This four-hour short course provides an introduction to fluids for aerospace hydraulic systems. Topics covered include an introduction to basics fluid properties, rheology, tribology, and fluid product development. In addition, the history and performance of different classes of fluids are discussed in detail, and specific failure modes such as erosion and sludge formation will be described. Along with an introduction to fluid degradation, information on used oil analysis test methods and interpretation will be provided.
This paper discusses a study conducted to better understand the factors that influence human comfort. Numbers of other studies have been done which focus on seat comfort. Our studies focused on the impact of foam density and foam hardness on seat comfort. Human seating comforts are associated with many parameters but for our studies, we have considered density and hardness. Physical PU foam models were developed for analyzing the seat comfort. Based on the model, the effect of density and hardness has been predicted. This study included various PU foam density and hardness and their effect on seat comfort. This study will help us to understand, how these two parameters influence the seating comfort. Pressure mapping was used to investigate, how changing in foam density and hardness affect the seat comfort. The effect of PU foam density and hardness are very large on seat comfort. Therefore the density and hardness should be carefully selected.
This paper presents the free surface behaviour of liquid while degas tank bottle is in service. The liquid in the degas tank is subjected to exceed the mean line in the service and the fluid levels in all chambers varies as there is continuous movement and sloshing in the fluid. The objective of this work is to optimise the baffle design such that the fluid level in the tank does not exceed the mean line in service and fluid in the all chambers need to be maintained at same level. The scope of work is also to enhance the tank baffles which will dampen the fluid sloshing and the fluid de-aeration should be done effectively to avoid any possible structural damage. The simulation of liquid free surface behaviour under uniform acceleration is done using STAR CCM+ software. A numerical model is developed based on Volume of Fluid (VOF) technique to track the free surface motion of liquid. The explicit time discretization scheme is employed to solve the volume fraction equation.
The purification efficiency of exhaust gas catalysts depends on several factors. One of the most important factors is the diffusivity of the exhaust gases in the catalytic coating layer, especially at moderate to high temperature and space velocity conditions. Porous silica, γ-alumina, zirconia, carbons and many other porous crystalline materials that are commonly used as catalysts and catalyst supports are traversed by a labyrinth of tortuous micro and mesopores. If the connectivity is very low, the labyrinth of pores becomes more difficult to penetrate, increasing the overall “tortuosity” and slowing down the transportation of gas molecules within catalyst layers. A new approach to overcome these diffusion and transport limitations in an exhaust gas catalyst is to create an interconnected network of mesopores and macropores via increase in void fractions within the washcoat components and layers.
Valve seat inserts (VSI) are installed in cylinder heads to provide a seating surface for poppet valves. Insert material is more heat and wear resistant than the base cylinder head material and hence it makes them better suited for valve seating and improved engine durability. Also using inserts permits easier repair or rebuild of cylinder heads as only the wear surfaces need to be replaced. Desirable performance characteristics are appropriate sealing, heat-transfer and minimizing valve to VSI wear and undesired outputs include valve seat dropping and cracking. With downsizing trend of diesel engines, it leads to increasing power density and therefore higher cylinder pressure and temperatures. Hence the engine components are getting exposed to more severe loadings and hence to failure modes, which were not heretofore experienced based on the warranty data.
Bogie-type suspensions for trucks are comprised of two axles and a central spring pack on each side of the truck chassis. Bogie suspensions have a good load distribution between the axles and are used for severe applications in trucks, in off-road conditions thereby subjecting them to extreme stain and load. In today’s competitive market scenario, it of utmost importance to minimize down time in commercial vehicles as it directly corresponds to loss in business which leads to customer dissatisfaction. It is therefore essential to optimize and select the right material for each component in the bogie suspension system. This paper deals with the material selection and testing of one such component - Bogie Wear Pad. The bogie wear pad undergoes sliding friction throughout its lifetime during loading and unloading of bogie suspension. Three different materials are selected and their wear is measured under the same conditions of loading.
Engine performance and emission control are key attributes in the overall engine development and sealing of the mating components plays an important role to achieve the same. Rubber gaskets are being used for sealing of different Internal Combustion (IC) engine components. Gasket sealing performance needs to be ensured at initial development stage to avoid the design changes at the later part of development cycle. Design changes at later stage of development can potentially influence parameters like optimization avenues, cost and time to market. Demand of utilization of virtual tools (front loading) is growing with the increasing challenges like stringent product development cycle time and overall project cost. This paper describes a procedure to simulate the rubber gasket and groove for different material conditions (dimensional tolerances). This entire simulation is divided into two phases. In the first phase of the simulation, Load Deflection curve (LD curve) is established.