Jamaluddin Md. Sheriff

Bio-based lubricants for numerical solution of elastohydrodynamic lubrication

This paper presents a programming code to provide numerical solution of elastohydrodynamic lubrication problem in line contacts which is modeled through an infinite cylinder on a plane to represent the application of roller bearing. In this simulation, vegetable oils will be used as bio-based lubricants. Temperature is assumed to be constant at 40°C. The results show that the EHL pressure for all vegetable oils was increasing from inlet flow until the center, then decrease a bit and rise to the peak pressure. The shapes of EHL film thickness for all tested vegetable oils are almost flat at contact region.

Numerical Solution of Hydrodynamics Lubrications with Non‐Newtonian Fluid Flow

This paper focuses on solution of numerical model for fluid film lubrication problem related to hydrodynamics with non‐Newtonian fluid. A programming code is developed to investigate the effect of bearing design parameter such as pressure. A physical problem is modeled by a contact point of sphere on a disc with certain assumption. A finite difference method with staggered grid is used to improve the accuracy. The results show that the fluid characteristics as defined by power law fluid have led to a difference in the fluid pressure profile. Therefore a lubricant with special viscosity can reduced the pressure near the contact area of bearing.

Effect of Nozzle Angleson Spray Losses Reduction

Spray losses are the most important problem that is faced in the spray application process as result of spray drift to non target areas by the action of air flow.This paper investigated the spray drift for banding applicationusing even flat-fan nozzle TPEunder wind tunnel conditions.In addition, this paper also examined the effect of different spray fan angles 65°, 80° and 95° on spray drift particularly where there is need to make the nozzle operate at the optimum heights above the ground or plant level.In addition, three cross wind speeds 1, 2 and 3m/swere produced to determine the effect of wind speed on total spray drift.According to the results from this study, the nozzle anglehas a significant effect on the total spray drift. The nozzle angle 65° gave the highest drift reduction compared to the other nozzle angles. The maximum driftfor all nozzles was found at nozzle height of 60 cm. The minimum mean value of the drift was found at wind speed of 1 m/s. This study supports the use of nozzle angles of less than 95° on heights more than 0.5m and on wind speeds more than 1m/s as a means for minimizing spray drift.

Numerical Analysis of Elastohydrodynamic Lubrication with Non-Newtonian Lubricant

Elastohydrodynamic lubrication is a form of hydrodynamic lubrication involving physical interaction between two contacting surfaces and liquid where elastic deformation of the contacting surfaces due to heavily loading applied will affect the elastohydrodynamic pressure and fluid film thickness significantly. In this paper, a line contact EHL is modeled through the cylinder contact to a flat surface to represent the application of roller bearing. This solution is limited to two dimensional line contact problem only, an infinite length of cylinder was used as physical modeling. The behavior of non-Newtonian fluid also was investigated using power law fluid model. Bearing speed is to be assumed in steady state and temperature is assumed constant. The bearing performance parameters such as pressure and film thickness of lubricated contacts are calculated using Newton-Raphson method.The results show that the peak pressure increases as the parameters such as velocity, load and material parameter were increases and the spike was found to shift to the center of roller. The film was almost flat at contact region and formed a dimple shape near the outlet flow. The value of pressure spike and minimum film thickness were smaller at lower speed and were increased during raising speed then the peak point was found to be shifted to center of roller.

Effect of nozzle type on spray drift in banding application

The most important problem that faces spraying application process in the field is spray losses as result to spray drift to non target areas by action of air flow. Spray drift from conventional TeeJet even flat nozzle TPE and Drift Guard Even flat nozzle DGE (pre orifice nozzle) for banding application was investigated and compared under wind tunnel conditions. This paper examined effect nozzle heights 50 and 60 cm on spray drift. To determine the effect of wind speed on spray drift, wind tunnel was used to product three cross wind speeds 1, 2 and 3m/s. According to the results from this study, nozzle type affected significantly the spray drift. Increasing wind speeds had a high significant effect on increasing the spray drift. Nozzle height affected significantly the spray drift, the closer the nozzle is to the ground, the more the likelihood of spray drift is minimized. This study supports the use of nozzle type DGE as a means for minimizing spray drift.

