Experiment No:
4
Date: Calibration of Supersonic Wind Tunnel
21/08/2018
To carry out calibration of Supersonic Wind Tunnel and to observe the pressure,
Aim temperature, density distribution along the nozzle isentropic flow from stagnation point to
entrance of test section
- To validate the working condition of given CD nozzle before testing any model
- To understand the pressure, temperature, density, velocity and Mach number
Why this
variation across the nozzle
Experiment?
- To understand the amount of stress acting on various places of the test section
- To verify the Mach number at test section
- Mach 2 Convergent Divergent Nozzle
Apparatus - Supersonic Tunnel
Required - Pressure Scanner
- Data acquisition system
𝛾
𝑃0 𝛾−1 2 𝛾 𝑃0 𝜌0 𝛾 𝑇0 𝛾−1
Formula used =(1+ 𝑀 )𝛾−1 & ( )= ( ) = ( )
𝑃 2 𝑃 𝜌 𝑇
Reading Static Area of
s from Pressur cross
Densit 𝐴 A/A
the e Section
𝑃 y (Kg/ T M 𝐴∗
Pressur ( in Bar) P/Po (mm2) M
𝑃0 m3) (K) *
e
Scanner
(in psi)
6.7 58.423 4.0253 1.000 4.6289 303 000 9000 1.760 0.31
9.2 3.7950 0.9428 4.4381 298 0.29 6460 1.231 0.57
Location of static pressure
55.08
Ports in C-D Nozzle (cm)
10.4 47.387 3.2650 0.6111 3.9810 235 0.56 5280 1.006 0.90
10.9 27.471 1.8928 0.4702 2.7002 244 1.10 5248 1.000 1.00
- from front end
Table required 11.4 22.15 1.5262 0.3791 2.3154 230 1.26 5344 1.018 1.16
12 22.47 1.5482 0.3946 2.3394 231 1.27 5472 1.043 1.23
13.9 21.142 1.4567 0.3619 2.2396 227 1.30 6124 1.167 1.49
16.7 16.126 1.1111 0.2766 1.8457 210 1.46 7234 1.378 1.74
20.7 13.031 0.8978 0.2230 1.5851 197 1.64 8300 1.582 1.92
26.8 11.497 0.7921 0.1968 1.4494 190 1.72 9148 1.743 2.04
34.9 7.668 0.5283 0.1312 1.0853 170 1.98 9428 1.796 2.07
45.2 7.438 0.5123 0.1273 1.0619 180 2.01 9524 1.815 2.05
Note:
1. Pressure value corresponding to position “6.7” can be considered as stagnation point
2. Stagnation temperature is assumed to be 303 K
3. “10.9” refers throat location, “45.2” refers the inlet of test section
Diagram / Photo Yes - Diagram of CD nozzle with pressure port location
required
- Procedure
1. Firmly fix the Mach 2 CD nozzle inside test section of supersonic wind
tunnel
2. Run the compressor until reservoir filled with enough air pressure (ex: 100 psi)
3. Close the side doors of test section with proper lock systems.
4. Connect the pressure ports of CD nozzle with respective pressure scanner ports.
5. Switch on the pressure scanner with USB drive connected (as procedure mentioned in
Procedure
the Lab manual)
6. Open both the pressure valve of supersonic wind tunnel simultaneously so that to
create favorable pressure gradient between inlet and exit of CD nozzle
7. Keep the pressure valve in open condition until reservoir pressure reach zero.
8. Switch off pressure scanner
9. Take out the reading from the USB drive using software ‘Pressure Scanner V 1.1’.
𝑃
1) 𝑃0
Vs X (Distance in (mm))
2) Static Pressure (in Bar) Vs X (Distance in (mm)
3) Density (Kg/m3) Vs X (Distance in (mm)
Graph Required 4) Temperature Vs X (Distance in (mm)
5) Mach Number (M) Vs X (Distance in (mm)
𝑃 𝐴
6) Mach number calculated from 𝑃 Vs Mach number calculated from 𝐴∗
0
(Tip: Use Matlab or Excel to plot the above graphs)
Measure the area ratio of given Mach No-2 for C-D Nozzle.Find the Mach No at different
Conclusion
Area location using gas table with experimental data.
Measure the area ratio of given M=2 C-D Nozzle. Find the Mach number at different
Activity
area location using Gas tables and compare with experimental data.
1. High-Speed Wind Tunnel Testing “Alan Pope, Kenneth L. Goin” Krieger Pub Co
Further Readings 2. Gas Dynamics “ Ethirajan Rathakrishnan” PHI Learning Private Limited-New Delhi
3. Modern compressible flow “J.D.Anderson” Tata McGraw Hill
