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Welding is one of the most convenient and extensively used manufacturing process across every industry and is recognized as a cost effective joining technique. The root cause of most of the fabricated structural failures lies in the uncertainties associated with the welding process. It is prone to generate high residual stresses due to non-volumetric changes during heating and cooling cycle. These residual stresses have a significant impact on fatigue life of component leading to poor quality joints. To alleviate these effects, designers and process engineers rely upon their experience and thumb rules but has its own limitations. This approach often leads to conservative designs and pre-mature failures. Recent advances in computational simulation techniques provide us opportunity to explore the complex phenomenon and generate deep insights. The paper demonstrates the methodology to evaluate the residual stresses due to welding in virtual environment.

In this present investigation an attempt has been made to simulate the refrigerant flow through pipes using Computational Fluid Dynamics (CFD) to observe liquid refrigerant R134a flashing phenomenon using multi-phase model in ANSYS Fluent. In a vehicle HVAC piping system the refrigerant flows under a certain operating condition and pipe packaging. When the vehicle is kept in idle condition there is a possibility that a local pressure drop may occur due to change in pipe configuration or change in operating conditions. This leads to phase change and it can be one of the factor which causes noise and vibrations in the refrigerant pipe. The unwanted noise created due to refrigerant fluid phase change inside HVAC pipe can be annoying to end user. Prediction of refrigerant flow noise through HVAC pipes is more challenging and a time consuming process.

An automotive radiator cooling fan has been observed to be an important noise source in a vehicle and with increasing noise refinements, the need for a quieter but effective fan is of utmost importance. Although some empirical prediction techniques are present in literature, they are not sufficiently accurate and cannot give a detailed view of the entire noise spectrum and the various noise prone zones. Hence the need for highly accurate Computational Fluid Dynamics (CFD) study is essential to be able to resolve the minute acoustic stress. Large Eddy Simulation technique in CFD is used to resolve the minute scales of motion in the flow as the sound pressures simulated are very small compared to system level pressures and require immense accuracy. Detailed mesh dependency and Y+ studies are conducted to implement higher accuracy as well as keep mesh requirements within computationally feasible zone.