Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Results Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers about results output using Bentley PULS Item #1: My question was regarding the valve fluttering as seen in the PV card and flow rate calculations not matching the Ariel performance program. I updated the pressure units. Before I was entering psig and now I have updated all my pressure inputs to psia. This seems to alleviate some of the problems I was having regarding the PV card valve chatter. But the flow rates don't match the Ariel performance program. Answer: Flow rates calculated by PULS assume 100% efficiency. Usually PULS flow rates are higher by about 10% or so. Furthermore, Ariel diagram does not account for pressure pulsation on piping side since it does not have that information. PULS adds pulsation at the valve node to show its effect on compressor performance. The more pulsations the more power loss and PULS computes this loss and displays that in the output report. Item #2: I was not able to see a graph of the pulse shape at a flow velocity node (with an external file used for input) Answer: There is a problem with external file input format. The file should not be saved a txt file, but as (*.* All files) Item #3: it seems that the software is very frequency analysis oriented, but I want to see time signals of the pulsation Answer: Program is based on frequency solution. You can see time signals for reciprocating boundary conditions. Item #4: How do you get the report for eigen frequency in the dynamic analysis in order to check the eigen frequency of the piping system. Answer: The report for eigen frequencies is the "frequency report". The word eigen refer to resonance or natural frequency. It is a mathematical term. In addition, as mentioned in the PULS Manual Tutorial and training manuals here and here : Mechanical and Acoustic oscillations are considered uncoupled. That is AutoPIPE type vibrations do not cause more gas or liquid oscillations. The two analysis are done separately. For example, shaking forces from PULS are entered into AutoPIPE to calculate mechanical vibrations. Constant (i.e. frequency independent) piston and pressure sources can be used to generate acoustic mode shapes The source amplitude is arbitrary in this case. In order to compute acoustic resonances and mode shapes, only one source is needed. PULS does not output the resonance frequencies but will show you the system response. The animated peak responses represent the acoustic mode shapes of the system. See Also Bentley PULS Bentley AutoPIPE External Links Bentley Technical Support KnowledgeBase Bentley LEARN Server Comments or Corrections? Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to the "Comments" area below. THANK YOU!
↧