The Effect of Wavy Groove Liner on Pressure Distribution of Journal Bearing

The ability of bearing liner to maintain the fluid film lubrication is crucial to its performance. This study is to investigate the pressure distribution for full film lubrication of wavy bearing liner. The results were compared to that from smooth bearing liner. These bearings were used with the palm oil based lubricant. CFD analysis was developed to determine the numerical data. A 60 mm bearing with ratio 0.5 of its diameter to length is simulated. This bearing has 250 µm in clearance and 200 µm in amplitude with semi rectangular circumferential surface waviness liner in shape. Pressure distribution of the bearing was influenced by the increment of the eccentricity ratio and the speed of shaft. The surface waviness liner bearing produces higher in pressure by comparing it with the smooth bearing. The maximum pressure was noted in the vicinity of minimum fluid film thickness where it was distributed at the area around the peak of wave.

Effect of semi-circular wavy liner on performance of journal bearing

The amount of lubricant present in a bearing can affect its performance. This study compares the load carrying capacity of wavy and smooth surfaces liner bearing so that the potential advantages of the former could be identified. Both types of bearing used palm oil as lubricant and computational analysis was developed to predict the numerical data for full film lubrication condition. The bearing model was 60 mm in diameter and its ratio of length to diameter was 0.5 with clearance and amplitude of 250μm and 200μm respectively. All cases studied included temperature effect under steady flow conditions with speed between 200 and 5000 rpm. The results show, for low eccentricity ratio, semi circular wavy liner bearings were able to produce higher load carrying capacity. The results also show that the overall temperature drop for wavy liner surfaces was higher for all test conditions. The shaft speeds, however, have no direct effect on the magnitude of the load carrying capacity.

Effect of circumferential groove sinusoidal waviness on the load carrying capacity of journal bearing with bio-based lubricant

Present study compared the load carrying capacity of grooves surface waviness and a linear are determined with bio-based lubricant to identify the potential advantages of the journal bearings. CFD analysis was developed to predict the numerical data under full film lubrication. 60mm in diameter of bearing with the ratio length to the diameter is 0.5, a clearance 750 µm, and 600 µm of wave amplitude were performed. Sinusoidal wavy surface produced better results in term of load capacity than the linear journal bearing. Generally, the load carrying capacity is influenced by the increasing in shaft speed and the eccentricity ratio.

Pressure analysis in point contact for elastohydrodynamic lubrication

The issue of failure in elastohydrodynamic has been investigated by many researches. In this study, numerical approached is used to determine the deformation of the disc and its effect to the pressure distribution. Two numerical software were used is sequential manner. The shear stress on the disc was also found to shift closer to the inlet as the disc deforms, where pressure was observed to be fluctuating in the contact area.

Numerical Analysis of Flow and Heat in Variable Angle Slider Bearing

In this study, two‐dimensional numerical approach is used to analyse flow and heat transfer in the gas slider air bearing. The flow field of a micro scale channel between an inclined slider and a moving bottom wall is calculated under a variety of slider postures. The heat transfer through the channel is also calculated with variety bottom wall speed. The effects of the variable inclined angles of the slider and the variable bottom plate velocities of the channel on pressure distributions profiles are presented. The relationships of the peak pressure and windward angle, and the positions of the peak pressure along the channel are also obtained. The effects of variation in pitching angle of slider bearing on a two‐dimensional heat analysis are further investigated. In this analysis, the highest pressure is obtained when the inclined angle is between medium to high cases. The location of peak pressure found to be located at 0.95 of Xc/L. The highest temperature is obtained when the inclined angle is at low....