DESIGN

Last Stage Tab

This tab is for selection and input of design conditions of last stage blade for Design Heat Balance.

The selection of "Condensing Flows" combo box of this tab is automatically reflected to the combo box with same name of "Start" tab.

Condensing Flows combo box

To select number of condensing flows(= exhaust flows) of reheat condensing turbine or LP turbine.

There are four selections, i.e. Single Flow, 2 Flows, 4 Flows and 6 Flows.

If Single Flow is selected, reheat turbine is assumed as single casing turbine, not separated into IP turbine and LP turbine.

Condensing Flows should be selected to have optimum annulus velocity(200 m/s ~ 300 m/s) at the last stage blade.   Before calculation, it is difficult to know the Condensing Flows having optimum annulus velocity.   ES_Rankine has a function to select automatically the Condensing Flows having optimum annulus velocity by automatic re-run after calculation.    When ES_Rankine pops up a warning message after calculation asking re-run for finding optimum annulus velocity, just click "OK" button to have ES_Rankine found optimum Condensing Flows as well as optimum last stage design from the reference Last Stage Design list.

 

Condensing Flow Total text box

To show total condensing flow calculated after run.   This is not for User input.

 

Condensing Flow Each text box

To show the flow of each condensing turbine exhaust calculated as condensing flow total divided by condensing flows.   This is not for User input.

 

Blade Length(BL) text box

To input the length of last stage blade, i.e. from blade roots to blade edge.   If User selects a reference design at Reference Design combo box, the blade length of the reference design is automatically filled into this text box.

 

Pitch Diameter text box

To input the Pitch Diameter of last stage blade, i.e. diameter of circle connecting the center line of blades..   If User selects a reference design at Reference Design combo box, the pitch diameter of the reference design is automatically filled into this text box.

 

Rotating Speed text box

To input rotating speed of last stage blade in rpm unit.

 

Annulus Velocity(Van) text box

To show annulus velocity of last stage calculated after run, according to the following equation.   This is not for User input.

Annulus Velocity, Van = Qa / An / RPM

wherein;

 

Qa

: Volume flow rate at turbine last stage exit

An

: Annulus area of turbine last stage

RPM

: Rotation speed of turbine last stage

 Annulus Area, An = 3.14 x PD x BL

wherein;

 

PD

: Pitch diameter

BL

: Blade length

 

Exhaust Loss text box

To show exhaust loss of last stage calculated after run.   This is not for User input.

 

Reference Design combo box

To select reference last stage design.   If clicked, blade length and pitch diameter of the reference design are automatically input into relevant text boxes.

 

Exhaust Loss Application frame

To select whether the exhaust loss shall be calculated by software automatically or by User input.

If Apply Constantly combo box is selected, User should input exhaust loss to be applied at Design Heat Balance as well as Design Annulus Velocity(Van).   Design Annulus Velocity shall be used as reference velocity to calculate exhaust loss at Operation Heat Balance from built-in standard exhaust loss curve.

 


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