Erosive ratio

Existing exterior exposure records were reviewed with respect to visual erosion ratios. 

Fig. 13.6 Erosive ratio and threshold velocity of erosive burning for high-energy, reference, and low-energy double-base propellants, showing that the low-energy propellant is most sensitive to the convective heat flux.

Fig.13.8 Erosive burning model calculation and experimental data for erosive ratio as a function of gas flow velocity or mass flow velocity.

The pressure peaks observed in the combustion tests shown in Fig. 14.19 are computed as a function of L/D as shown in Fig. 14.20. The peak pressures computed by means of the Lenoir-Robillard empirical equation are confirmed by the measured pressure at the head-end of the motor. It is evident thatp values predicted without erosive burning are significantly lower than the measured maximum pressures. Fig. 14.21 shows the erosive ratio, 8 = r/to, as a function of the mass flow rate per unit cross-sectional area in the port, G. The erosive ratio increases with increasing Mach number in the port at constant L/D. 

Fig. 14.21 Erosive ratio versus mass flow rate in unit cross-sectional area of the port.

The erosion of graphite in nozzle appHcations is a result of both chemical and mechanical factors. Changes in temperature, pressure, or fuel-oxidizing ratio markedly affect erosion rates. Graphite properties affecting its resistance to erosion include density, porosity, and pore size distribution... 

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

In disc form, when prepared by compression molding, the more hydrophobic polymers, PCPP and PCPP-SA, 85 15, displayed constant erosion kinetics over 8 months. By extrapolation, 1-mm-thick discs of PCPP will completely degrade in over 3 years. The degradation rates were increased by copolymerization with sebacic acid. An increase of 800 times was observed when the sebacic acid concentration reached 80%. By altering the CPP-SA ratio, nearly any degradation rate between 1 day and 3 years can be achieved (4). 

Most of the properties of a dental silicate cement are affected by preparative variables, particularly the powder/liquid ratio (Jorgensen, 1963 Wilson Batchelor, 1967b). Increase in the powder/liquid ratio accelerates set and increases strength and resistance to erosion (Figure 6.21). Temperature and, to a lesser extent, humidity during mixing have some effect, but chiefly they affect setting time. 

Agitator autoclave tests can be used as screening tests despite the more intensive localized corrosion attack and the generally greater erosion rates. This test method elucidates the influences of certain test parameters including temperature, H2S/CO2 ratio, and flow [564]. 

A characteristic parameter of the process is the ratio of the overall rate of erosion relative to the overall rate of rupture given by... 

Figure 26.34 can be used to find the soil loss ratio due to the slope of the site as used in the Universal Soil Loss Equation. Loss from wind erosion can be determined by the following equation ... 

Negrel Ph, Allegre CJ, Dupre B, Lewin E (1993) Erosion sources determined by inversion of major and trace element ratios and strontium isotopic ratios in river water the Congo Basin case. Earth Planet Sci Lett 120 59-76... 

---