-
are given in Table 1.
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Table 1 The dimension size in Fig.2 (m)
Inlet Stage 1 Stage 6 Stage 8 Stage 10 Outlet
S0 L1, D
L1, R S1
L6, D
L6, R
S6 L8, D
L8, R
S8 L10, D
L10, R
S10
Lout
0.0060 0.0040 0.0070 0.0069 0.0040 0.0050 0.0060 0.0029 0.0035 0.0075 0.0042 0.0038 0.0115 0.0055
In the dimensions in Table 1, we define S0 to
the channel is relatively small (only 0.0040 m in the prototype) as compared with the length of the flow
L6, R
as the “series passage”, where there is only a
passage, so the 2-D and single-precision solver is cho-
single way in and out, while after
L6, R , the flow is
sen. The implicit scheme of the segregated algorithm
pided into two parallel parts, which is defined as the
is adopted. Then the standard
k - turbulence model,
“parallel passage”, and it is shown that the narrowest in the “series passage” is 0.0040 m, while it is only 0.0025 m in the “parallel passage”. So it is very diffi- cult to mount the sensors to test the pressure and the velocity in the passage. Therefore, two alternative so- lutions might be adopted, one is the model experiment, which will scale and enlarge the prototype passage, and the other way is to use the CFD method for a nu- merical simulation. In the following sections, the model experiment results will be used to validate the CFD results and provide a series of simulation results to analyze the flow characteristics in the prototype labyrinth passage.
2. Validation of the numerical method
In order to validate the current numerical method, a model experiment is conducted by selecting a part of labyrinth passage just as shown in Fig.3. For the con- venience of mounting the pressure sensors, the passage is scaled to 4 times of the prototype, the inlet and the outlet are also shown in Fig.3.
Fig.3 A model passage used in experiment (scaled 4 times for the mounting pressure sensor conveniently)
There are total 7 YOKOGAWA EJA110A (0 kPa-500 kPa) pressure differential transmitters used in the experiment as shown in Fig.4(a). To avoid the severe vortex area and also to ensure the locations not far away from the pressure wave section, the pressure
the second-order upwind scheme, and the SIMPLE al-
gorithm are used for the solutions. Figure 4(b) shows the pressure contours of the selected model passage.
Fig.4(a) The pressure sampling points in the model passage
Fig.4(b) Pressure contours of model passage
Fig.4(c) The simulation vs. the experiment results at different points
Figure 4(c) depicts the simulation and experime- nt results for the static pressure at each sampling point, where p is the pressure of monitoring stations sele-