![]() The lower rise at 15° is probably due to the start of separation of the boundary layer. Otherwise you need to build a rather elaborate model to account for the flow of gases, the flow of energy energy and the chemical reactions that take place. In your gun barrel problem we have no option but to assume reversibility. Figure 2 shows the effect of diffuser angle on pressure rise. An efficiency of 85 essentially says that the process is 85 close to true reversibility. However, recent work by Schmidt, which allows for a pressure on the annulus of the downstream-facing wall different from that at the upstream pipe outlet as well as other factors, gives good predictions.įor diffusers with annular two-phase flow, separation of the boundary layer has been inferred even at angles of 5° and depends on gas and liquid flow. Due to these forces, a pipeline bend can experience stresses along the bend that are called hydrodynamic stresses. Newtons second law states that a bodys momentum changes at the same rate as the net force upon it. Application of a separated flow model equivalent to that used for single-phase flow has been found to do poorly in predicting pressure change. Fluid flowing through a bend in a pipe changes direction, resulting in a change in momentum of the fluid. If the contraction is sharp or sudden, the behavior of single-phase flow is as shown in Figure 1 and involves a recirculation region. The length of the recirculation zone is similar to that for single-phase flow. Benefits are derived from the use of the piston cylinders since they can provide more efficient compression and expansion due to the closed nature of the. The flow of fluid through an enlargement (increase in pipe diameter) results in a decrease in velocity and consequently, a pressure rise. Because the flow is isentropic, it is also reversible (i.e. If the diffuser angle is > 45°, it can be taken as a sudden enlargement.ĭownstream of the step. Figure 15.8(c) shows a typical expansion over a continuous convex turn. During the compression process from 1 to 2, the compression piston moves toward the regenerator while the expansion piston remains stationary. The irreversible portion is determined by difference.įor a diffuser, methods which calculate growth of the Boundary Layer are required for example, those similar to Ghose and Kline (1978) which uses a momentum integral approach.
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