With the advent of electronics technology, various instruments in surface roughness measurements appear sequentially. Errors and erroneous judgment will happen while using unsuitably, due to the operating method and range are not exactly the same. For stylus profilometer, the effects of operating parameters on surface roughness of standard sample and machined elements are presented. Furthermore, small size elements or mirror-like surfaces are measured by scanning electron microscope (SEM) and atomic force microscope (AFM). Experimental results show that the cut-off value is the most significant parameter to Ra, it suggests that the best range for the cut-off value is greater and equal to 0.8mm. The error of Rmax is less than 3% at scanning speed of 0.05, 0.1 and 0.5mm/s, and that within 10% at scanning speed of 2mm/s. Rmax increases with increasing angle of work-stage. The measurement length for standard sample is insignificant to Ra and Rmax. When the surface with curvature is measured, the curvature is removed by the cut-off value for filtering, and the roughness curve is judged whether include peaks and valleys of profile curve, and then the surface roughness is measured by man-made. When the irregular surface is measured, the cut-off value of 0.8mm and higher is selected, and represented surface in the way of separate section or area. SEM and AFM are used to assist in measuring for real roughness value when small size elements or mirror-like surfaces are measured. Variations of roughness of machined elements in polishing are measured finally, results show that Ra, Rq, Rmax, Rz, Skewness will decrease with increasing polishing time, and Kurtosis will increase.

ABSTRACT The ceramic ball bearing has been used to exact machine for its good properties such as heat-resistant, corrosion-resisting, and wear-resisting. Now, the produced expense of ceramic ball is hundred of steel ball because the grinding process must spend much time and money. This study research the effects of eccentricity (e: the distance is between the center of the ball circulation and the center of the spindle), spindle speed, and load on grinding characteristics of ball by using eccentric ultra-precision ball grinding machine which developed by our lab, under saving cost and time, search the optimum operating conditions of this machine, it¡¦s good for industrial circles in the future. Experimental results show that the converged rate of the saturated value for the sphericity is increased with increasing eccentricity. Saturated value of sphericity is sphericity reduced to a steady state. The saturated value of the sphericity is not fully proportional to eccentricity. The relation between eccentricity and saturated value of sphericity are divided two region by one rb, the first region is that sphericity is proportional to eccentricity when eccentricity is 0~rb, and the second region is that sphericity is inverse proportional to eccentricity when eccentricity is rb~2rb. The converged rate of surface roughness (Ra) are negative with increasing eccentricity and the saturated value of the surface roughness (Ra) is higher. The volume removal rate is increased with increasing eccentricity. The converged rate of the saturated value for the sphericity and surface roughness (Ra) are increased with increasing spindle speed and load, and the saturated value are higher. The volume removal rate is also increased with increasing spindle speed and load.

Non-contacting annular seals are internal sealing devices used in rotating machinery, such as multistage centrifugal pumps and compressors. Their design affects both efficiency and rotor stability. Traditional plain and labyrinth seals are being replaced with stators containing different roughness patterns to reduce leakage and enhance rotor response. Several roughened seal experiments with liquid and air have produced leakage data indicating that the friction factor increases as the seal clearance is increased. Simplified models based on bulk flow theory and Moody’s approach to characterize wall friction in pipes cannot explain this outcome. This research is an extension of a 2-D numerical analysis of flat plate experiments with water which found that friction factor of these surfaces is governed by the roughness’ ability to develop high static pressures. An exhaustive 3-D numerical analysis of several experiments with liquid annular seals has been performed using a CFD code. Direct numerical simulations (DNS) of turbulent channel flow and smooth seals were replicated within 1% using Reynolds-averaged Navier-Stokes (RANS) equations and turbulence modeling. Similarly, measured groove seal leakage rates were reproduced within 2%. On the other hand, no turbulence model combination predicts the leakage in most 3-D pattern roughened seals with the same accuracy. Present results reproduce the friction factor ‘plateau’ behavior predicted with the 2-D analysis and observed in the flat plate experiments. They also reproduce the friction-factor-to-clearance indifference behavior, the maximum friction factor observed in a specific roughness pattern size is independent of the actual clearance in a certain Reynolds number range, but clarify the role of the roughness length-to-clearance ratio and the actual roughness size in defining the friction-factor-toclearance proportionality. All simulations indicate that roughened surface area and roughness aspect ratios are the parameters defining the friction factor at a given seal clearance. The roughness pattern size, relevant in determining the friction-factor-to-clearance proportionality, plays a moderate role once the above cited ratios are defined. In any shape and size, shallow patterns are predicted and observed to provide larger friction factors than deep patterns. Predictions also confirm limited experimental data showing that friction factor is affected by the mean flow orientation relative to the roughness pattern. Solving RANS equations is sufficient to model simple seal geometries but might not be enough to replicate turbulent flow in liquid annular seals with roughened surfaces.

