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Products  |  Fluid Mechanics  |  Steady Flow of Compressible Fluids  |  HM 261
HM 261 Nozzle Pressure Distribution Show data sheet (pdf file) Print page
Technical Description

  Convergent nozzles are used in the subsonic range. Velocities in the supersonic range can be achieved in de Laval nozzles; their nozzle geometry is a combination of convergent and divergent contours. De Laval nozzles are used in supersonic wind tunnels, steam turbines, jet engines and rocket technology. Pressure curves are a good way of representing the different velocity ranges in the nozzle, such as subsonic, supersonic and shock wave.
  The experimental unit HM 261 is used to measure pressure curves in convergent and convergent-divergent nozzles (de Laval nozzles) and to study the actual flow of compressible fluids. In addition, the "choking effect" is demonstrated, where the mass flow stops increasing upon reaching the critical pressure ratio. Air is used as a compressible fluid.
  In the experiment, the air flows through a nozzle and is thus accelerated. The pressure curve is recorded in the direction of flow over several measuring points. The air pressure upstream and downstream of the nozzle can be adjusted.
  Three interchangeable nozzles are available to study the pressure and velocity ratios: one convergent contour and two de Laval nozzles with different length nozzle extensions.
  The measured values for temperatures, pressures and mass flow are recorded.
  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.  

Learning Objectives / Experiments

- pressure curve in de Laval nozzles
  * convergent nozzles
- connection between entry pressure and mass flow

  or exit pressure and mass flow
- how pressure drop in the nozzle affects the

- determining the critical pressure ratio (Laval

  pressure ratio)
- demonstration of the "choking effect"
- proof of shock waves


* Pressure distribution in convergent and

  divergent nozzles1
* Three nozzles with different contours1
* Speed of sound and shock wave

Alternative products
HM 230 -- Flow of Compressible Fluids
HM 260 -- Characteristics of Nozzles

[1] nozzle pressure distribution in actual flow of compressible fluids
[2] three nozzles with pressure measurement points: 1 convergent nozzle, 1 short and 1 long de Laval nozzle
[3] compressed air regulator for adjusting the pressure downstream of the nozzle
[4] needle valve on the flow meter for adjusting the back pressure
[5] instruments: manometer and digital temperature display upstream and downstream of the nozzle as well as rotameter


Technical Data

 Air consumption of the experimental unit
- compressed air: max. 10bar
- air consumption: approx. 5g/s
3 nozzles, brass
- 1 x de Laval nozzle, short nozzle extension
- 1 x de Laval nozzle, long nozzle extension
- 1 x convergent nozzle
Compressed air regulator
- control range: 0...8,6bar

Measuring ranges
- temperature: 0...100C
- pressure: 2x 0...10bar, 8x 1...9bar
- mass flow: 0,7...8,3g/s

Dimensions and Weight
LxWxH: 750x450x830mm
Weight: approx. 41kg
Required for Operation
230V, 50/60Hz, 1 phase or 120V, 60Hz/CSA, 1 phase
Compressed air connection max. 10bar, 250NL/min
Scope of Delivery
1 experimental unit
3 nozzles
1 set of instructional material
Order Details
070.26100  HM261  Nozzle Pressure Distribution
© 2005 G.U.N.T. Gerätebau GmbH