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Amilcar R Arvelo December 1, 1998 14:53

Which CFD software can solve this simulation accurately?

The schematic of the vortex generator is shown below. The generator consists of lower and upper chambers. The lower chamber has a central tangential inlet for refrigerant-rich solution (LiBr-H20, approximately 50%-50%). The heated refrigerant-rich solution enters the lower chamber tangentially and is accelerated as a consequence or the conservation of rotational momentum. With increased velocity, the pressure is reduced toward the central portion of the lower chamber. As a result, the heated refrigerant-rich solution gives up most of the refrigerant as vapor. The refrigerant vapor will flow out of the swirling mixture toward the center and upward. The vapor will then flow through the central outlet and out of the lower chamber into the upper chamber designed as a diffuser (with gradually increasing cross-sectional area). There the swirling vapor is tangentially decelerated as a result of rotational momentum and repressurized prior to leaving through the tangential outlet. The deceleration of flow in the upper chamber is essentially similar to what occurs in the diffuser of a compressor. The refrigerant-depleted solution in the lower chamber flows outward and is decelerated with some pressure recovery prior to flowing out of the lower chamber through the tangential outlet.

It is expected to convert at least 10% of refrigerant-rich solution (LiBr-H20, approximately 50%-50%) that enters tangentially to the chamber in vapor.

The problem in this situation is that we are working with two types of fluids. 1. Incompressible 2. Compressible

When the solution gets into the vortex chamber, it is incompressible. But once the refrigerant-rich solution is inside the chamber, a phase change occur due to pressure gradient. Now, we have a boundary that separates vapor (compressible) from the refrigerant-depleted solution (incompressible).

My question is: Which CFD software is capable to solve this simulation accurately ? Experts in CFD had told me that the Free Surface model will give me a good approximation of the results. But not accurate results.

andy December 1, 1998 16:55

Re: Which CFD software can solve this simulation accurately?
It looks like an interesting problem but a missing piece of information is Reynolds number (ie (a) low Reynolds number laminar, (b) low Reynolds number turbulent or (c) high Reynolds number turbulent). Another is the size of computer resouce available (ie PC or Cray) since you appear to have a lot of geometry. And another is what you mean by accurate.

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