The effect of the surface roughness of ice crystals is not routinely accounted for in current cloud retrieval algorithms that are based on pre-computed lookup libraries. In this study, we investigate the effect of ice crystal surface roughness on the retrieval of ice cloud effective particle size, optical thickness and cloud-top temperature. Three particle surface conditions, smooth, moderately rough and deeply rough, are considered in the visible and near-infrared channels (0.65 and 3.75 µm). The discrete ordinates radiative transfer (DISORT) model is used to compute the radiances for a set of optical thicknesses, particle effective sizes, viewing and illumination angles, and cloud temperatures. A parameterization of cloud bi-directional reflectances and effective emittances is then developed from a variety of particle surface conditions. This parameterization is applied in a 3-channel retrieval method for Moderate Resolution Imaging Spectroradiometer (MODIS) data at 0.65, 3.75, and 10.8 µm. Cloud optical properties are derived iteratively for each pixel that contains ice clouds. The impact of ice crystal surface roughness on the cloud parameter retrievals is examined by comparing the results for particles with smooth surfaces and rough surfaces. Retrieval results from two granules of MODIS data indicate that the retrieved cloud optical thickness is significantly reduced if the parameterization for roughened particles is used, as compared with the case of smooth particles. For the retrieval of cloud effective particle size, the inclusion of the effect of surface roughness tends to decrease the retrieved effective particle size if ice crystals are small. The reversed result is noticed for large ice crystals. It is also found that surface roughness has a very minor effect on the retrieval of cloud-top temperatures.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 127-131).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 101-109).

The energy balance of the Earth is regulated in part by ice clouds, which both reflect shortwave solar radiation and absorb infrared radiation from the Earth. These clouds appear frequently worldwide, with up to 70% coverage in tropical regions. The microphysics of ice clouds determines their radiative properties, and is important for accurately predicting the role of ice clouds in Earth’s energy balance. However, describing the microphysics of ice clouds remains a challenging problem, especially with regard to the shape of ice particles and the degree of ice particle surface roughening. In-situ studies have found evidence for ice surface roughness and have found many complex ice geometries; however, these studies are limited spatially and temporally. An approach which allows large-scale analysis is to retrieve these properties via theoretical modeling using satellite observations of polarized reflectance from ice clouds, since polarized reflectance is sensitive to the shape and roughness of ice particles. The theoretical model requires the scattering properties of simulated ice particles. These properties are obtained for 10 different ice shapes and 17 different levels of surface roughness. Simulations are performed for 3 different effective ice particle diameters: 30, 60 and 90 μm. Overall, the retrieved shape is dominated by the compact aggregate of columns. Although the exact composition of shapes varies from month to month, the compact aggregate of columns remains the most commonly retrieved shape. The retrieved roughness varies from moderately rough at σ = 0.1 to severely rough at σ = 0.5. Retrieved roughness varies more than shape, and smooth surfaced ice is most prominent in January. Tropical regions tend to have ice particles that are more roughened, while the midlatitudes and polar regions tend to have more smooth ice. In almost all cases, roughened ice represents > 60% of the total retrievals. The asymmetry parameter inferred from the retrieval of ice particle shape and roughness has a mean value near 0.77, with only small differences based on assumed ice effective diameter. The median value of the asymmetry parameter has a nearly constant value of approximately 0.75.

In this thesis, the effects of roughness on turbulent boundary layers are investigated by both the experimental and analytical methods. Two aspects of roughness are investigated, including the similarity between the smooth and rough turbulent boundary layers, and the characteristics of the flow over the step changes in roughness. Based on the data from the thesis of Akinlade (2005), the validity of three different kinds of outer scales is examined for the defect law in the context of smooth surface and three different types of rough surfaces. Furthermore, a mathematical relation is derived to further investigate the roughness effects. For the second topic, experiments were performed on a smooth-rough-smooth transition in a wind tunnel using a boundary layer Pitot tube. In addition, the growth rates of internal boundary layer thicknesses are determined using the method of Antonia and Luxton (1971, 1972), and the results are compared with the previous studies.

Thesis (M.S.)--University of Michigan, 1963.

Thesis (M.S.)--University of Michigan, 1963.