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