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In this investigation, Computational Fluid Dynamics (CFD) is used to numerically simulate vehicle defroster performance. The general-purpose CFD package FLUENT/UNS is used to perform the numerical simulation. It is difficult to accurately model the actual flow and conjugate heat transfer phenomena in the vicinity of the windshield because of the complexity of the geometry and flow conditions, including the correct turbulence model. The objectives of this study are to quantify the velocity field in the vicinity of the windshield due to defroster jet flow, predict the windshield defrost pattern, and validate the use of CFD simulation in the engineering design and development process. This paper identifies the computational methodology and presents the simulation results. It also contains the hot-wire validation measurements for the velocity field as well as the cold room testing of the defroster performance.

Computational Fluid Dynamics (CFD) is used in this investigation to determine the velocity field in the vicinity of vehicle windshield due to defroster flow. The analysis was performed using the CFD package STAR-CD. CFD results were obtained and compared to test data. Hot-wire anemometry was used to experimentally determine the velocity field in the vicinity of the defroster nozzle jet flow and windshield interior surface. The experimental results were used to verify the integrity of the CFD models and validate our use of CFD modeling. The ability of the CFD models to quantify the flow field can be inferred from the present results. Based on the degree of correlation of the velocity profiles between the CFD simulations and the experimental work, it can be concluded that CFD simulation is a valid technique to investigate the air flow characteristics of vehicle defroster and windshield flow field.

Rapid and effective windshield defrosting has been the goal of various investigations by automotive engineers around the world. Car manufacturers have invested considerable resources to satisfy the thermal needs, safety requirements, and comfort demands of their customers. This paper addresses the climate control issues of defrosting automotive windshields. The paper summarizes the state of knowledge of the various approaches for improving defroster performance. Experimental as well as computational efforts, accompanied by heating techniques and heat boosters will be presented. The paper also features relevant measurement methods for airflow and thermal patterns, and discusses current challenges. Recommendations are made on where to focus engineering and design efforts given the state of present technologies.

Hot-wire anemometry is used to experimentally determine the velocity field in the vicinity of the defroster nozzle jet flow and windshield interior surface. It provides quantitative velocity measurements necessary to determine the heat transfer coefficient on the windshield. Measurements are useful when used as a design tool to predict defroster and windshield flow. A modified traverse device was constructed to carry the hot-wire probes. The results obtained from the modified technique are more accurate and provides a valuable insight into the boundary-layer structure over the windshield.

This paper describes the results of a design of experiment DOE applied to an automotive HVAC blower system. The DOE evaluates the influence of a selected three design parameters of a blower housing scroll on the performance of the blower system, and the interaction between these parameters. The effects of the blower scroll starting angle, defined by a selected clearance between the outer diameter of the blower fan and the nearest point on the scroll cut-off edge, the clearance between the top of the blower fan and its housing scroll, and the type of scroll expansion are concluded. A Three Dimensional computation CFD is used to select the DOE levels of each parameter, based on the inspection of the CFD air flow field, and the produced static pressure field. The DOE results are illustrated by the main effects plots, interaction plots, and the ordered effects of the regression analysis.

Application of Atmospheric Pressure Chemical Vapor Deposition (APCVD) to the production of thin film coated glass is addressed in this study. Several layers of thin solid film are deposited on the surface of the glass as it moves underneath the APCVD applicator system at high temperature. High velocity in the vicinity of the deposition zone is desirable. Two separated regions of recirculating fluid are generated as the fluid jet exits the injector. The memory effect in the form of thickness streaks, corresponding to the location of the inlet holes located upstream in the upper manifold feed channel, are evident on the thin film. Also, the velocity field in the injector channel is influenced by the location of the holes. This nonuniform gas flow across the glass causes a color variation of the coating. Effective mixing of the gas streams is required to treat the hole memory problem. However, premature reaction is to be avoided.