Computer Simulation for Haulage Performance of Power Tiller
The presence of a large number of marginal and small land holdings in India has rendered the power tiller to be the most suitable farm equipment for field operations, in view of its compact size, profitability and versatility, but the transport work which is also required to carry the farm produce is yet to be proved. Keeping these in mind, user friendly software was developed for predicting the haulage performance of power tiller to meet requirements in educational and research organizations. The developed software requires input parameters such as power tiller, trolley and operating conditions. The developed software was validated by conducting experiments with a 6.7 kW power tiller using a suitable trolley on tarmacadam road at various payloads and road slopes. The draft, slip, fuel consumption and speed were measured and other haulage performance parameters were calculated based on measured values to validate the developed software. The results simulated by software indicate lower draft and slip in the range of 1-23 and 2-9% with respect to the experimental data, however, higher transport productivity was in the range of 3-12%.
Importance of automatic variable single hitch point for 2WD tractors – A theoretical analysis
Abstract Software is developed in Visual Basic 6 environment for predicting the haulage performance of 2WD tractor. Three types of inputs namely tractor, trailer and operating parameters are required to run the software. Various empirical and theoretical equations were used for predicting the haulage performance parameters such as draft, slip, actual speed, transport productivity, transport efficiency, fuel economy index, front and rear wheel utilization factor etc. In addition to this, the software also gives a warning signal when either stability of tractor or engine power fails. It was used to evaluate the haulage performance by varying the hitch height (HH) at various operating conditions. It was observed that there is a significant increase in the maximum payload 78, 300 and 3300% while HH was lowered from 0.7 to 0.1 m at 0, 5 and 10° slope, respectively. However, the dynamic load on rear axle increased from 1470 to 1730 and 1500 to 1820 kg when HH increased from 0.1 to 0.7 m at 800 and 1000 kg payload, respectively. Further, it was observed that fuel economy index was reduced by 6.3% and engine power requirement by 4.23% at 800 kg payload when HH was raised from 0.1 to 0.7 m. It was observed that stability of tractor increases by lowering the HH, however, traction increases by raising the same. Hence, it was concluded that variable HH can meet the requirements of stability as well as traction during transport as per necessity.
Computational fluid dynamics as a development tool for rotary blood pumps.
Computational fluid dynamics (CFD) is beginning to significantly impact the development of biomedical devices, in particular rotary cardiac assist devices. The University of Pittsburgh's McGowan Center for Artificial Organ Development has extensively used CFD as the primary tool to analyze and design a novel axial flow blood pump having a magnetically suspended rotor. The blood-contacting surfaces of the pump were developed using a design strategy based on CFD that involved closely coupling a Navier-Stokes solver to a parameterized geometry modeler and advanced mesh movement techniques. CFD-based blood damage models for shear-induced hemolysis as well as surrogate functions describing thrombosis potential were employed to help guide design improvements. This CFD-based design approach resulted in the timely development of a pump subjected to multiple geometric refinements without building expensive physical prototypes for each design iteration. A physical prototype of the final improved pump was fabricated and experimentally analyzed using particle imaging flow visualization. The CFD predicted results correlated well with the experimental data including pressure-flow (H-Q) performance and specific flow field features. It is estimated that the present CFD-based design approach shortened the overall design time frame from an order of years to months.