Analysis of swirl brake structural characteristics and construction of an axial thrust calculation method in the balance piston system of a turbopump

The balance of axial thrust is a critical technology for ensuring the safety, reliability, and reusability of turbopumps. Currently, the balance piston system is widely employed to achieve self-balancing of axial thrust. However, the influence characteristics of swirl brake structural parameters on the balance piston system have not been fully investigated, and existing axial thrust prediction methods still lack sufficient applicability. Therefore, following the validation of the numerical method using experimental test data, this paper conducts numerical simulations to analyze the influence mechanism of swirl brake structural parameters. It also investigates the distribution mechanism of fluid angular velocity and constructs a more effective integrated calculation model for axial thrust. The results show that the swirl brakes induce flow separation and reorganization by forming a wall-like structure at the initial position, resulting in a reduction in flow velocity of approximately 80%. Meanwhile, the system's through-flow capability is enhanced. The structural parameters of the swirl brake significantly affect the pressure distribution in the balance chamber, with variations reaching up to 12%, while the influence on axial thrust can be as high as 2%. Among the structural parameters, axial depth has the most significant effect on axial thrust. The influences of circumferential width and radial length are slightly less, while the effect of the number of swirl brakes accounts for approximately 25% of that of the other structural parameters. When the number of swirl brakes increases by two, the system's entropy generation decreases by approximately 9%. Additionally, the effect of circumferential width on entropy generation is also observed. In structural design, appropriately increasing the number of swirl brakes can help reduce flow losses. The predicted fluid rotation ratio k and pressure from the integrated calculation model show good agreement with the numerical results. Specifically, the deviation between the predicted pressure and experimental test data remains within 7%, and the deviation in the predicted axial thrust remains below 4%, confirming the applicability of the axial thrust integrated calculation model.