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Equilibrium and Non-Equilibrium Flows, Compressible Flows, and Choke Flows
Published in Robert E. Masterson, Nuclear Reactor Thermal Hydraulics, 2019
Many fluid properties required to calculate the behavior of choked flows (such as the stagnation enthalpy, the stagnation temperature, and the stagnation pressure) are based on conditions that exist when a fluid is brought to rest from a more energetic state. Normally, the stagnation enthalpy that is cited under these conditions (e.g., in Figure 29.10) is the enthalpy after the fluid is brought to rest adiabatically, that is, without heat being added or lost. To bring a flowing fluid into a stagnation state, any kinetic or potential energy it possesses must be used to increase its specific enthalpy, which can be thought of as its internal energy plus its flow energy:
Compressible Fluid Flow
Published in Raymond Mulley, Flow of Industrial Fluids—Theory and Equations, 2004
Energy transfer per unit mass between two points on a conduit is equal to the difference in stagnation enthalpy between these same two points when the flow is isothermal. The stagnation enthalpy is the sum of the enthalpy at flowing conditions and the kinetic energy change on bringing the fluid to rest adiabatically. A value for stagnation enthalpy can be computed even for processes that are not adiabatic since the concept is hypothetical.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
That is, in the absence of any heat and work interactions and any changes in potential energy, the stagnation enthalpy of a fluid remains constant during a steady-flow process. Flows through nozzles and diffusers usually satisfy these conditions, and any increase (or decrease) in fluid velocity in these devices will create an equivalent decrease (or increase) in the static enthalpy of the fluid.
Numerical analysis of the Sodium–Water Reaction in a minichannel to evaluate the safety of a Printed Circuit Steam Generator
Published in Journal of Nuclear Science and Technology, 2022
is the stagnation pressure, is the hydraulic diameter of the leak passage, and is the stagnation enthalpy of steam in . This correlation was comparable with the Moody’s model [36] under the saturated steam condition and used in the SELPSTA code that analyzed the system response of a SWR in the KALIMER to determine the steam leak rate [37]. The results of the leak rate calculated using the CFD and the correlation are summarized in Table 3. The CFD tends to underpredict the steam critical flow rate compared to the correlation. In the present CFD model, the ideal gas law determines the choking condition when the ratio of pressure in the crack to stagnation pressure becomes 0.53. Although it is recommended to use the real gas model or a property table of steam to predict the critical flow rate, the ideal gas law is used in this case to ensure the convergence of analysis.
One-dimensional Dynamic Model and Experimental Verification of Scramjet
Published in Combustion Science and Technology, 2021
Jianping Li, Guiqian Jiao, Wenyan Song, Zilong Liao, Kai Wang
where is the volume, is the total temperature of the outlet, is the gas constant of the outlet, is the constant volume-specific heat, is the fuel mass flow rate, is the fuel value, is the fuel combustion efficiency, is the fuel static enthalpy, is the total enthalpy of outlet flow, is the specific heat ratio of the outlet flow, is the inlet airflow rate, is the outlet airflow rate, is the stagnation enthalpy of the inlet airflow, and the stagnation enthalpy of the outlet airflow.
Optimization of a transonic axial-flow compressor under inlet total pressure distortion to enhance aerodynamic performance
Published in Engineering Applications of Computational Fluid Mechanics, 2020
Li Da, Lu Hanan, Yang Zhe, Pan Tianyu, Du Hai, Li Qiushi
To present the overall aerodynamic loss distributions for the flows in the tip clearance, the entropy creation is used because, unlike stagnation enthalpy, stagnation pressure and kinetic energy, its value will be independent of whether it’s obtained in the rotational frame or the stationary frame (Denton, 1993). The entropy distributions in the tip clearance at about 20% chordwise location are compared as described in Figure 15. For the baseline rotor, comparing the entropy distributions in the clearance at different circumferential locations, it can be found that more aerodynamic losses are suffered as the rotor blade is immersed in the distortion region (Figures 15(a) and (d)) than as the rotor blade is out of the distortion region (Figures 15(b) and (c)). Specifically, it is also noted that the most serious aerodynamic losses in clearance occur as the rotor is leaving the distortion region as shown in Figure 15(a). In the meanwhile, compared with the aerodynamic losses in clearance as the rotor is leaving the distortion region, less aerodynamic losses in clearance have been suffered as the rotor blade is entering the distortion region as shown in Figure 15(d). In the meanwhile, the rotor blade suffers from approximately the similar amount of aerodynamic losses in the clearance when it moves out of the distorted region as those when it moves towards the distorted region as depicted in Figures 15(b) and (c).