1. The upstream effect on back pressure ratio
Chunhui Li,
NIM, P. R. China

2. Background

3. The experimental system

4. Reynolds number effect
sonic nozzles
Orifice plate SN
throat diameter
flow
Reynolds number
apertures
[mm]
[m3/h]
[/]
8601
4.0250
8.80
5.25×104
18.218
8602
5.9090
19.20
7.76×104
8603
7.0020
26.90
9.14×104
8604
7.9820
35.30
1.05×105
30.708
8605
9.0855
45.30
1.19×105
8606
9.9360
54.50
1.31×105
8607
67.50
1.46×105
8608
85.00
1.64×105
8609
104.00
1.81×105

7. Type I-SN.8601

8. Type II-SN.8602

9. Geometrical effect Sonic nozzle Orifice plate SN Throat diameter [mm]
Diffuser angle
[°]
Reynolds number
apertures 01
10.021 6
1.34×105
30.708 02
10.020 4 03
10.018
2.5 04
5.006
6.69×104
18.218 05
5.038
6.74×104 06
5.010
6.70×104

11. 10mm-6。

12. Conclusions
The upstream condition or flow condition effect can be positive or negative, which may be related with the ration of the tube diameter to the throat diameter?
The measurement of CBPR on site may be necessary?

13. Discharge coefficient in transition region
How to relate the discharge coefficient and Reynolds number
during the transition region!