AS 6030 - Experimental Methods in Aero/Gas Dynamics

AS 6030 - Experimental Methods in Aero/Gas Dynamics

In-class Quizzes
Quiz Dates: Feb 13, Mar 20
Final exam: 24th Apr 2017
The quizzes will be Closed notes exams, for a duration of 15 minutes, towards the end of the 'E slot' class period.

Grading policy:

2 Quizzes (15+15 %)
One Project (30%)
Final examination (40 %)

Syllabus:

Flow visualisation Techniques

Particles in flow, Dye flow visualisation, Mie and Rayleigh Scattering,

Density gradient based techniques(Shadowgraph, Schlieren, Interferometry)

Other methods of visualisation

Various Flow test facilities

Low Speed wind tunnels

Blowdown / Continuous
open / closed circuit

High speed wind tunnels

Blowdown
Shock tube based facilities
Transonic tunnels

Low density flow facilities, Free flight facilities / Drop towers In-Space experiments

Measurement of Temperature

Physical state based

Dimension changes

Electrical property based

Radiation based

Spectroscopy based

Measurement of Pressure

Probes

Fluid column

Elastic sensing elements

Transducers (Piezo-electric, Piezo-Resistive)

Vacuum guages(McLeod Guages, Thermal conductivity, Thermocouple guages,Ionisation guages)

Measurement of Velocity

Pressure based (dynamic pressure related)

Hot wire Velocimetry

Flow visualisation based

Distance/time

LDV (only the basics)
PIV (Only basics)
PTV,LSV (only overview)

Measurement of Forces (If possible)

Measurement of Flowrates (If Possible)

References:

E.O. Doebelin
Measurement Systems: Application and Design
McGrawHill International edition, Mechanical engineering series, 4th ed. 1990.
R.J. Goldstein
Fluid Mechanics Measurements, Taylor&Francis, UK, 1996.
S.M. Gorlin and I.I. Slezinger
Wind tunnels and their instrumentation
Jerusalem Israel Program for Scientific Translations, 1966.
J. B. Barlow, W.H. Rae Jr., and A. Pope
Low speed wind tunnel testing
John Wiley & sons, 1999.
A. Pope and K.L. Goin
High speed wind tunnel testing
Kreiger Publishing co., 1978
G.S. Settles
SCHLIEREN AND SHADOWGRAPH TECHNIQUES: VISUALIZING PHENOMENA IN TRANSPARENT MEDIA
Springer-Verlag, 2001
C. Tropea, A.L. Yarin, and J.F. Foss (Eds.)
Springer Handbook of Experimental Fluid Mechanics
Springer Berlin Heidelberg, 2007.

Low speed flow visualisation:

The particle size,response time, scattered light(direction and intensity) if 'particle in flow'
Intensity of the light from the dye, concentration of the dye needed for visualisation if 'dye flow vis.'
'Light from scatterer(particle/dye) depends on light wavelength, particle size, and the collection angle
'Surface flow visualisation': Tuft vis., Oil film vis., clay/carbon black deposits
'Particles': Hydrogen bubble in water, smoke particles in air, condensates in air, dust in water, oil vapor in airglass beads in water/air.
High speed flow visualisation:

'Density variation in compressible flows': Shadowgraph, Schlieren, Interferometer
Shadowgraph: sensitive to second derivative in density, dark-bright fringe represents a shock, weaker gradients will give weaker changes in intensity, It is easiest to setup among the three techniques based on Gladstone-Dale relation
Schlieren: sensitive to first derivative of density, sensitive to derivatives that are at one plane in the test section (governed by lens formula) The signal is sensitive to the gradient perpendicular to the knife edge, The knife edge is placed to block part of the focal point of the uniform beam also.
Interferometer: Path lengths are same for both the beams, phases are different due to change in refractive index(or gas density) The fringes give density contours in the flow.
Low speed wind tunnels:

Non-dimensional parameters of concern to a problem
The flow happens due to pressure difference, the way the pressure differenece is given decides whether is is a continuous or intermittant facility.
Advantages and disadvantages of each of the candidate facility for a given experiment.
Starting of a supersonic wind tunnel, area ratios, critical pressures for the starting and for optimum running, how should one operate a supersonic facility designed for best power efficiency.
Low density facility
Low gravity facilities(aircraft in arc trajectory(centrifugal force opposing gravity), drop towers, space experiments
why do we need a diffuser, settling chamber, etc...
Application of any of the above knowledge to design a practical experiment