in centrifugal pumps what impeller type and what each impeller describe?

There are three types of impeller configuration:

1- Open Type Impeller (nothing but vanes distributed equally around the central hub) 

2- Semi-Open Impeller (distributed vanes around central hub with just one covered side and the other is opened)

3- Closed Type Impeller (distributed vanes around central hub with both sides covered)

1-open impeller consists of  nothing but     vanes attach to central hub 

2-open impeller 

3-closed impeller