Stagnation density

This states that the sum of the velocity pressure 0.5pv plus the static pressure / the total pressure, is constant along a streamline. In the case of standard air density (1.2 kg m ), 0.5pv becomes 0.6v. When a Pitot-static tube is immersed into the flow, as in Fig. 12.19, the velocity at the stagnation point at the tube nose is f = 0 and the local static pressure equals the total pressure p,. The flow static pressure p, is measured a short distance downstream from the surface of the tube. The flow velocity is obtained by applying Eq. (12.27) ... 

In design considerations for Thermonized process lines, temperatures may be determined by the Stagnation Method. The calculations involved in this method are based on static conditions where process fluid flow is not present, and are independent of the viscosity, density and thermal conductivity of the process fluid. The process temperature may be calculated from the following relationship ... 

Figure 4.1.2 is a photograph of a coimterflow burner assembly. The experimental particle paths in this cold, nonreacting, counterflow stagnation flow can be visualized by the illumination of a laser sheet. The flow is seeded by submicron droplets of a silicone fluid (poly-dimethylsiloxane) with a viscosity of 50 centistokes and density of 970 kg/m, produced by a nebulizer. The well-defined stagnation-point flow is quite evident. A direct photograph of the coimterflow, premixed, twin flames established in this burner system is shown in Figure 4.1.3. It can be observed that despite the edge effects.

Weder s experiments were carried out with opposing body forces, and large current oscillations were found as long as the negative thermal densification was smaller than the diffusional densification. [Note that the Grashof numbers in Eq. (41) are based on absolute magnitudes of the density differences.] Local mass-transfer rates oscillated by 50%, and total currents by 4%. When the thermal densification dominated, the stagnation point moved to the other side of the cylinder, while the boundary layer, which separates in purely diffusional free convection, remained attached. 

The above-mentioned technology and structure provide advantages for the Improved B-l electrolyser in performance and reliability even under high current density. Good electrolyte distribution and no gas stagnation in each chamber, smooth discharge of gas and liquid, and low ohmic drop are necessary to overcome the difficulties of high current density operation. 

Equation (4.4), which connects the known variables, unbumed gas pressure, temperature, and density, is not an independent equation. In the coordinate system chosen, //, is (lie velocity fed into the wave and u2 is the velocity coming out of the wave. In the laboratory coordinate system, the velocity ahead of the wave is zero, the wave velocity is uh and (u — u2) is the velocity of the burned gases with respect to the tube. The unknowns in the system are U, u2, P2, T2, and p2. The chemical energy release is q, and the stagnation adiabatic combustion temperature is T, for n-> = 0. The symbols follow the normal convention. 

It is obvious that the entropy change will be positive in the region Mi > 1 and negative in the region Mi < 1 for gases with 1 < y < 1-67. Thus, Eq. (1.46) is valid only when Ml is greater than unity. In other words, a discontinuous flow is formed only when Ml > 1. This discontinuous surface perpendicular to the flow direction is the normal shock wave. The downstream Mach number, Mj, is always < 1, i. e. subsonic flow, and the stagnation pressure ratio is obtained as a function of Mi by Eqs. (1.37) and (1.41). The ratios of temperature, pressure, and density across the shock wave are obtained as a function of Mi by the use of Eqs. (1.38)-(1.40) and Eqs. (1.25)-(1.27). The characteristics of a normal shock wave are summarized as follows ... 

Equation (5-8) is applicable in the range v2stagnation plane W (x) =0. The approximation in eq (5.8) is based on the observation that in this range of densities, temp T decreases during isentropic expansion at about the same rate that increases and the product (T/3) is therefore approx constant. The integral v2... 

F/g 6.8 Nondimensional velocity, temperature, and density profiles for finite-gap stagnation flow at various values of the temperature difference between the inlet manifold and the stagnation surface. In all cases the inlet temperature is 7 n = 300 K, the Reynolds number is Re = 100, and the Prandtl number is Pr = 0.7. 

Equation 11.131 assumes that the total surface site density T is constant. Section 17.7.1 uses the equation above in the formulation of a transient stagnation flow problem, for example. 

The integral Eq. (59) together with the surface shape Eq. (56) would determine the flame propagation velocity along the tube axis as a function of the normal flame velocity and the density ratio a. The width of the stagnation zone could be derived by integration... 

Numerical experiments provided the critical EPR density Acr 2.5. No stagnation is formed if A < Acr the profiles U(z) in the EPR bottom tend to a constant slop, and r0 = r(0) = const + 0. Stagnation begins at a certain distance Xs (Fig. 3.8) if A > Acr and then ranges to infinity. At this distance, the shear on the wall reaches the value r(Xs, 0) 0, and the computing program loses its stability. 

The thermal stagnation zone can happen in the lower part of the droplet layer, over which t(z) has almost reached its possible limit, and so there is no cooling of droplets over the lower part of their trajectories. This means that the density of droplets is too high, and the efficiency of the cooling system can be improved by arranging the spraying nozzles to reach a lesser density of droplets. 

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