Impact number

Stoss-welle, /. percussion wave, impact wave, -widerstand, m. resistance to shock, -zahl, /. number (A collisions, impact number. -zUn-der, m. percussion fuse, stottern, t.i. stutter. 

This number is conceptually an energy ratio, but independent of the interface heat extraction rate and thus the contact area. Since the interface heat transfer is assumed to control the solidification process of an impacting droplet, the choice of a dimensionless number should involve an evaluation of the influence exerted by this key factor. Therefore, the use of this newly defined dimensionless number is limited to an initial decision on which of the Impact number and the Freezing number is most appropriate for the application to a given material system at a know impact velocity. 

Impact Number j qU0 2Ach TL-T ) Compare kinetic energy transfer rate to heat extraction rate Matson et al. [409]... 

For the attrition experiments approximately 25 g of polymer particles were used. After three, six and nine consecutive impacts with a velocity of 40 m/s, the attrition rate A was determined as the relative loss of mass (see Eq. (1)). This procedure was necessary since the attrition rates for some polymer classes were not measurable with satisfying accuracy for lower impact numbers. Since the attrition process is highly statistical, each experiment was repeated three times. This also holds for the other experimental setups. In the following diagrams, the median values of these three repeated experiments are plotted with the standard deviations as error bars. For all experiments, the attrition rate A was calculated according to Eq. (1), where M denotes the initial particle mass. Ma is the mass of particles at the initial size after the attrition experiment. 

Express the inertial impaction number ip j in terms of particle diameter dp. The relationship... 

Related Calculations. In situations where the particles are so small that their size approaches the length of the mean free path of the fluid molecules, the fluid can no longer be regarded as a continuum that is, the particles can fall between the molecules. That problem can be offset by applying a factor, the Cunningham correction factor, to the calculation of the inertial-impact-number expression in step 2. 

As defined by the Institute of Scientific Information (Ref. 7), the impact number is the average number of times articles in a given journal are cited by subsequent authors each year. For example, articles in a journal with an impact of 4 are cited by subsequent papers twice as frequently as are articles in a journal with an impact of 2. The premise is that more significant work IS cited more often. The impacts reported in this column are for 1992, which is the most recent year for which data are available. 

Measuring loads in high speed tests is difficult because of the short times involved and the presence of transient effects from stress waves. The more simple method which has been developed in both the Izod and Qiarpy tests is to break the spedmoi with a pendulum and measure the energy absorbed. Some form of scaling parameter from the specimen dimmsions is then applied and an impact number derived. The practical utility of these numbers is beyond question but they have many, weU known, drawbacks. In particular, the nund)ers are geometry dependent and do not agree, for example, between the Izod and Charpy tests. 

The reader should note that cp and p are modified inertial impaction numbers based on the cake and fabric, respectively. Unfortunately, this key equation has been totally ignored by responsible EPA individuals in this field. Taxpayers dollars continue (for over a dozen years) to be provided to contractors whose research efforts have produced little, if any, usable results in developing quantitative equations to describe collection efficiency. 

Figure 6.62 Variation of the impact load with impact number for both G1 and G2 specimens...

Figure 6.63 Variation of deflection with impact number...

In safety-critical environments it can be agreed that items that handle safety aspects are always placed in quadrant I, regardless of their estimated likelihood and impact numbers. Note that this is not needed by default, as other precautions are already taken for safety issues (results from FMEA or safety hazard analsysis). 

Estimate the incident impacts on people, environment and property. The effect models take the incident outcomes of step 2 and determine the direct impacts— number of individuals affected, property damage, etc. Effect models are discussed in Chapter 4. 

The impact number e is chosen to be e = 0.17. The remaining data is given in Table 6.8. Thus we have the following types of discontinuities in this example ... 

The methodology for impact assessment is widely accepted and ISO standards have been established to compare and quantify the various weighing factors. The assessment consists of weighing the classes to integrate the environmental profiles such as effects on GHG emission, ozone depletion, acidification, or eutrophication. It is however unrealistic to desire unification into one environmental impact number for widely diverse ecological and economical effects. 

The CFD model is employed to simulate the penetration behaviour of a cubic particle into a liquid droplet. The ratio of the cube width (a, pm) to droplet diameter (d, pm) covers 20 120, 20 240, and 20 +oo, where +oo means a flattened liquid surface. Figure 18.43 shows the 3D computational domain and the arrangement of solid particle and liquid droplet. Three different particle orientations, that is I, II. and III, are considered. Both head-on collision and off-centre collision are investigated. As in droplet-droplet collision studies [47], an impact number B is defined to describe the off-centre degree during particle-droplet collision, as follows ... 

Figure 18.49 shows two cases of off-centre collision with different impact numbers B). In the first case, the particle completely penetrates into the droplet in the second case, the particle partially penetrates into the droplet, and then is ejected by droplet surface. It can be fotmd that the penetration process for both cases is characterized by the particle rotation. In the case of partial penetration, if the particle spins counterclockwise to penetrate the droplet, it will be ejected from the liquid surface with a clockwise rotation. Unlike in a collision system of two equal-sized droplets [47], a particle of small inertia imposes negligible influence on the motion state of a large droplet. Figure 18.50 (left) shows the regime map of... 

Fig. 18.50 Off-centre collision (/ ) regime map at B = 0.2 (right) shift of regime boundary with variation of impact number from B = 0 to B = 0.2...

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