Valves of compressor

FSI Analysis of a Reciprocating Compressor

Reciprocating compressors use pistons driven by crankshafts to compress gases or liquids to high pressures. They are used abundantly in various industries (see Ref.).

During the operation of a compressor, the impact between the discharge valve and the stopper can generate significant noise (see Figure 1 and the movie above). To reduce this noise, it is necessary to study the internal mechanics of the compressor. Since the suction valve is very flexible, to be able to draw in large enough quantities of gases/liquids, there is strong coupling between the fluid flow and the structural deformations. Therefore, a fully coupled fluid-structure interaction analysis should be carried out.

In this News, we present some results of a fluid-structure interaction analysis of a compressor for a refrigerator. Figure 1 shows the geometry of the system established in I-DEAS and exported to ADINA. The different valves of the system are shown.

(a)


(b)

Figure 1  (a) Geometry of the CFD model; I-DEAS model (left), ADINA model (right)) (b) Suction valve, discharge valve and discharge valve stopper

In the model, the surfaces of the suction valve, discharge valve, and the discharge valve stopper are defined as FSI boundaries. The surface of the piston is defined as a moving wall. The other structural parts are defined as rigid bodies. The refrigerant is assumed to be a Navier-Stokes compressible fluid.

The movie at the top shows the von Mises stresses in the suction valve, discharge valve and discharge valve stopper. The large displacements of the suction valve and the impact between the discharge valve and stopper are worth noting.

The animation above shows a velocity vector plot in the compressor during its operation.

Figure 2 depicts the time history of displacements of the discharge valve, suction valve and discharge valve stopper.

Figure 3 presents the pressure inside the compressor as a function of volume, obtained using the ADINA FSI analysis and obtained by experiment. The results obtained with ADINA compare well with the experimental data.

Figure 2  Lifts of suction valve, discharge valve and discharge valve stopper; also, piston stroke and distance between suction valve and piston

Figure 3  Change of pressure as a function of volume; comparison between the ADINA FSI results and the experimental data

The above results of an FSI analysis and many others, see

ADINA Fluid-structure Interaction

illustrate the power of ADINA for use in industry and academia for such solutions.

Reference

• Wikipedia: Reciprocating compressor

Keywords:
Reciprocating compressor, refrigerator, valves, compressible Navier-Stokes, fluid-structure interaction, FSI, strongly coupled, I-DEAS data

Courtesy of ableMAX, Korea