Stagnation state

It is implied that the states referred to in any cycle are stagnation states but as velocities are assumed to be low, stagnation and static states are virtually identical. 

The simple approach described before involves approximations, particularly to obtain the stagnation pressure loss. The full determination of pf) m (7 o)5m from the various equations given above can lead to an approximation for the downstream entropy (.vsni). using the Gibbs relation applied between stagnation states. 

Here the temperature ratio T/To has been replaced using equation (14.25), while we have also assumed that the pressure and specific volume in the stagnation state are related to temperature by ... 

Once the two thermodynamic variables, pressure and temperature, have been defined, it is possible to evaluate all the other thermodynamic variables characterizing the stagnation state. For example, stagnation specific volume emerges from equations (14.43) and (14.44) as... 

In his paper Reaction tests of turbine nozzles for supersonic velocities , Keenan (1949) presented the results of experimental tests on five turbine nozzles one is convergent-only and four are convergent-divergent. He measured the outlet velocity using a force balance and then calculated the velocity coefficient as the ratio of measured velocity downstream of the nozzle, c, to the velocity, cu that would occur following an isentropic expansion from the stagnation state at nozzle inlet to the exhaust chamber pressure, pi ... 

Atmospheric haze can occur over regions of several thousand square kUometers, caused by the oxidation of widespread SO2 and NO2 to sulfate and nitrate in relatively slow-moving air masses. In the eastern United States, large air masses associated with slow- moving or stagnating anticyclones have become sufficiently contaminated to be called hazy blobs. These blobs have been tracked by satellites as they develop and move across the country (15). 

A survey by national park personnel indicates that large areas of the United States are subject to varying degrees of visibility degradation (1). The middle portion of the eastern half of the country and the Florida Gulf Coast are subject to widespread hazy air masses associated with stagnation conditions. Large portions of the western half of the country are subject... 

Korshover (3) studied stagnating anticyclones in the eastern United States over two periods totaling 30 years. He found that for stagnation to occur for 4 days or longer, the high-pressure system had to have a warm core. Korshover s criteria included a wind speed of 15 knots or less, no frontal... 

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) ... 

This flow field can be maintained in a steady state, at least in the Eulerian sense, either by use of a four-roll mill [18] as in Figure 2.8.4(a) or by means of opposed jet flow as in Figure 2.8.4(b). However, it is important to note that the flow is still transient in the Lagrangian sense. That is, pure planar extension is confined to the central stagnation... 

Two particularly useful equations can be derived by applying the thin concentration boundary layer approximation to steady-state transfer from an axisymmetric particle (L2). The particle and the appropriate boundary layer coordinates are sketched in Fig. 1.1. The x coordinate is parallel to the surface x == 0 at the front stagnation point), while the y coordinate is normal to the surface. The distance from the axis of symmetry to the surface is R. Equation (1-38), subject to the thin boundary layer approximation, then becomes... 

Dunkle (Ref 40) points out that total pressure is also known as stagnation pressure and is equal to the sum of static pressure and dynamic pressure. Both of these are exerted by gases. More detailed explanation is given in Ref 40, p 32. He also states that in the reaction between A1 K chlorate, mentioned above, the products formed at the temperature of explosion are gaseous KC1, AlO, A O and oxygen. The A Oj does not form until the products cool... 

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