Effect of gas compressibility on fluid field of air‐cooled turbo‐generator

Abstract

Abstract The effect of gas compressibility on the fluid flow characteristics of a 350 MW air‐cooled turbo‐generator is investigated in this paper. Two gas models taking gas compressibility and incompressibility into account are established for numerical calculation. Then, a one‐fourth physical model based on the practical ventilation structure and basic assumption is built to analyse the flow velocity and flow rate using the finite volume method (FVM). The FVM‐predicted flow rate and flow velocity of cooling medium in the air cavity, stator and rotor of the generator show the distribution characteristics of flow rate and velocity in the generator is affected by the gas compressibility model selection. The comparison of FVM‐predicted flow rate and experimental value shows that the FVM‐predicted results using the gas compressibility model is more accurate when comparing to those using the incompressible model. Therefore, the gas compressibility model is an appealing approach to analyse the flow fluid characteristics of the air‐cooled turbo‐generator.

Keywords

• compressible gas
• finite volume method
• fluid field
• numerical calculation
• turbo‐generator