety, is becoming more important in recent intelligent decades. Reliability and a high level of safety are critical for autonomously controlled flying robots, especially in transportation and entertainment applications. Subsequently, monitoring UAV health is crucial and essential for system safety, cost savings, and excellent dependability. The development of numerous monitoring strategies has resulted from the requirement for a simple and accurate unbalance classification procedure. This paper provides an Unbalance Classification and Isolation (UCI) system for multirotor UAV propeller impairments. The technique is based on the processing of signal vectors from a vibration sensor positioned in the lines of the intersection of a modern-day drone's four propulsion units, which supply data for the Fast Fourier Transform (FFT) feature extraction. To identify and locate broken blades, characteristic fault signatures collected from vibration signals are employed and displayed in real-time on the programming platform. A noticeable maximum frequency shifting percentage value of 4.2% is acquired when deviating from a healthy state. The results reveal that identifying and isolating defective rotor states has high sensitivity and outperforms current studies in regard to unbalance classification of UAVs. The adopted technique is an efficient and low-cost solution that can be implemented in any multirotor UAV.

The oxidation of aluminum machined chips makes successful recycling via the traditional re-melting technique difficult. A viable solution to this problem is to utilize solid-state recycling to transform aluminum machined chips directly into semi-finished goods, eliminating the costs of the re-melting process and minimizing CO2 emissions. In the present study, Al-6061 alloy chips have been recycled using hot extrusion followed by severe plastic deformation at ambient temperature to examine the material's mechanical properties and microstructures. The current study investigates the effects of equal channel angular pressing samples after (1, 2, and 4) cycles using a die with 90° and 20° angles, a strain of 1 was applied each pass for a maximum of four cycles at room temperature, through different routes (BC,C) on the mechanical properties of recycled specimens before and after the process. Observations showed a significant improvement in the characteristics of recycled chips exposed to hot extrusion followed by the ECAP technique. Maximum ultimate tensile strength (265, and 238 MPa) maximum yield strength (149, and 136 MPa), and elongation to failure (46 and 41%) for both routes were obtained. Moreover, each pass increases yield strength ultimate tensile strength, and micro-hardness while increasing elongation to failure. The mechanical characteristics of ECAPed specimens were higher than the extruded specimen. The mechanical properties and microstructures of solid-state recycled Al-6061 alloy chip samples were significantly influenced by the number of passes and route types.

Fatigue that occurs at elevated temperatures is called thermal fatigue. High temperatures and cycling loads cause thermal fatigue that can cause component failures. In this paper, induced the mathematical models for functionally gradient materials and three models of functionally gradient materials (FGMs) manufactured by permanent casting were tested to predict their thermal fatigue life. FGMs have been tested to determine the effect of fatigue and temperature interactions. FGMs models were of FGM1, FGM2, and FGM3 respectively, with the following volume fractions and gradations: [100%Al-50%Al50%Zn-50%Zn50%Al-100%Zn], [100%Al-30%Zn70%Al-70%Zn30%Al-100%Zn] and [100%Al-70%Zn30%Al-30%Zn70%Al-100%Zn]. The experimental procedure presented the mechanical properties as modulus of elasticity at two levels of temperatures (80℃, and 160℃). Through the results of the tensile test at high temperatures, it was noted that the reduction percentage was high in the second type. This was especially for the yield strength value, where the percentage reached 43% at 160°C. In the second type, the ultimate strength was affected more at 160°C: the decrease percentage reached 33%, and the elastic modulus at the same temperature fell by 32%. The third type is the least affected at high temperatures, as the percentage of properties decrease at 160°C reached 16, 17, and 16% for modulus of elasticity, ultimate strength, and yield strength, respectively. Fatigue strength is the most significant among the mechanical properties, where the highest value of the fatigue limit for the third type was experimentally 149.68 MPa. While the lowest value of fatigue strength was the second type, and at the same time, on the contrary, it was less affected at high temperatures, with a rate of 8%, which reached the decrease. The simulation results from the ANSYS program regarding fatigue at high temperatures were acceptable and gave reasonable variation ratios and were very close to the experimental results.

