Investigation of effects of tire contour on aerodynamic characteristics and its optimization

Reducing the aerodynamic drag is one of the most important approaches for the development of energy-saving and environment-friendly automobiles. The tire contour has a great influence on the aerodynamic characteristics of automobiles. The aim of this study is to investigate the influence of the tire contour design parameters on the aerodynamic characteristics around a closed wheel, and obtain the optimized tire contour to reduce the automobile aerodynamic drag. A passenger car tire 185/65R14 was selected to conduct the wind tunnel test, and the surface pressure coefficients were used to validate the simulation model established using the detached eddy simulation (DES) model. To decrease tire drag, and taking the upper sidewall height, the tread radii, the tread width, and the transition arc radius of the shoulder as four design variables of contour, a combination of the Latin hypercube experimental design, the Kriging surrogate model, and the adaptive simulated annealing (ASA) algorithm were used to optimize the tire contour design parameters. The changes of flow field around the tire, including the velocity, turbulent kinetic energy, and pressure field were compared and analyzed for further understanding of the drag reduction mechanism. It is found that the aerodynamic drag coefficient of the optimized tire is reduced by 14.5%, and the aerodynamic coefficient drag of the car using the optimized tire is reduced by 7%. The present results are expected to provide useful information for designing new tire structures and improving the aerodynamic performance of the automobile.

Bioinspired Divide-and-Conquer Design Methodology for a Multifunctional Contour of a Curved Lever

In this study, we propose a bioinspired design methodology for a multifunctional lever based on the morphological principle of the lever mechanism in the Salvia pratensis flower. The proposed divide-and-conquer contour design methodology does not treat a lever contour as a single curve that satisfies multiple functions. Rather, the lever contour combines partial contours to achieve its assigned subfunction. This approach can simplify the complex multifunctional problem in lever design. We include a case study of a lever utilized in a compact variable gravity compensator (CVGC) to explain the methodology in more detail. In the case study, four partial contours were designed to satisfy three types of functional requirements. The final design for the lever contour was manufactured and verified with visual measurement experiments. The experimental result shows that each partial contour successfully achieved its subfunctions.

Clinical Methodology Quantifying the Emergence Profile Contour For Immediate Provisionalization: A Proposed Mathematical Model

Identifying the ideal position of the final restoration prior to implant surgery is essential for optimal aesthetics. Study of the emergence contour design of implant restorations has been limited. The aim of this report is to compile the factors which affect the final esthetic outcome and integrate those factors into an easy-to-use model. This geometric model includes a linear distance created by the placement of an implant platform in relation to the free gingival margin, and a circle representing the emergence profile to create an Emergence Curve. If this model is evaluated and available, a practitioner can make appropriate decisions based on 3-dimensional immediate implant concepts

Development of an automated non-axisymmetric endwall contour design system for the rotor of a 1-stage research turbine – Part 2 computed and experimental results

In this paper, we present the computed flow results for those endwall designs produced using the automated non-axisymmetric endwall design procedure and target objective functions detailed in Part 1 of this paper, and where available, compare these with experimental measurements made using the CSIR low-speed research turbine used as the test case for the designs. Experimental measurements were taken immediately aft (X3) as well as downstream (X4) of the rotor row using a drilled 5-hole elbow probe, and both the computed as well as physical results were processed identically to ensure as high a degree of comparability between the computed and physical datasets. For the two initial cases (the η tt- and C ske-based designs), the results of the experiments confirmed the predictions of the simulations, although unexpected flow separations which were not predicted by the computational fluid dynamics (CFD) resulted in poorer agreement for the two remaining contoured cases. In general, the results of the CFD, as confirmed by the experiment, showed that the best metric for the design of the endwall contours for this rig was that based on the rotor total–total efficiency although importantly, the well-known coefficient of secondary kinetic energy ( C ske), even when formulated using a reasonably simple approach, was able to produce closely competitive results to the efficiency-based metric. These findings are significant firstly because, to date, the use of efficiency is not widespread for the design of non-axisymmetric endwall contours, and secondly, because in cases where the efficiency might be difficult to measure and/or predict, the C ske may form a robust if only slightly less effective alternative.

INFLUENCE OF THE METHOD OF FASTENING OF THE STRESSLESS TAGS TO THE THRESHOLD PROCESS

Introducing chipless taps into production it is necessary to take into account factors arising from the specifics of the method and factors affecting economic efficiency. Significant effect from the introduction of the machine method of manufacturing threaded holes in stainless steels with brushless taps can be obtained only if the complex of measures is observed, related to the choice of the optimum hole diameter and the quality of preparation of the hole for the thread, the choice of mounting the tap on the machine, the speed of thread extrusion, coolant equipment and others. A new contour design has been proposed in the paper to prevent damage to the instrument for the manufacture of internal threaded holes. In addition, the design allows to replace quickly the instrument to another size. The designed construction of the cartridge ensures the centering of the tool over the hole being machined and ensures the transmission of torque of the required size. Analytical dependencies and computational schemes that ensure the operability of the device are derived.