Entry conditions

BOUNDARY LAYER THEORY APPLIED TO PIPE FLOW 11.5.1. Entry conditions 

An approximate experimental expression for the inlet length Lp for laminar flow is  

At the inlet to the pipe the velocity across the whole section is constant. The velocity at the pipe axis will progressively increase in the direction of flow and reach a maximum value when the boundary layers join. Beyond this point the velocity profile, and the velocity at the axis, will not change. Since the fluid at the axis has been accelerated, its kinetic energy per unit mass will increase and therefore there must be a corresponding all in its pressure energy. 

Thus the kinetic energy per unit mass of the fluid at the axis inlet = u  

Thus the fall in pressure due to the increase of velocity of the fluid = 

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Fig. 6.2 shows a simplified diagram of the basic STIG plant with steam injection S per unit air flow into the combustion chamber the state points are numbered. Lloyd 2 presented a simple analysis for such a STIG plant based on heat input, work output and heat rejected (as though it were a closed cycle air and water/steam plant, with external heat supplied instead of combustion and the exhaust steam and air restored to their entry conditions by heat rejection). His analysis is adapted here to deal with an open cycle plant with a fuel input/to the combustion chamber per unit air flow, at ambient temperature To, i.e. a fuel enthalpy flux of/7i,o. For the combustion chamber, we may write... 

If the procedures were not regularly updated or were otherwise incorrect, or if training was inadequate, PI errors could occur. P2 errors would often arise as a result of misdiagnosing a situation, or if the entry conditions for executing a sequence of operations were ambiguous or difficult to assess and therefore the wrong procedure was selected. It is important to note that if a planning error occurs, then this implies that a detailed analysis needs to be conducted of the alternative course of action that could arise. 

For the baseline process, the experimental data and the numerical simulations fit quite well. The entry pressure and temperature to the metering section of 22 MPa and 190 °C are very reasonable for this resin and application. These entry conditions will be used to design the new process. 

Entry Conditions Reaction time Yield Reference... 

The plasma jet does not exactly simulate re-entry conditions, but it is capable of supplying approximately the same gas temperatures and heating rates to a specimen nose cone. 

Step 11 Go back and plot along the points (r, z) = (0,2) and (0.5,2) or on boundary 3 to obtain Figure 10.5. This figure shows the outlet velocity. The exact solution is a quadratic function of position, which is satisfied in Figure 10.5. However, you also expected a peak value of 2.0. The peak value is not 2.0 because of the slight error in the entry conditions. What is true is that the flow rate out equals the flow rate in, which is slightly less than you desired due to the bump in the inlet profile. This discrepancy decreases as you refine the mesh. 

Entry Condition Changes in parameter list permitted Name of condition or comment... 

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