Mixed flows

For a complex fluid, the stress depends not only on whether the flow is a shearing, extensional, or mixed type, but also on the whole history of the velocity gradient. Thus, the 

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Centrifugal, including radial, mixed flow, and axial flow designs... 

Axial flow impeller (propeller) or mixed flow type (horizontal or vertical)... 

Turbine Pumps The term Turbine pump is applied to units with mixed-flow (part axial and part centrihigal) impellers. Such units are available in capacities from 20 mVh (100 gal/min) upward for heads up to about 30 m (100 ft) per stage. Turbine pumps are usually vertical. 

FIG. 10-46 Vertical multistage turbine, or mixed-flow, pump. 

Whereas the total dynamic head developed by a centrifugal, mixed-flow, or axial-flow pump is uniquely determined for any given flow by the speed at whicdi it rotates, positive-displacement pumps and those which approach positive displacement will ideally produce whatever head is impressed upon them by the system restrictions to flow. Actually with slippage neglecTed, the maximum head attainable is determined by the power available in the drive and the strength of the pump parts. An automatic relief valve set to open at a safe pressure... 

There are three types of mixing flow patterns that are markedly different. The so-called axial-flow turbines (Fig. 18-3) actually give a flow coming off the impeller of approximately 45°, and therefore have a recirculation pattern coming back into the impeller at the hub region of the blades. This flow pattern exists to an approximate Reynolds number of 200 to 600 and then becomes radial as the Reynolds number decreases. Both the RlOO and A200 impellers normally require four baffles for an effective flow pattern. These baffles typically are V12 of the tank diameter and width. 

FIG. 23-13 The two limiting flow patterns with the same RTD. a) Segregated flow, in which all molecules of any exit stream have the same residence time, (h) Maximum mixed flow, in which all molecules of an external stream with a certain life expectation are mixed with all molecules of the internal stream that have the same life expectation. 

Impeller Radial Flow. Impeller Mixed Flow. Vertical Regenerative Turbine. 

The inward-flow radial turbine has many components similar to a centrifugal compressor. There are two types of inward-flow radial turbines the cantilever and the mixed-flow. The cantilever type in Figure 1-34 is similar to an axial-flow turbine, but it has radial blading. However, the cantilever turbine is not popular because of design and production difficulties. 

Mixed-Flow Turbine. The turbine as shown in Figure 1-35, is almost identical to a centrifugal compressor—except its components have different functions. The scroll is used to distribute the gas uniformly around the periphery of the turbine. 

Boyce, M.P., and Bale, Y.S., Diffusion Loss in a Mixed-Flow Compressor, Intersociety Energy conversion Engineering conference, San Diego, Paper No. 729061, September 1972. 

Dallenback F., The Aerodynamic Design and Performance of Centrifugal and Mixed-Flow Compressors, SAE International Congress, January 1961. 

Stanitz, J.D., Two-Dimensional Compressible Flow in Conical Mixed-Flow Compressors, NACA TN-1744, 1948. 

Wu, C.H., A General Theory of Three-Dimensional Flow in Subsonic and Supersonic Turbomachines of Axial, Radial, and Mixed-Flow Type, NACA TN-2604, 1952. 

The radial-inflow turbine has many eomponents similar to those of a eentrifugal eompressor. Flowever, the names and funetions differ. There are two types of radial-inflow turbines the eantilever radial-inflow turbine and the mixed-flow radial-inflow turbine. Cantilever blades are often two-dimensional and use nonradial inlet angles. There is no aeeeleration of the... 

Figure 8-4. Mixed-flow-type radial-inflow turbine.

Abidat, M.I., Chen, H., Baines, N.C., and Firth, M.R., 1992. Design of a Highly Loaded Mixed Flow Turbine, Proc. Inst. Mechanical Engineers, Journal Power 8 Energy, 206 95-107. 

Arcoumanis, C., Martinez-Botas, R.F., Nouri, J.M., and Su, C.C., 1997. Performance and Exit Flow Characteristics of Mixed Flow Turbines, International Journal of Rotating Machinery, 3(4) 277-293. 

Wallace, F.J., and Pasha, S.G.A., 1972, Design, Construction and Testing of a Mixed-Flow Turbine. 

Centrifugal Impeller 60° mixed-flow Impeller 4S° mixed-flow Impeller... 

Figure 1-13. Comparison of radial- and mixed-flow compressor impellers.

Meiidional tiow vector, 152 Meter run requirements, 431 Method of piping, 190 Michell bearing, 201 Mini lube system, leeiprocating, 78 Mixed flow, II, 14 Mixed-flow impeller, 14 Mixture compressibility, 20 Mode shape,s, 386, 388 Moisture corrections, 2 Mole, U ... 

For N equal size mixed flow reaetors in series, a general equation... 

Figure 5-26. Maximization of reotangle applied to find the optimum intermediate oonversion and optimum sizes of mixed flow reaotors in series.

Equation 9-15 gives the conversion expression for the second order reaction of a macrofluid in a mixed flow. An exponential integral, ei(a), which is a function of a, and its value can be found from tables of integrals. However, the conversion from Equation 9-15 is different from that of a perfectly mixed reactor without reference to RTD. An earlier analysis in Chapter 5 gives... 

Figure 6.6 and Tables 6.4-6.6 give ranges for local thermal discomfort parameters for the three categories listed in Table 6.3. The acceptable mean air velocity is a function of local air temperature and turbulence intensity. 7 he turbulence intensity may vary between 30% and 60% in spaces with mixed flow air distribution. In spaces with displacement ventilation or without mechanical ventilation, the turbulence intensity may be lower. 

German guidelines base the division on the resulting airflow pattern within the room rather than distribution methods. They suggest that airflow patterns be divided into four categories hall-filling mixed flow zonewise mixed flow low-momentum, low-turbulence flow for the air supply in the work region and zonewise displacement ventilation. 

Mixed flow, actual An actual flow pattern in an enclosure resulting in the air being mixed to such an extent that conditions are almost the same at every point in the occupied zone. 

Mixed flow, ideal The flow pattern in an eticlosure in which the air is completely mixed and has the same conditions at every point. 

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