Numerical Study of the Ejection Cooling Mechanism of Ventilation for a Marine Gas Turbine Enclosure

Abstract

A marine gas turbine enclosure must be designed to prevent overheating of the electrical and engine control components as well as diluting potential fuel leaks. In order to achieve an optimal enclosure design, a numerical study of the ventilation-ejection cooling mechanism of a gas turbine enclosure is carried out in this paper. The evaluation index of the ejection cooling performance is first proposed and the algorithm of numerical simulation is verified. On this basis, orthogonal combinations of structural parameters are carried out for the expansion angle α of the lobed nozzle and the spacing S between the outlet plane of the lobed nozzle and the inlet plane of the mixing tube. The flow and the temperature distribution inside the enclosure are analysed under different operating conditions. The results show that the influence of the lobed nozzle expansion angle α and the spacing S on the performance is not a single-valued function but the two influencing factors are mutually constrained and influenced by each other. For any spacing, the combined coefficient is optimal for the expansion angle α = 30°. When the expansion angle α = 45° and the spacing S = 100 mm, the combined coefficient and the temperature distribution inside the enclosure are optimal at the same time.

Optimization of exhaust ejector with lobed nozzle for marine gas turbine

“…As shown in Fig. 1, an exhaust ejector with a lobed nozzle ejector in the gas turbine enclosure is investigated in this study [28]. Since the exhaust plenum outlet is square, a square-to-circle transition section is needed to connect the two parts of the exhaust plenum outlet and the lobed nozzle, and the same is true for the connection between the mixing tube and the gas turbine enclosure.…”

“…The ejecting cooling system's aerodynamic characteristics are investigated using an ideal gas as the fluid medium. Considering the accuracy of the Realizable k-ε model in simulating round hole jet flows, this numerical simulation employs the Realizable k-ε turbulence model [28]. The strength of FLUENT in simulating turbulent lies in its provision of a multitude of advanced turbulence models and solution algorithms, coupled with its powerful parallel computing capabilities, which together ensure the precision and efficiency of the simulations.…”

“…Each part is set to a slip-free wall with an emissivity of 0.9 [28]. The temperature of each part is defined in sections according to the state of gas turbine operation, and the specific temperature settings are shown in Table 2.…”

“…In summary, the ejector of the engine casing has become a widely studied subject for scholars both domestically and internationally, involving multiple aspects of investigation. Scholars have conducted indepth research on the ejection mechanism of casing ejectors and made significant efforts in optimizing the lobed structure [28]. However, there are still some unresolved issues.…”

Untitled

“…where P1 represents total pressure at the inlet of the ejector device and P2 represents total pressure at the outlet of the ejector device. q represents the dynamic pressure at the inlet of the ejector device [24].…”