Intro to Cavitation in Chutes and Spillways

Registration Closed

The course is intended to give the participants an understanding of cavitation on chutes and spillways. The course will be introduced with a video of a case study that illustrates some of the fundamentals of cavitation and an explanation of why cavitation causes damage. Following the video, a Power Point presentation will discuss the beneficial effects of aeration on preventing damage due to cavitation. The participants will be guided to an Excel Spreadsheet program that reproduces all the Fortran programs given in EM 42. The Spreadsheet can be used to analyze chutes and spillways for their hydraulic and cavitation performance, to design aerators, to determine the best vertical alignment to minimize cavitation inception, and to analyze the cavitation damage potential of historic data.

Five Learning Objectives Of This Course:

A clear understanding of cavitation and how it is formedA clear understanding of the difference between cavitation and cavitation damage
Dam Failure Investigations and Forensic Reporting
The beneficial effects of aeration on preventing cavitation damage
The required surface tolerance to prevent damage with and without aeration
The availability of tools to study cavitation on chutes and spillways

Henry T. Falvey

Henry T. Falvey & Associates, Inc., Dr. Ing. Honorary Diplomate WRE

Henry T. Falvey has been president of Henry T. Falvey & Associates, Inc for 27 years. He retired from the USBR after 27 years with the Hydraulics Branch in the Research Division. He was the Senior Research Officer for 2 years with the Ecole Polytechnique Federale de Lausanne. He does both national and international consulting on the hydraulics of dams and has consulted or lectured on cavitation in 12 countries. He is the author of USBR Monograph 42, Cavitation in Chutes and Spillways, 1990. He is a lifetime member of ASCE and a member of both Sigma Xi and the International Association of Hydraulic Research. He has received awards from ASDSO, USSD, ASCE, and the USBR in recognition of his work pertaining to the hydraulics of dams and canals.

INTRODUCTION

Definition of boiling, gaseous cavitation, vaporous cavitation Armstrong Limit
Definition of Cavitation Index
Distinction between Cavitation and Cavitation Damage

BASIC CONCEPTS

Initiation of damage due to surface irregularities
Growth of calcite deposits in concrete
Bubble Collapse Mechanisms
Leap Frog Effect
Recognition of Cavitation Damage

MODEL TESTING

Physical Model
Reduced Pressure Chamber
Incipient Cavitation Characteristics of Specific Irregularities

FIELD OBSERVATIONS

Historical Extent of Damage
Damage Index

DAMAGE PREVENTION

Materials
Tolerances
Air Entrainment
AIR SLOT DESIGN
Placement
Types of Aerators

DESIGN TOOL

Computer Program
- Hydraulics Cavitation
- Characteristics
- Aerator Design
- Equal Cavitation Number Spillway
- Sinusoidal Cavitation Number Spillway