„Supercavitation“

A new Aeration Technology

Prof. Dr.-Ing. Schmid A.

8th International Symposium on Cavitation - CAV2012 Singapore

Cavitation induced by hydrodynamic processes

Flow direction

Pressure distributioninside a

cavitation-nozzle

Cavitation induction inside a nozzle

Low energy input High energy input

Pumpcharacteristic

Pressure P

Flow

-rat

e Q

Pulsed cavitation

Supercavitation

Mixed cavitation

Startingcavitation

Bernoulli-limitof cavitation

Flow region without cavitation

0 barabsolute pressure

Limit ofpressure loss

Characteristics of cavitation nozzle

Demonstration of „Supercavitation“

„Supercavitation“-bubble development

Source: University of Minnesota – Twin Cities - USSt. Anthony Falls Laboratory - http://cav.safl.umn.edu/gallery.htm

„Supercavitation“ - sheath

Air-injection pipe

Cavitation nozzle

"Supercavitation"

Air

Aerator principle

Mechanical Aerator – Cav-Jet

1

2 3

4

ROTOX 1

ROTOX 2Cav-Jet

Inlet

Outlet

Experimental setup at WWTP Regnitzlosau

Operational data from WWTP Regnitzlosau

0

500

1000

1500

2000

2500

0

100

200

300

400

500

Pure oxygen consumption [m 3̂/d] Electricity consumption [kWh/d]

20.0

8.20

01

05.0

3.20

02

Pure oxygen consumption [m^3/d]

Ele

ctri

city

con

sum

pti

on

[kW

h/d

]

ContinuousTesting

Test start

0

500

1000

1500

2000

2500

Oxygen consumption [m^3/d]01.1

0.20

02

20.0

4.20

03

Oxygen consumption [m^3/d]

Test phase of Cav-Jet

Icing problems

Operational data from WWTP Regnitzlosau

Oxygen input at treatment plant

Time

Dis

solv

ed o

xyge

n co

ncen

trat

ion

Rotox-Aerator

Cavitation-Aerator

Two-film theory of oxygen transfer – diffusion controlled

Water associates at low temperature

D1

D2

Supercavitation by tangential flow

Thank you very much for your attention

Literature

Schmid A.: New Jet-Aeration System using "Supercavitation" Environmental Science & Pollution Research, 17, 3, 582 - 585, 2010.

Schmid A., Geier W.: Vorrichtung und Verfahren zum Einbringen von gasförmigem und/oder flüssigem Medium in Flüssigmedium. Deutsche Patentschrift DE 103 20 840, 2003.

Schmid A.: Vorrichtung und Verfahren zum Einbringen von gasförmigem und/oder flüssigem Medium in Flüssigmedium. Deutsche Patentschrift DE 10 2004 027 398, 2004.

Flow characteristics