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Momentum losses

Blade loading or diffusion loss. This loss is due to the type of loading in an impeller. The inerease in momentum loss eomes from the rapid inerease in boundary-layer growth when the veloeity elose to the wall is redueed. This loss varies from around 7% at a high-flow setting to about 12% at a low-flow setting. [Pg.330]

Consider now the case where the axial heat transfer due to the temperature gradient is negligible compared to the heat transfer from the capillary wall and the friction caused by the velocity gradient in the x-direction is negligible compared to the momentum losses at the fluid-wall interface. [Pg.360]

The interaction of dispersing clouds with vapor fences is a complex physical process. When a flow meets an obstruction, turbulence levels are increased downstream because of vorticities introduced into the flow field, and increased velocity gradients are induced by flow momentum losses. Detailed modeling of such a process is very difficult and requires a combination of small-scale experiments and computational fluid dynamics. [Pg.106]

Similar to ISS, except the main focus is on depth-profiling and composition. The momentum transfer in back-scattering collisions between nuclei is used to identify the nuclear masses in the sample, and the smaller, gradual momentum-loss of the incident nucleus through electron-nucleus interactions provides depth-profile information. [Pg.18]

The flow distribution superiority of the 7l-flow configuration has a simple physical interpretation. When frictional losses in the feed channel are low, pressure increases in the flow direction due to momentum loss. In the exit channel, the opposite is true. Thus in Z-flow a large radial pressure drop occurs at the exit end of the reactor, while a much smaller one occurs at the entrance end. This relatively large gradient in radial pressure drop is essentially what causes the flow maldistribution. In 7l-flow, however, due to the opposite flow of feed and product streams, pressure increases in the same direction in both channels and results in a more uniform pressure drop, and consequently, fluid distribution. [Pg.321]

Pick s First Law is (momentum losses due to molecule-molecule collisions) ... [Pg.352]

The constancy of the friction coefficient is a strong indicator of the importance of slip flow at the pore wall in micropores. Further, calculations showed that the above values of the friction constant are closely consistent with momentum transfer arguments. For this we consider the frictional force as arising from the momentum loss on diffuse reflection at the wall leading to... [Pg.107]

For simplicity we will ignore momentum loss due to meander turns and assume that the channel is straight with the axis directed along z. Consider a cathode channel. Due to the electrochemical reaction each oxygen molecule is replaced with two water molecules in the flow. The continuity equation, therefore, reads (In [192]... [Pg.514]

At higher temperature the separation factor increases because the mean free path increases and consequently less momentum loss is expected for H2. The effect is stronger at lower P value, and at P, = 0.10 and P = 7 atm the values of... [Pg.366]

It can be seen from Fig. 20 that Mq 10 5 M0 yr 1 for the considered 60 M0 sequences. It should be stressed that, although the model is simplified and the analysis only qualitative, the derived mass loss rate at the H-limit is expected to be even quantitatively correct, since it is established by the rate of angular momentum loss which is associated with the mass loss. Once the critical rotational velocity is reached, the angular momentum loss rate is set by the expansion time scale of the star (i.e. its speed in the HR diagram) but does not depend on the value of the critical velocity. [Pg.70]

The waves caused by small wind velocities are damped by a slick. The momentum loss of the waves induces a wave stress gradient acting on the surface film (Foss 2001). This results in a compacting influence on the upwind side of the slick. [Pg.73]

Equation 20 shows that a porous medium is permeative, that is, a shear factor exists to account for the microscopic momentum loss. Our preliminary study recently reveals that, however, a porous medium is not only permeative but dispersive as well. The dispersivity of a porous medium has been traditionally characterized through heat transfer (in a single- or multifluid flow) and mass transfer (in a multifluid flow) studies. For an isothermal single-fluid flow, the dispersivity of a porous medium is characterized by a flow strength and a porous medium property-de-pendent apparent viscosity. For simplicity, we discuss the single-fluid flow behavior in this chapter without considering the dispersivity of the porous medium. [Pg.242]

Inlet Temperature Effect. - Pressure drop increases with inlet temperature as shown in Figure 11. If velocity is kept constant, pressure drop due to wall friction is reduced with inlet temperature, but momentum loss, because of the increase in conversion efficiency as shown in Figure 7, would increase. Thus, pressure drop increases with inlet temperature. Keeping mass flow constant, pressure drop increases as velocity increases with a constant conversion efficiency as shown in Figure 7. [Pg.332]

According to the power balance, Eq. (38), the mean power gain from the electric field is compensated for by the mean power loss in collisions, and this happens for any given gas and its specific atomic or molecular data and for any reduced field strength E/N. An analogous compensation occurs in the momentum balance, Eq. (39), between the mean momentum gain from the field and the mean momentum loss in collisions. [Pg.34]

The behavior of the individual terms in the momentum balance (right) is similar to that in the power balance. Now the normalized momentum loss in elastic collisions r (z)/I oo) oscillates around the oscillating momentum gain /(z)// (oo), and the somewhat lesser deviations between these quantities are compensated for to a large extent by the normalized source term d/dz) [(2/3m )u z)]/P oQ) of the momentum balance (dotted-dashed curve) containing the spatial derivative of the mean energy density , (z). [Pg.68]

A second rapid increase in the flame speed occurs at H2 25% for both tubes. This corresponds to a transition to the detonation regime. The detonation velocity in the obstacle field is typically about 1500 m/sec and is practically independent of the H2 concentration up to H2 - 45%. For higher H2 concentrations, the detonation velocity abruptly drops back to the values for deflagration speeds of the order of 800 m/sec. The severe pressure Cor momentum) losses due to the presence of the obstacles accounts for the sub-Chapman-Jouguet detonation velocities observed. The normal velocities are about 2000 m/sec as observed in smooth tubes for H2 concentrations in the range (i.e., 25% H2 45%). [Pg.125]

Because of the high gas velocities, solids loading ratios, and momentum loss in the collision zone, the pressure loss in ISDs is much greater than in pneumatic dryers, but it is comparable with that of fluidized and spouted bed dryers [44,45], The impinging stream configurations can, however, compete in various aspects with the classical systems for drying of particulates and pastes (Table 21.11). [Pg.454]


See other pages where Momentum losses is mentioned: [Pg.502]    [Pg.167]    [Pg.175]    [Pg.238]    [Pg.316]    [Pg.97]    [Pg.227]    [Pg.433]    [Pg.215]    [Pg.285]    [Pg.523]    [Pg.352]    [Pg.201]    [Pg.36]    [Pg.39]    [Pg.115]    [Pg.282]    [Pg.368]    [Pg.326]    [Pg.31]    [Pg.42]    [Pg.49]    [Pg.50]    [Pg.54]    [Pg.37]    [Pg.131]    [Pg.760]    [Pg.331]   
See also in sourсe #XX -- [ Pg.31 ]




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