Virtual Indication of the Torque for a Marine Gas Turbine

Gas turbines are used in marine applications where high propulsion power is required compared to engine size and mass. In some cases, the torque and engine power developed cannot be measured with a special transducer implemented in applications or if there are indications, they need to be compared with the calculated torque indication. For this purpose, we developed in the engine control software application a mathematical model for calculating and displaying the torque and power developed by the engine. Through comparisons in the tests with the engine on the test bench, this mathematical model was refined. At this time the comparative sampled data can be used as a virtual indication of torque in cases where this is necessary.

Analysis of Air Pollutant Emission Inventory from Farm Tractor Operations in Korea

Due to the decline in the agricultural labor force and rapid aging of farmers, agricultural machinery is becoming larger, higher-performance, and diversified. In this study, an air pollutant emission inventory for agricultural tractors was analyzed and compared with the inventory developed by a national agency. Agricultural tractors include walking and riding tractors and, further, riding tractors were divided into three subcategories based on their engine size. In addition, tractor emissions were classified according to the usage time of each operation. Seven air pollutants, such as CO, NOx, SOx, TSP, VOCs (PM10), PM2.5, and NH3, were included in the inventory. The results showed that the total yearly emissions in 2017 were 3300 Mg, 9110 Mg, 4 Mg, 567 Mg, 522 Mg, 759 Mg, and 33 Mg for CO, NOx, SOx, TSP, VOCs, PM10, PM2.5, and NH3, respectively. The most emitted air pollutant in the transporting operation using walking tractors is NOx, and the amount of emission is 1023 Mg/y. Riding tractors mainly emit a large amount of NOx, in the order of medium, large, and small tractors. The NOx emissions from medium, large, and small riding tractors are 1103 Mg/y, 676 Mg/y, and 322 Mg/y, respectively, from harrowing operations and are 445 Mg/y, 273 Mg/y, and 130 Mg/y, respectively, from tilling operations. The results also showed that the total pollutant emissions from tractors were increased 10% compared to the emission inventory developed by a national agency due to categorizing riding tractors into three subcategories. A geographic information system (GIS) was used to spatially assign air pollutant variables to 17 provinces and metropolitan cities in Korea.

A Fundamental Thermodynamic Investigation of Compression Ratio Effects in Relation to Diesel Engine Size

In this study, a fundamental generalized thermodynamic model of internal combustion engines was applied to evaluate engine compression ratio effects principally in relation to engine size. Performance and efficiency metrics were investigated systematically. Further, cylinder wall temperature was varied across a range of cold start to stabilized operating temperatures. A very broad range of engine bore sizes and bore-to-stroke ratios were evaluated, representing small to large diesel engines in service. In general, it was observed that engine efficiency increases moderately with increasing compression ratio and bore size. Additionally, surface area-to-volume ratio is a critical metric when evaluating various size engines. This leads to greater relative heat transfer in the smaller bore engines with higher compression ratios. The sensitivity to heat losses is also much greater in the smaller engines. Smaller engines with higher compression ratios are expected to be most affected by cold starting conditions. Exhaust enthalpy is highest for larger bore engines with lower compression ratios, an important consideration for engine boosting. Higher convective heat transfer coefficients are also expected in smaller bore engines with higher compression ratios due to the higher operating pressures.

A General Framework for Crankshaft Balancing and Counterweight Design

In the automotive field, the requirements in terms of carbon emissions and improved efficiency are shifting the focus of designers towards reduced engine size. As a result, the dynamic balancing of an engine with strict limitations on the number of cylinders, the weight and the available space becomes a challenging task. The present contribution aims at providing the designer with a tool capable of selecting fundamental parameters needed to correctly balance an internal combustion engine, including the masses and geometry of the elements to be added directly onto the crankshaft and onto the balancing shafts. The relevant elements that distinguish the tool from others already proposed are two. The first is the comprehensive matrix formulation which makes the tool fit for a wide variety of engine configurations. The second is an optimisation procedure that selects not only the position of the mass and centre of gravity of the counterweight but also its complete geometric configuration, thus instantaneously identifying the overall dimensions and weight of the crankshaft.

Effect of radial inflow distortion on the performance of a highly loaded tandem stage

Engine size and weight optimization have always been high-priority design objectives for designers. Compressors occupy a relatively large part of the gas turbine engine. Owing to the adverse pressure gradient in the compressor, achieving the required pressure ratio within fewer stages has been a challenging task for compressor designers. Tandem blading is one of the novel concepts, which could be used to increase the pressure ratio by means of higher flow turning through the blade passages. This paper presents the performance characteristics of a tandem stage based on results from experiments and numerical analyses. The investigation is further extended to analyze the effect of a radial hub and tip distortion on the performance of the tandem stage. The experimental results are very well supported with some interesting numerical results, particularly near the hub and tip region. It is observed that the tandem stage demonstrates higher pressure rise and stall margin under clean inflow. The tandem stage is also observed to be more sensitive to radial distortion leading to a significant loss in the total pressure and the stall margin.

