Modeling of fluid dynamics interacting with ductile fraction propagation in high pressure pipeline

This paper presents a computational model for the fluid dynamics in a fractured ductile pipe under high pressure. The pressure profile in front of the crack tip, which is the driving source of crack propagation, is computed using a nonlinear wave equation. The solution is coupled with a one dimensional choked flow analysis behind the crack. The simulation utilizes a high order optimized prefactored compact-finite volume method in space, and low dispersion and dissipation Runge-Kutta in time. As the pipe fractures the rapid depressurization take place inside the pipe and the propagation of the crack-induced waves strongly influences the outflow dynamics. Consistent with the experimental observation, the model predicts the expansion wave inside the pipe, and the reflection and outflow of the wave. The model also helps characterize the propagation of the crack dynamics and fluid flows around the tip of the crack.

Fat Reduction and Replacement by Olive Oil in Bologna Type Cooked Sausage. Quality and Nutritional Aspects

Eight different types of Bologna type cooked sausages apart from the control were produced in order to reduce the fat content (15%, 30%, 45%), replace the animal fat by olive oil (3%, 6.5% and 10%) as well as concomitant reduction and replacement of animal fat (30% of fat reduction with 2% of olive oil as an animal fat replacer). Quality attributes such as texture, water binding and color were monitored. Texture and water binding of fat reduced and fat replaced samples were quite similar to the control while color was strongly affected by the fat reduction and replacement. Fat reduction led to a redder cooked sausage and the addition of olive oil to a more yellow product. Chemical analysis revealed no major changes among samples apart from protein and fat content and fatty acid profile. Noteworthy, cooked sausage with more than 6.5% of olive oil achieved the World Health Organization’s recommendation on the nutritional fat index ((polyunsaturated + monounsaturated)/saturated fatty acid ≥ 2) which is very relevant to the development of healthier formulations. Cooked sausages with 45% of fat reduction and 30% fat reduced with 2% of olive oil were considered as the best by the panelists, which in addition had a balanced nutritional content by a lower caloric content. We concluded that fat reduction (up to 45%) and replacement (up to 10%) are possible with acceptable sensory quality and improved nutritional composition. When replacing animal fats by plant oils, the color of the product, which has a strong influence on the sensory acceptability of Bologna type cooked sausages, is affected. Therefore it must be controlled for a proper product development of meat products containing vegetable oils.

Energy saving design of the machining unit of hobbing machine tool with integrated optimization

The machining unit of hobbing machine tool accounts for a large portion of the energy consumption during the operating phase.The optimization design is a practical means of energy saving and can reduce energy consumption essentially.However,this issue has rarely been discussed in depth in previous research.A comprehensive function of energy consumption of the machining unit is built to address this problem.Surrogate models are established by using effective fitting methods.An integrated optimization model for reducing tool displacement and energy consumption is developed on the basis of the energy consumption function and surrogate models,and the parameters of the motor and structure are considered simultaneously.Results show that the energy consumption and tool displacement of the machining unit are reduced,indicating that energy saving is achieved and the machining accuracy is guaranteed.The influence of optimization variables on the objectives is analyzed to inform the design.

Flow-Induced Acoustics in Corrugated Pipes

When gas flows through corrugated pipes,pressure waves interacting with vortex shedding can produce distinct tonal noise and structural vibration.Based on established observations,a model is proposed which couples an acoustic pipe and selfexcited oscillations with vortex shedding over the corrugation cavities.In the model,the acoustic response of the corrugated pipe is simulated by connecting the lossless medium moving with a constant velocity with a source based on a discrete distribution of van der Pol oscillators arranged along the pipe.Our time accurate solutions exhibit dynamic behavior consistent with that experimentally observed,including the lock-in frequency of vortex shedding,standing waves and the onset fluid velocity capable of generating the lock-in.