Ge Xia

This study examines the cooling capacity of spiral-channel holes in the end wall using cascade wind tunnel experiments, and explores how the parameters of blowing ratio, film hole position, and compound angle affect the film cooling efficiency. The findings reveal that spiral-channel holes outperform cylindrical holes in cooling performance, primarily due to their ability to generate a more coherent cooling jet that extends over a broader surface area. Particularly, the cooling efficiency of the outlet and downstream regions of spiral-channel holes is found to be superior. When the mass flow ratio is 2.61% and 3.11%, the average efficiency of the case throughout the streamwise direction is 11.91% and 14.99% higher than that of the base, respectively. An examination of the mass flow ratio indicates that spiral-channel holes exhibit a higher initial value, which correlates with a significant improvement in film cooling performance at a critical mass-flow rate threshold of 2.33%. However, within the film cooling zone, the cooling efficiency decline is less severe compared to the unaffected areas as the temperature ratio rises. The study also notes that, when the expansion ratio increases, the overall cooling efficiency in regions influenced by film cooling declines further, with a more significant relative decrease observed at high Reynolds numbers. Additionally, as mainstream flow increases, the zone of high cooling efficiency at the outlet of film holes gradually diminishes. Notably, the zone of high cooling efficiency downstream of the fourth-row holes shifts from the pressure side toward the channel center, which, in turn, leads to a more evenly distributed cooling efficiency.

This study introduces a method for positioning film holes guided by conjugate isotherms. The aerodynamic performance exhibited by the turbine blade was evaluated, and the cooling effectiveness of various film hole configurations were systematically compared through combined numerical simulations and cascade wind tunnel experiments. Key influencing factors were investigated, and the underlying flow field structures and optimization mechanisms were elucidated. Numerical models reliably captured the aerodynamic and heat transfer characteristics, including pressure distribution and overall cooling effectiveness trends. Elevating the mass flow rate ratio was shown to enhance the overall cooling effectiveness across the blade surface. Modifications in film hole layout altered the cooling effectiveness along the blade region downstream of the holes and influenced cooling behavior in non-perforated areas near the endwall. While mid-blade cooling effectiveness showed minimal variation between Hole pattern #1 and #2, the latter exhibited superior overall cooling effectiveness at both the leading and trailing edges. Moreover, Hole pattern #2 diminished the temperature gradient between the suction and pressure sides, thereby augmenting blade structural integrity. Furthermore, Hole pattern #2 promoted a more even distribution of cooling effectiveness over the blade surface, leading to improved thermal protection. Therefore, strategic arrangement of film holes along conjugate isotherms serves as a vital approach for increasing gas turbine efficiency.

Thermal metamaterials are used in the design of thermal cloaks to achieve a series of functions, such as thermal invisibility and thermal concentration, representing a new approach for implementing energy transfer control in heat transfer processes. In this study, based on transformation thermodynamics, two functions, i.e., thermal rotation and thermal concentration, were set according to the time sequence and adopted the concept of spatial separation or space-sharing. Three cylindrical thermal rotary concentrators were designed by different spatial transformations. The numerical simulation results show that all three devices enable the concentration of heat flow in specific regions and alter the initial transfer direction of the heat flow. There is also no disturbance in the external heat flow transfer. These results effectively enrich the theory of transformation thermodynamics and provide different ideas for the subsequent study of thermal metamaterials.

Compressor blades are subjected to multiaxial loads during operation. Using uniaxial life prediction formulas to predict their fatigue life can result in significant errors. Therefore, by analyzing the loading conditions of the blades, a fatigue life prediction model suitable for compressor blades was developed. This model was established by applying the load of a specific engine type to a notched bar specimen and considering the gradient and strengthening effects. Firstly, the parameters of the SWT model were used as the damage parameters to determine the critical plane location based on the principle of coordinate transformation, and these results were compared with the actual fracture angles. Additionally, the physical mechanisms of multiaxial fatigue crack initiation and propagation were investigated at the microscopic level. Secondly, the non-uniform stress field on the critical plane was obtained using the finite element method. The stress distribution from the critical point to the specimen’s principal axis was extracted and normalized to calculate the equivalent stress gradient factor. Finally, the results of the comprehensive fatigue life prediction model were computed. Comparisons between the calculated results of the proposed model, the SWT model, and the Shang model with the experimental fatigue life showed that the prediction accuracy of the proposed model is higher than that of the SWT model and the Shang Deguang model.

Film cooling can continuously cover a layer of low-temperature gas film on the surface of hot-end components, thereby achieving the effect of isolating high-temperature gas, and can achieve a temperature drop of 600 K. As an advanced and efficient cooling technique, film cooling plays a crucial role in the process of turbine power and efficiency increase, with the key factor influencing its cooling performance being the configuration and arrangement of the film holes. This paper summarizes the design and arrangement of film hole configurations and discusses the potential directions for enhancing film cooling performance. Through analysis, the optimization of film cooling performance is mainly approached from two aspects: first, optimizing the hole configuration, which includes the study of shaped holes, enhancing the cooling performance of cylindrical holes using auxiliary structures, and forming a “reverse kidney-shaped vortex” structure by using a single combined film hole; second, optimizing the arrangement of the cooling holes on the turbine surface to achieve a more uniform and efficient distribution of the cooling film. Future development trends are primarily reflected in the following aspects: designing new, easily manufacturable, high-efficiency film hole configurations and further expanding their stable operating range is an important development direction. It is essential to validate the reverse heat transfer method, assess its applicable range, and, when experimental conditions exceed the applicable range, use related theories to correct its predictive performance. This is key to overcoming the bottleneck in film cooling prediction. It is critical to develop a film hole arrangement guideline that is suitable for various types of film holes and components with temperature differences at the thermal end, to fill the gap in future film cooling optimization design technologies. This study aims to provide new ideas for the optimal design of the cooling system and further improve the power and efficiency of gas turbines.

To address the dynamic and robust performance limitations of gas turbines in maritime autonomous surface ship applications, this paper proposes a novel nonsmooth fuzzy active disturbance rejection control (NS_FADRC) algorithm. This method combines the strengths of linear active disturbance rejection control (LADRC), nonsmooth control, and fuzzy adaptive control. First, the extended state observer (ESO) is improved by using the nonsmooth control method to enhance its convergence rate and estimation capability, while ensuring finite-time convergence characteristics. Next, fuzzy control logic is integrated to enhance the adaptability of the state error feedback (SEF), overcoming the limitations of traditional SEF in handling nonlinearities. The stability of the proposed control algorithm is further validated using Lyapunov stability analysis. Lastly, a Hardware-in-the-Loop (HIL) semi-physical simulation platform, based on automatic code generation technology, is developed to validate the algorithm’s performance. Experimental results demonstrate that, compared to the PID, FPID, and LADRC algorithms, the proposed NS_FADRC algorithm provides superior dynamic response during speed step tracking and excellent robust disturbance rejection performance in the presence of load disturbances, parameter uncertainties, and measurement noise.