Hybrid Electric Vehicles: A mini Overview

The present greenhouse effect and its arrays of limitations on energy sources have made Hybrid Electric Vehicles (HEV’s) a current research focus due to its reduced amount of fuel usage. The ability to simultaneously deliver power to the wheels from the mo-tor/engine made HEVs to have greater advantages (less fuel consumption and reduced internal combustion engine size without compromising the power output) over the tradi-tional vehicles. Despite its low patronage in markets, there is still hope that its popularity in the market will rise due to the superior qualities associated with it. This paper presented an brief review of Hybrid Electric Vehicles, by focusing on history, architecture and energy sources.

Evaluation of soil EC mapping driven by manual and autopilot-automated steering systems of tractor on oil palm plantation terrain

The autopilot-automated steering system is one of today’s modern technologies in a tractor’s driving system for conducting the operations in farmland. However, further study on the suitability of this steering technology on a particular geographic region is still a necessity. This study evaluated the precision of tractor operations with soil sensor implement using manual and autopilot-automated steering systems on oil palm plantation terrain in Malaysia. A New Holland TD5.75 tractor with 75 hp engine size equipped with a Trimble autopilot-automated steering system pulling a Veris 3100 soil electrical conductivity (EC) sensor was tested in this study. The findings showed that each steering system generated a little different pattern of spatial variability in interpolated soil EC maps. Apart from that, autopilot-automated steering system offered better performances by saving energy expenditure of operator and improving the field capacity of operation. Conclusively, tractor with autopilot-automated steering presented a great suitability for the use in agricultural operations in Malaysia.

Perancangan Mesin Pencacah Plastik Tipe Shredder dan Alat Pemotong Tipe Reel

<p><em>Plastic is an object that can support human daily activities due to its character that is practical and resistant. However, wasted plastic can pollute the environment since it is difficult to be decomposed. The purpose of this study was to produce plastic chopper machine that is capable of chopping plastic waste with shredder type and reel type cutting tools. The design process is chosen based on a predetermined assessment. The kinds of plastic that are chopped will be PET (polyethylene terephthalate) and HDPE (high density polyethylene) plastic. AISI 304 material knife was chosen to chop up plastic waste. According to the results of design and calculation, the engine size has dimensions of 1105.6x1355.7x600, 3 HP motor drive power, and has a rotation of 1450 rpm which is assisted by pulley transmission elements and v-belt type A. The chopper components used consist of 14 pieces of shredder blade and 9 blade reel cutters with 2 pieces of bedknife. The components of shredder knives, reel knives, and frames are analyzed using Finite Element Analysis to determine the safety of the planned design.</em></p>

A Large-Eddy Simulation Study of Contrail Ice Number Formation

Ice crystal number is a critical ingredient in the potential climate impact of persistent contrails and contrail-induced cirrus. We perform an extensive set of large-eddy simulations (LES) of ice nucleation and growth within aircraft exhaust jets with an emphasis on assessing the importance of detailed plume mixing on the effective ice-number emission index (EIiceno) produced for different conditions. Parameter variations considered include ambient temperature, pressure, and humidity; initial aerosol origin (exhaust or ambient), number, and properties; and aircraft engine size. The LES are performed in a temporal representation with binned microphysics including the basics of activation of underlying aerosol, droplet growth, and freezing. We find that a box-model approach reproduces EIiceno from LES well for sufficiently low aerosol numbers or when crystal production is predominantly on ambient aerosol. For larger exhaust aerosol number the box model generally overestimates EIiceno and can underestimate the fraction from ultrafine aerosol. The effects of different parameters on EIiceno can largely be understood with simpler analytic models that are formulated in low and high aerosol-number limits. The simulations highlight the potential importance of “cold” contrails, ambient ultrafine aerosols, crystal loss due to competition between different-sized crystals, and limitations on reducing EIiceno. We find EIiceno insensitive to engine size for lower aerosol numbers, but decreasing with increasing engine size for higher aerosol numbers. Temporal versus spatial representations for jet LES are compared in an appendix.

Framework for estimation of nacelle drag on isolated aero-engines with separate jets

Typically, the evaluation of nacelle drag in preliminary design is required to find an overall optimum engine cycle and flight trajectory. This work focuses on the drag characteristics of aero-engine nacelles with separate jet exhausts. The main body of analysis comes from 3D numerical simulations. A new near-field method to compute the post-exit force of a nacelle is presented and evaluated. The effects of the engine size, Mach number, mass flow capture ratio and angle of attack are assessed. The results obtained from the numerical assessments were used to evaluate conventional reduced-order models for the estimation of nacelle drag. Within this context, the effect of the engine size is typically estimated by the scaling ratio between the maximum areas and Reynolds numbers. The effect of the angle of attack on nacelle drag is mostly a function of the nacelle geometry and angle of attack. In general, typical low-order models based on skin friction and form factor can underestimate the friction drag by up to 15% at cruise operating point. Similarly, reduced-order models based solely on Reynolds number, and Mach number can underestimate the overall nacelle drag by up to 74% for free stream Mach number larger than the drag rise Mach number.