Post on 16-Dec-2015
Instructional Design Document
Shock Wave
STAM Interactive Solutions
Demo Outline (For reference)
Topic Number Topic Name Page Type
1 Nozzle Animated page
2 Internal Flow Pattern in a Nozzle Interactive page
3 External Flow Pattern Animated page
Slide 14Change the narration to: ‘As the approaching shock wave hits the wedge, it undergoes reflection and diffraction’
7
Changes Suggested by Prof. Puranik Changes reflected on slide no.
1 Start with definition of shock, voice over to say that internal andexternal shock will be discussed in this animation
Slide 4
2 Include shocks may be stationary as well. Slide 4
3 Show current (Nasa style) animation / interactivity for externalflow – add color to indicate temperature qualitatively. Replace“shock” with approaching flow, keep wedge stationary
Slide 13
4 Introduce parameters of convergent-divergent nozzles (shape,throat, P1 and P2Show images – flow velocity and location of shock
Slides 6-13
5 Add textbooks as suggested Slide 15
6 Modify quiz question 1 - Change language to say “across” the shock waveModify quiz question 2 -Correct answer is 1, not 2, Reframe as marked and show downstream/upstream on figure
Slides 16 & 17
Change Log (as per the minutes pdf)
Shock WaveFundamentals of Gas Dynamics
A shock wave is a disturbance that propagates through a medium. While the shock-wave usually travels through the medium, standing or stationary shock waves can occur in some circumstances in both liquids and gases.
Mach number describes the type of flow. This demo illustrates both internal and external flow patterns.
Shock WaveFundamentals of Gas Dynamics
Nozzle
Converging Diverging Nozzle
A nozzle is often used to control the speed of flow.
Shock WaveFundamentals of Gas Dynamics
Internal Flow Pattern in a Nozzle
Back Pressure (Pb):
Vary the back pressure to see the flow pattern.
Shock WaveFundamentals of Gas Dynamics
Reference slide for default value
The flow through the nozzle is completely subsonic.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is reduced by one step
The flow pattern is exactly the same as in subsonic flow, except that the flow speed at the throat has just reached Mach 1.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is further reduced by one step
A region of supersonic flow forms just downstream of the throat.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is further reduced by one step
The supersonic region extends all the way down the nozzle until the shock is sitting at the nozzle exit.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is further reduced by one step
Shock bends out into the jet, and a complex pattern of shocks and reflections is set up in the jet which will now involve a mixture of subsonic and supersonic flow, or just supersonic flow.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is further reduced by one step
Waves in the jet disappear altogether, and the jet will be uniformly supersonic.
Shock WaveFundamentals of Gas Dynamics
Reference slide if the back pressure is further reduced by one step
Expansion waves form at the nozzle exit.
Shock WaveFundamentals of Gas Dynamics
External Flow Pattern
Wedge (Object)
Approaching Shock Wave
Shock WaveFundamentals of Gas Dynamics
Resources
Books:
• J.D. Anderson, Modern Compressible Flow with Historical Perspective, 3rd Edition, McGraw-Hill, 2003.
• H.W. Liepmann and A. Roshko, Elements of Gas Dynamics, Dover Publications, 2001.
Reference Links:
• http://raphael.mit.edu/Java/
• http://en.wikipedia.org/wiki/Rankine-Hugoniot_equation
• http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060047586_2006228914.pdf
• http://www.efluids.com/efluids/gallery/gallery_pages/1supersonic_page.jsp
Shock WaveFundamentals of Gas Dynamics
The velocity, temperature and pressure across the shock wave are characterized by
Euler's Equation
Bernoulli's Equation
Navier-Stokes Equation
Rankine-Hugoniot Equation
Shock WaveFundamentals of Gas Dynamics
Downstream of the shock wave
Pressure and Temperature are lower
Pressure and Temperature are higher
Pressure is higher but Temperature is lower
Pressure is lower but Temperature is higherThis image will be enhanced
visually
Shock WaveFundamentals of Gas Dynamics
Which best describes the shock wave-front?
All thermodynamic properties of the medium change gradually
All thermodynamic properties of the medium change instantaneously
All thermodynamic properties of the medium change almost instantaneously
Some thermodynamic properties of the medium change gradually, some instantaneously
Shock WaveFundamentals of Gas Dynamics
The strength of a shock can be measured by the ratio of downstream to upstream pressures. As the Mach number increases
the strength of the shock wave decreases
the strength of the shock wave increases
depends on the medium of propagation
depends on the initial pressure in the medium
Shock WaveFundamentals of Gas Dynamics
Shock waves can be caused by
cavitations caused by the collapse of a bubble
objects such as bullets or planes flying faster than sound
explosions in gaseous media
objects such as bullets or planes flying at a speed less than sound