In the typical structure of a turboshaft aero-engine, the mass flow of the cooling air in the rotor-stator cavity is controlled by the inlet seal labyrinth. This study focused on the swirl flow and heat transfer characteristics in a rotor-stator cavity with considerations of the inlet seal thermal deformation effect. A numerical framework was established by integrating conjugate heat transfer (CHT) analysis and structural finite element method (FEM) analysis to clarify the two-way aero-thermo-elasto coupling interaction among elastic deformation, leakage flow, and heat transfer. Simulation results showed that the actual hot-running clearance was non-uniform along the axial direction due to the temperature gradient and inconsistent structural stiffness. Compared with the cold-built clearance (CC), the minimum tip clearance of the actual non-uniform hot-running clearance (ANHC) was reduced by 37–40%, which caused an increase of swirl ratio at the labyrinth outlet by 5.3–6.9%, a reduction of the Nusselt number by up to 69%. The nominal uniform hot-running clearance (NUHC) was defined as the average labyrinth tip clearance. The Nusselt number of the rotating disk under the ANHC was up to 81% smaller than that under the NUHC. Finally, a clearance compensation method was proposed to increase the coolant flow and decrease the metal temperature.

In advanced civil aero-engine, the gas exiting combustor typically features hot streak (HS) and swirl that affect the aerothermal performances of the high pressure (HP) nozzle guide vane (NGV). The purpose of this paper is to study the influences of HS on HP NGV aerothermal behaviors under swirl with various intensities. The numerical investigations were conducted on the first NGV of GE-E3 HP turbine. Four swirl intensities (|SN| = 0, 0.25, 0.50, 0.75) and two swirl orientations (positive and negative) were considered. The result indicates that the relative strengths between the swirl and its induced radial pressure gradient dominate the flow patterns on vane surfaces. Thus, the diverse streamlines distributions appear on the surfaces and the dominated factor on each surface does not vary with swirl intensity. The swirl redistributes the cold and hot fluid and thus generates the relatively hot oblique strip and cold region at the upstream of vane. The heat load on the vane that is not directly impinged by HS is dictated by the radial migration of the fluids originating from the regions aforementioned at |SN| = 0.25 and 0.50. However, at |SN| = 0.75, the transverse movement of HS due to the intense swirl causes additional thermal load. The heat load on the vane that faces HS is mainly determined by the radial migration of HS. The swirl alters the heat transfer distribution on vane surfaces remarkably. With positive swirl, the heat transfer coefficients at the lower span of suction side and pressure side are enhanced and weakened respectively. As expected, the opposite trends are observed in the negative swirl case. Swirl also affects boundary layer transition, and then affecting heat transfer. Positive and negative swirls both advance the transition on the suction side of vane directly impinged by the swirl, and with the increase of swirl intensity, transition onset shifts toward upstream.

The aero-engine pre-swirl system plays a critical role in cooling turbine rotor blades to maintain their temperature within operational limits. With advancements in propulsion efficiency and the reliable implementation of the secondary air system functions, such as blade cooling, rim sealing, and axial force control, modulated pre-swirl systems present significant potential applications for next-generation aero-engines. Adjustments to the pre-swirl system inevitably influence power consumption and cooling air temperature. This study develops an evaluation model for power consumption and temperature drop in the radial modulated pre-swirl system, incorporating all sources of power consumption and accounting for the coupled interactions between upstream and downstream flow and energy. The accuracy of the proposed model is validated through numerical simulations, and deviation sensitivity analysis is conducted to identify and assess potential sources of error. Furthermore, the proposed evaluation model is employed to analyze the effects of pre-swirl angle, rotational speed, and system pressure ratio on the flow characteristics and temperature drop of the radial modulated pre-swirl system. The results indicate that the model's predictions for system power consumption and swirl ratio distribution align closely with numerical simulations and published literatures, with maximum deviations of 7.2% and 18.9%, respectively, and a maximum temperature drop error of 2.03 K. Deviation sensitivity analysis reveals that the pre-swirl temperature drop and the outlet swirl ratio exhibit low sensitivity to errors in torque calculations, with maximum observed deviations of 1.9% and 5.3%, respectively.

This paper presents a numerical simulation of the flow structure of radial inflow between corotating disks with a negative ceff (effective inlet swirl ratio), which may occur in a vortex reducer equipped with deswirl nozzles. When the value of ceff approaches zero, asymmetric flow structure is observed in the cavity. Besides this, the flow structure inside the disk cavity at ceff < 0 can be divided into a source region, a sink region, an interior core region, and two Ekman layers, which is identical to the situation when 0 < ceff < 1. However, there exist two distinct patterns: the stagnation point on the disk and on the peripheral. According to a theoretical analysis, ceff = −1/8 is used to distinguish between these two patterns. Based on flow structure partitioning, a theoretical model for predicting the swirl ratio radial distribution and pressure drop in a disk cavity with ceff < 0 was established. The model employs the turbulent boundary layer integral method, and von Karman's assumption of velocity profile and wall shear stress for a free disk. The calculation results of the swirl ratio in the cavity are in good agreement with the computational fluid dynamics results except when the negative ceff approaches zero because of the deviation of the radial velocity profile from the “1/7” power law. Furthermore, pressure drop prediction across the cavity by the model has been verified through comparison with public experimental results.