<div class="section abstract"><div class="htmlview paragraph">Modern water injection systems typically deliver water separately from the primary fuel system using a discrete injector either through the intake port or directly to the cylinder. Recently, however, water dilution strategies using fully hydrous fuel systems have been receiving increased attention. Hydrous fuels are water and liquid fuel blends that are fully mixed prior to delivery to the combustion system. Removing water from naturally hydrous fuels such as ethanol requires large amounts of energy; consequently, it is possible to combine water injection with more economical production by leaving some amount of water in the fuel. This paper compares experimentally the water dilution effects on the combustion and emissions characteristics and overall engine performance when delivering the water through either a hydrous fuel blend or discrete port water injection.</div><div class="htmlview paragraph">A 2.4L 4-cylinder NA GDI engine was used in experimental testing. The engine was controlled using an aftermarket ECU interfaced with OEM components and a laboratory-grade wide-band oxygen sensor for equivalence ratio quantification and feedback. The results indicated that for brake measurements the type of water addition affects combustion sufficiently enough to be measured and quantified. ISFC reduction ranged between 0.5 and 2% for water injection and 0.5 and 3% for hydrous fuel. Combustion stability tended to be not strongly affected or degraded by water addition. Combustion analysis demonstrated retarded combustion timings and reduced peak pressures of up to 8.5% for all water dilution cases with the largest reductions at the highest speed and load points. Emissions effects showed mixed results that depended on both speed and type of water addition.</div></div>
Rock climbing falls can be safely stopped and are often a routine part of the sport. However, safety may be compromised not only by equipment failure but also due to the climbers’ misjudgment of the situation. Current literature and other resources are either based on laboratory experiments or lacking specific and systematic measurements of the relevant parameters of lead climber falls. Only one recent theoretical paper describes the physics of lead climber falls under realistic conditions. To provide research-based safety guidance for the climber community systematic studies of various scenarios are needed. In this study experimental data were collected and analyzed from lead climber falls on an actual climbing route, recording all positions prior to and after the fall as well as climber and belayer acceleration data. The data reveal the actual fall height, the forces acting on belayer and climber and the dissipation mechanisms of the fall energy. Two test series were performed, varying the fall height or the belayer mass, respectively. Substantially longer total fall heights are found, in particular for lighter belayers, even for relatively short falls. The major mechanisms to dissipate the energy are the energy losses when accelerating the belayer of the ground and the friction force in the loaded carabiner. The study concludes with recommendations for best practice under various conditions for a safe climbing experience.
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