Resistance spot welding (RSW) is one of the most significant and common metal joining methods used in industries. The present paper discusses the comparative performance of resistance spot welding electrodes of nontraditional design with the traditional one of 8 mm contact diameter in welding a 1.5 mm thick low carbon steel sheet used in automobile structural bodies and bridges. The modified electrode tip surface center was machined to have three different holes of 2, 3, and 4 mm depth and three different diameters of 2, 4, and 6 mm producing nine different hollow electrode dimensions. As well as the influence of pre-heating temperature on the mechanical properties of the weld joint was investigated by considering the other main parameters of welding time, current, and force are constant. The shear tensile test and torsion test examinations are carried out to investigate the mechanical properties. Also, to interrupt the results, a macrograph examination was conducted to determine the nugget size formation. The results show that the increase or decrease in the strength of the weld joint is greatly influenced by the proper selection of the modified electrode geometries. Also, the results indicated that the maximum improvement in shear tensile strength and torsional strength is about 140% and 150% compared to the traditional one. Furthermore, pre-heating processes helped decrease the contact resistance at the faying surfaces and improve the weld tensile strength and torsional strength to about 141% and 171% at 200℃. Moreover, improvement may be achieved by slightly increasing pre-heating temperatures

In this study, natural heat convection caused by centric and vertically eccentric long horizontal cylinders under the influence of vibration is experimentally investigated. The internal wall of the annulus is heated and kept at a constant heat flux, while the outside wall is cooled and maintained at a constant temperature. The vibration frequency impacts the annular convection heat transfer process and the effects of the Rayleigh number, heat flow, and eccentricity. This work employed a moderate, laminar-ranging Rayleigh number from (5×104 to 6.48×106), while the eccentricity range is varied from (-0.667, 0, and+0.667). The investigation is carried out at five different frequencies (0, 2, 5, 10, 15, and 20 Hz); therefore, it was decided to compare the case under the same circumstances in both the absence and presence of vibration. The present results' verification worked exceptionally well in concordance with previous studies. When heat fluxes are considered, the study demonstrates that the temperature difference along the gap (radial difference) between the two cylinders significantly decreases for negative as opposed to positive eccentricities for each Rayleigh number. For different eccentricities, it was discovered that the temperature difference decreased as the Rayleigh number increased. Along with these reductions, the temperature difference was promoted as the vibration frequency increased, which is significant at (20 Hz) within the range considered for controlling parameters. It was also observed that the decrease in temperature difference is higher for the negative eccentric position than for the centric and positive positions. At vertical positive eccentricity at a low Rayleigh number, the gain in vibrational average Nusselt number caused by applying vibration had a minimum value of 22.50601475%, While at the higher value of the Rayleigh number, the maximum increase in negative vertical eccentricity was 86.66933125%. However, the gain in the average Nusselt number depends on the position of the heated inner cylinder, the Rayleigh number, and the vibrational frequency.

Thermoelectric air condition system (TEACs) powered by solar photovoltaics is useful for thermal comfort applications, especially when there is a direct energy source like sunlight. This paper presents experimental investigations of solar-powered thermoelectric air conditioning for both cooling and heating modes. The experiments were carried out in a test room whose volume is 1 m3 under the climatic conditions of the city of Baghdad. In the summer, the thermoelectric device functions as a Peltier cooler. The cold side absorbs the heat from the inside to lower the room's temperature. As for winter, the heat is released from the thermoelectric Peltier module by reversing the current applied to the thermoelectric Peltier to raise the room's temperature. In this work, the thermoelectric air condition system was supplied with different electrical power supply values with time intervals between the ON/OFF operations. The results showed that the system could heat and cool the air well in different operation conditions. The lowest temperature (22°C) is achieved in the cooling mode, with a Coefficient of Performance (COP) of 0.64 and an exergy efficiency of 0.47. In contrast, in the heating mode, the highest temperature is (31°C) with a COP of 0.87 and exergy efficiency of 0.75. This simple and eco-friendly method can minimize the cooling and heating load in the room.

