Real Fluids

Author(s):  
Giovanni Carraro
Keyword(s):  
Author(s):  
Vineet Ahuja ◽  
Ashvin Hosangadi ◽  
Peter Cavallo ◽  
Jeremy Shipman

An innovative technique for simulating moving valve problems in liquid rocket testing facilities using cryogenic working fluids has been developed. This strategy uses a novel library grid approach in conjunction with an elasticity based grid movement solver with a multi-element unstructured CFD framework. The numerical formulation is based on a compressible gas-liquid framework that accurately models cavitation and multi-phase mixture acoustics while accounting for real fluids property variation. Demonstration of transient moving valve simulations for valve configurations operated at NASA SSC have been carried out for two different valves with very different plug operating profiles. The results are in good agreement with testing data for variable displacement plug motion as well as quasi-steady simulations for slow operating valves. Valve response to varying operating conditions such as plug speed can be predicted using the developed tool. This technique can also serve to analyze problems of valve stall, valve timing/scheduling and can reduce need for expensive activation runs at test facilities.


2015 ◽  
Vol 29 (13) ◽  
pp. 1550089 ◽  
Author(s):  
Minhui Shan ◽  
Jianxiang Tian

As is well-known, the structures and thermodynamic properties of fluids are determined by the complex interactions, i.e., the repulsive one and the attractive one, among particles. The simplest equation-of-state (EOS) model maybe the one of hard sphere repulsion plus or multiplying some attraction. Followed by the rapid promotion of the accuracy of hard sphere EOS in the past dozens of years, one question rises as whether more accurate hard sphere repulsion derives better prediction of the structures and properties of fluids with a special attraction. In this work, we used two repulsions with clearly different accuracy and some attractions to construct series equations of state (EOSs) for real fluids, and then we discussed the saturated properties at liquid–gas equilibrium. We found that the answer to the question aforementioned is not definitely standing.


Author(s):  
Nikola Stosic

Common use of screw compressors is in compression of air. However, application of screw compressors in refrigeration and air conditioning, as well as in process gas compression is increasing rapidly in recent years. The existing experimental data basis for air compressors may conveniently serve as a source for performance estimation of these compressors. A procedure was derived in this work to find scale factors which connect compressors operating with different fluids and it was applied for performance estimation of refrigeration and process gas screw compressors on the basis of measurements obtained for air compressors. Refprop 8 by NIST was used for calculation of thermodynamic properties of real fluids and ideal gas relation was used for air.


2012 ◽  
Vol 79 ◽  
pp. 153-162 ◽  
Author(s):  
Raquel V. Vaz ◽  
Ana L. Magalhães ◽  
Daniel L.A. Fernandes ◽  
Carlos M. Silva

2014 ◽  
Vol 88 ◽  
pp. 508-519 ◽  
Author(s):  
Tai-Wen Hsu ◽  
Jian-Feng Lin ◽  
Shih-Chun Hsiao ◽  
Shan-Hwei Ou ◽  
Alexander V. Babanin ◽  
...  

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