Hostname: page-component-76fb5796d-wq484 Total loading time: 0 Render date: 2024-04-27T11:58:58.664Z Has data issue: false hasContentIssue false
  • English
  • Français

Design rules for small low speed wind tunnels

Published online by Cambridge University Press:  04 July 2016

R.D. Mehta  and
P. Bradshaw
R.D. Mehta
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
P. Bradshaw
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
Get access Rights & Permissions [Opens in a new window]

Extract

Even with today’s computers, a wind tunnel is an essential tool in engineering, both for model tests and basic research. Since the 1930s, when the strong effect of free-stream turbulence on shear layers became apparent, emphasis has been laid on wind tunnels with low levels of turbulence and unsteadiness. Consequently most high performance wind tunnels were designed as closed-circuit types (Fig. 1(a)) to ensure a controlled return flow. However, as will be seen below, it is possible with care to achieve high performance from an open-circuit tunnel, thus saving space and construction cost. ‘Blower’ tunnels (with the fan at entry to the tunnel, Fig. 1(b)) facilitate large changes in working section arrangements; to cope with the resulting large changes in operating conditions, a centrifugal fan is preferable to an axial one. For ease of changing working sections the exit diffuser is often omitted from small blower tunnels, at the cost of a power factor greater than unity. This paper concentrates on the design of small blower tunnels but most of the information is applicable to wind tunnels in general.

Type
Technical Notes
Information
The Aeronautical Journal , Volume 83 , Issue 827 , November 1979 , pp. 443 - 453
Copyright
Copyright © Royal Aeronautical Society 1979 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Houbolt, J. and Brooks, G. Differential equations of motion for combined flapwise bending, chordwise bending and torsion of twisted non-uniform rotor blades. NACA report 1346, 1958.Google Scholar
2. Carnegie, W. Vibration of pre-twisted cantilever blading allowing for rotary inertia and shear deflection. Journal of Mechanical Engineering Science Vol 6, No 22, pp 105–112, 1954.Google Scholar
3. Carnegie, W. and Thomas, J. The effects of shear deformation and rotary inertia on the lateral frequencies of cantilever beams in bending. Journal of Engineering for Industry, Transactions of the ASME, Vol 94, No 1, pp 267–278, 1972.Google Scholar
4. Dokumaci, E., Thomas, J. and Carnegie, W. Matrix displacement analysis of coupled bending—bending vibrations of pre-twisted beams. Journal of Mechanical Engi neering Science, Vol 9, No 4, pp 247–254, 1967.Google Scholar
5. Thomas, J. and Dokumaci, E. Simple finite elements for pre-twisted blading vibration. Aeronautical Quarterly, Vol 25, pp 109–118, May 1974.Google Scholar
6. Dokumaci, E. Pre-twisted beam elements based on approximation of displacements in fixed directions. Journal of Sound and Vibration, Vol 52, No 2, pp 277–282, 1977.Google Scholar
7. Abbas, B.A.H. Mechanical vibration and dynamic stability of complex structures by finite element method. Ph.D thesis, University of Surrey England, 1977.Google Scholar
8. Thomas, J. and Abbas, B.A.H. Finite element model for dynamic analysis of Timoshenko beam. Journal of Sound and Vibration, Vol 41, No 3, pp 291–299, 1975.Google Scholar
9. Abbas, B.A.H. and Thomas, J. The second frequency spectrum of Timoshenko beams. Journal of Sound and Vibration, Vol 51, No 1, pp 123–137, 1977.Google Scholar
10. Thomas, J. and Abbas, B.A.H. Dynamic stability of beams by finite element method. Journal of Engineering for Industry; Transactions of ASME, Vol 98, No 4, pp 1145–1151, 1976.Google Scholar
11. Abbas, B.A.H. and Thomas, J. Dynamic stability of fixed—fixed and free—free Timoshenko beams resting on an elastic foundation. Paper No 77—DET—134 an ASME publication.Google Scholar