Ball mills are the leading grinding equipment in the mineral processing industry. Balls are the primary component in the grinding of materials. Lifters lift these balls to the shoulder position before cataracts them to the toe position. Almost all classical theories do not consider the lifter's geometry in calculating the energy consumption of ball mills and focus only on the fill level of the charge, the lifter dimensions, their number, and the mill's rotational speed. To improve the ball mill's performance, a new shape of the lifters was proposed in the present research work. Simulation through the EDEM software and the discrete element method (DEM) was used to predict the particle behaviour and conduct a comparative study on the influence of the lifter geometry and ball mill rotational speed on torque, power draw, and kinetic energy. The validation of our results is evaluated by a confrontation of the experimental tests of discontinuous grinding with a 573 x 160 cm of Bian. The results show that using helical lifters has a more significant effect on the grinding efficiency, the torque, and the power draw of the ball mill. They decrease the wear rate of liners and lifters when mill speeds are extremely high (90%, 100%).

The importance of gas turbine engines to the aviation industry cannot be overemphasized. Being a major part of aircrafts and jets, its reliability must be second to none. They are continuously subjected to extreme conditions during service making them the subject of constant studies. To produce the thrust and torque power required of them, they have to convert the intense heat and pressure inherent in hot combustion gases. To withstand the high combustion gas temperature without thermal failure, specialized materials and cooling are employed. This study numerically investigated the effect of cooling fluid temperature on the structural integrity of a (DS) GTD111 alloy gas turbine stator blade using COMSOL 5.5 software. Air was used as the cooling fluid in this study. The duct passages of the stator blade are significantly affected by the cooling fluid temperature values. Lower values of cooling fluid temperature proved beneficial for keeping the stator blade material below its metallurgical limit and is a positive for its total displacement, it however, negatively affects the yielding of the material. The cooling fluid temperature can be optimally selected to give optimal cooling effects in terms of total displacement and stress development. Based on this study, a cooling fluid (air) temperature of about 660 K will give optimal results. Internal cooling alone is not sufficient to produce the required cooling for turbine stator blades and this is evident in the output of the study, thus, coating and film cooling must be carried out to prevent thermal failure during service.

This paper presents an analytical investigation of the nonlinear vibration characteristics of a single-phase functionally graded cylindrical shell panel with various porous metal cores. Porous constructions with varying degrees of porosity throughout their volume are known as functionally graded materials (FGMs). These materials have a wide range of applications across several industries, including shipbuilding, automotive, biomedical, marine, and aerospace. The sandwich cylindrical panel has a porous metal core, while the top and bottom faces are composed of homogeneous materials. The model is improved using a power-law function. The governing equations of motion are discretized according to the classical thin shell theory with von Karman nonlinear strain-displacement relations by applying Galerkin's method to a collection of ordinary nonlinear equations. The nonlinear equations are determined using the fourth-order Runge-Kutta method, which is implemented in MATLAB software. The influences of core materials, porosity distribution, FG core thickness, face sheet layers, and changing gradient index on the natural frequency and dynamic response of the FG cylindrical shell are discussed. The existing literature is used to compare the current findings, and a favorable level of consistency is observed. The results obtained indicate that the porosity coefficients have a notable impact on the vibration behavior and overall reliability of functionally graded structures. The results demonstrate that when the porous parameter is increased, the natural frequencies of the FG sandwich cylindrical also increase. Nevertheless, this paper also presents several new and valuable results that may be of great reference to the readers.

Induction motors and steam turbines are the main components in the sugar cane milling process. This study analyzes the efficiency of induction motors and steam turbines as mill drives at the Kebon Agung Sugar Factory in Malang, Indonesia. This study used experimental methods by observing and testing at the Kebon Agung Sugar Factory. The induction motors analyzed were mills 1, 2, and 5. Meanwhile, the steam turbines analyzed were cane cutter 1, 2, heavy-duty hammer shredder, mill 3, and mill 4. Motor and turbine data were obtained through the control system. Furthermore, the motor and turbine data are processed, and the efficiency comparison is calculated. From the results of the analysis, the average value of the efficiency of an induction motor is more significant when compared to a steam turbine. The average weight of induction motor efficiency is 94.6%, and the average value of steam turbine efficiency is 77.2%. This research recommends that the Kebon Agung Sugar Factory replace the steam turbine with an induction motor in the future. The recommendation given to Kebon Agung Sugar Factory is the use of induction motors on CC 1, CC 2, HDHS, mill 1, and mill 5. An induction motor is a relatively easy install compared to a steam turbine; the construction is robust and highly efficient, requires minimal maintenance, and does not require special equipment during operation.