scholarly journals Computational fluid dynamics simulation of the supersonic steam ejector using different condensation model

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1655-1661 ◽  
Author(s):  
Lin Cai ◽  
Miao He ◽  
Ke-Zhen Huang ◽  
Wei Xiong
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Slip Velocity ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Entrainment Ratio ◽  
Maximum Value ◽  
Steam Ejector ◽  
Homogenous Nucleation ◽  
Condensation Model

This paper addresses the non-equilibrium condensation (NEC) in supersonic steam ejector under the assumptions of no slip velocity between the droplets and vapor phase and homogenous nucleation. The experimental data carried out by Moore has been used to verify the numerical results. It is illustrated that the maximum value of the flow mach number of the NEC model is lower than that of the equilibrium condensation model, and NEC model increases the ejector?s entrainment ratio in comparison equilibrium condesation model. When using the NEC model, the nucleation characteristics such as subcooling degree, nucleation rate could be obtained in ejector flow field.

Reduction of steady flow torques in a single-stage rotary servo valve

2018 ◽  
Vol 233 (4) ◽  
pp. 718-727
Author(s):  
He Wang ◽  
Long Quan ◽  
Jiahai Huang ◽  
Guofang Gong ◽  
Xu Yang
Keyword(s):  
Fluid Dynamics ◽  
Steady Flow ◽  
Geometry Optimization ◽  
Single Stage ◽  
Production Costs ◽  
Dynamics Simulation ◽  
External Diameter ◽  
Computational Fluid Dynamics Simulation ◽  
Servo Valve ◽  
Maximum Value

In this paper, geometry optimization of spool is proposed to reduce the steady flow torques in a single-stage rotary servo valve. The steady flow torques under different spool structures are studied by computational fluid dynamics simulation and experimental test and the most effective spool structure is found out. Then, the effects of geometry parameters on the steady flow torques are studied and an optimized solution for reduction of the steady flow torques is suggested by considering the optimization qualities and production costs. The results show that modification of the geometry of spool can make the jet angle at the orifices much closer to 90°, with almost no effect on the flow rate. Processing annular groove in the spool land with increased number of grooves on one side of the spool land is an effective way to reduce the steady flow torques. The maximum value of steady flow torques reduces with a gradual decrease in reduction as the external diameter of annular groove and the number of grooves increase. With the optimized spool structure, the maximum value of steady flow torques can be reduced significantly.

An Entropy Loss Approach for a Meanline Bladerow Model With Coupling to Test Data and 3D CFD Results

2005 ◽  
Author(s):  
John A. Reed ◽  
Mark G. Turner
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Dynamics Simulation ◽  
Flow State ◽  
Computational Fluid Dynamics Simulation ◽  
Entropy Loss ◽  
Cooling Flow ◽  
1D Model ◽  
N Stage ◽  
Loss Coefficients

A methodology which couples a computational fluid dynamics simulation and a ID meanline bladerow model employing entropy-based loss terms is presented. A 3D APNASA CFD flow solution of the GE90-94B was used to provide input to the 1D bladerow model, which computed entropy-generation terms from the flow state. These terms accounted for losses in mixing of leakage and cooling flow, and gross aerodynamics using bladerow entropy loss coefficients as defined by Denton. A description of the 1D model is presented. The 1D bladerow model was implemented in the NPSS system making it possible to easily construct N-stage component simulations. The 1D model was used to generate partial performance maps of the HPT and LPT for use in a coupled 0D-3D simulation of the full GE90 engine. To validate the approach, a data match of the GE EEE HPT at the design point has been made and presented. An extrapolation of the model to off-design points has compared favorably to the experimental data.

Computational fluid dynamics simulation of the supersonic steam ejector. Part 2. Optimal design of geometry and the effect of operating conditions on the ejector

2011 ◽  
Vol 226 (3) ◽  
pp. 715-723 ◽  
Author(s):  
L Cai ◽  
H T Zheng ◽  
Y J Li ◽  
Z M Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Optimal Design ◽  
Critical Pressure ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Working Fluid ◽  
Entrainment Ratio ◽  
Steam Ejector ◽  
Mixing Chamber

The aim of this study is to investigate the use of computational fluid dynamics in predicting the performance and optimal design of the geometry of a steam ejector used in a steam turbine. In the current part, the real gas model was considered using IAPWS IF97 model, and the influences of working fluid pressure and backpressure were investigated. The results illustrate that working critical pressure and backflow critical pressure exist in the flow. Moreover, the entrainment ratio reaches its peak at the working critical pressure. The performance of the ejector was nearly the same when the outlet pressure was lower than the critical backpressure. Effects of ejector geometries were also investigated. The distance between the primary nozzle and the mixing chamber was at optimum, the length of the mixing chamber and the diameter of the throat had an optimal value according to the entrainment ratio. When the length of the diffuser or throat was decreased within a range, the entrainment ratio did not change significantly.

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