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Hydroelectric power plants with the aim of being used to generate electrical energy are mostly operated in areas with sedimentation content which can cause wear and tear on the components of the hydropower plant. This activity is emphasized to determine the effect of quartz sand on the rate of abrasion on the guide vanes of the Francis type water turbine. This activity was carried out using a water turbine guide blade abrasion test tool with a guide blade test object made of SUS 304 stainless steel material. The results are presented quantitatively and qualitatively, the greater the concentration and diameter of the quartz sand particles, the water pressure and the angle given at the same time, the greater the rate of abrasion that occurs in the francis type water turbine guide vane. The highest abrasion rate was 5.10 (g/cm 2 x hour) in the angle variation test with a constant Q and a water: sand ratio of 70%: 30%.

To explore the impact of sediment-laden flow on the hydraulic loss in a turbine’s guide vane mechanism, this study conducts numerical simulations of sand-water two-phase flow in the full flow path of the Francis-99 turbine based on entropy generation theory, using the Mixture multiphase flow model and the SST k-ω turbulence model. Results show that hydraulic losses in the guide vanes are primarily governed by indirect dissipation (EPTD) and wall shear dissipation (EPWS), with direct dissipation (EPDD) caused by mean velocity accounting for less than 1%. These losses are mainly concentrated near the trailing edge of the guide vanes. The presence of sediment has a minimal effect on mean velocity, turbulence intensity, and entropy distribution, only slightly increasing wall shear entropy production. The findings provide technical references for anti-wear design and energy optimization in turbines operating in sediment-rich rivers.

Generally, industrial gas turbines (IGT) face transient behavior during start-up, load change, shutdown and variations in ambient conditions. These transient conditions shift engine thermal equilibrium from one steady state to another steady state. In turn, various aero-thermal and mechanical stresses are developed that are adverse for engine’s reliability, availability, and overall health. The transient behavior needs to be accurately predicted since it is highly related to low cycle fatigue and early failures, especially in the hot regions of the gas turbine. In the present paper, several critical aspects related to transient behavior and its modeling are reviewed and studied from the point of view of identifying potential research gaps within the context of fault detection and diagnostics (FDD) under dynamic conditions. Among the considered topics are, (i) general transient regimes and pertinent model formulation techniques, (ii) control mechanism for part-load operation, (iii) developing a database of variable geometry inlet guide vanes (VIGVs) and variable bleed valves (VBVs) schedules along with selection framework, and (iv) data compilation of shaft’s polar moment of inertia for different types of engine’s configurations. This comprehensive literature document, considering all the aspects of transient behavior and its associated modeling techniques will serve as an anchor point for the future researchers, gas turbine operators and design engineers for effective prognostics, FDD and predictive condition monitoring for variable geometry IGT.

Multi-stage pumps as turbines (PAT) are commonly employed in the petrochemical, coal chemical, and other process industries to recover liquid residual pressure energy. This study focused on improving the performance of multi-stage PAT, specifically targeting the slope of the power-flow(P-Q) curve and hydraulic efficiency at the rated flow point. A two-stage PAT was selected as the research object for this study. According to the relationship between the power and the geometrical parameters of the positive guide vane derived based on the basic equation of the multi-stage PAT, four parameters of the positive guide vane were selected as the test factors for the orthogonal experimental study. A four-factor, three-level orthogonal table of type L 9 (3 4 ) was established. Using Fluent software and the RNG k - ε turbulence model to carry out numerical calculations of constant flow, the results showed that: for the slope of the P-Q curve, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the outlet placement angle, the positive guide vanes number, and the base circle diameter; and for the hydraulic efficiency, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the positive guide vanes number, the outlet placement angle, and the base circle diameter of the positive guide vane. At the rated flow point, the P-Q curve of the optimized solution decreased by 0.24, resulting in a flatter curve and a 0.3% increase in hydraulic efficiency. There was little change in the vicinity at the rated flow point. The best efficiency point of the optimized scheme is biased toward the high flow rate, the efficiency is increased by 1.85%, and the best efficiency zone is wider. Therefore, selecting appropriate positive guide vane geometry parameters can flatten the P-Q curve, improve internal flow, and enhance hydraulic efficiency.

Guide vanes are the most eroded component of the Francis turbine, and flow instabilities around guide vanes influence the flow field at the runner inlet. Guide vane cascade can be considered an alternative method to investigate the flow field, which maintains flow similarity with the prototype turbine. The objective of this paper is to numerically analyze the flow field around the guide vane cascade. A single guide vane cascade numerical model is developed to perform the simulation using commercial software ANSYS 2022. Two turbulence models, shear stress transport k-ω and standard k-ε, perform steady-state simulation at the best efficiency point. The pressure and velocity distribution are obtained at mid-span, and around the pressure and suction sides of the guide vane. Numerical simulation on a scaled prototype full turbine has also been performed to measure the Francis turbine’s torque and efficiency. The modified Bhilangana- III guide vane profile is installed in the B-III hydropower plant in India and taken as a reference Francis turbine. The velocity and pressure distributions obtained around guide vanes of the scaled full turbine are compared with the velocity and pressure distributions of the single guide vane cascade. A difference of 7.25 % in maximum velocity and 9.40 % in maximum pressure at the mid-span of the guide vane is found between the guide vane cascade and scaled full turbine at the best efficiency point. The overall efficiency of the scaled turbine is also measured, and a difference of 0.83 % between the numerical result and scaled hill chart at the best efficiency point was found.

To investigate the impact of guide vane geometry—specifically, outlet angle, blade count, and radial height—on the performance of a Pump as Turbine (PAT), radial guide vanes were introduced upstream of the impeller in an IS80-50-315 low-specific-speed centrifugal PAT. Using an orthogonal test design, numerical simulations were conducted on 16 different PAT configurations, and the influence of vane geometry on performance was analyzed through a range analysis to determine the optimal parameter combinations. The results indicate that the number of guide vane blades significantly affects both the hydraulic efficiency and water head of the PAT under optimal operating conditions. Notably, the hydraulic efficiency of Configuration No. 1 (featuring five guide vane blades, a 6° outlet angle, and a 46 mm radial height) is 4.31% higher than that of Configuration No. 13 (with the same blade count but a 9° outlet angle and a 52 mm radial height). Additionally, Configuration No. 1 exhibits lower turbulence kinetic energy dissipation and reduced blade loading. Furthermore, the study reveals that a smaller guide vane outlet angle and reduced radial height contribute to improved operational stability.

Anti-guide vane is the component that converts energy and diversion flow in multistage centrifugal pump and its hydraulic loss is the main factor affecting pump performance. In this paper, the multistage centrifugal pump with radial guide vane is taken as the research object. Based on α 5 =35° inlet angle of prototype anti-guide vane, two optimization schemes of reducing and increasing the inlet angle are proposed to obtain α 5 ′ =25° and α 5 ′′ =45°. The SST turbulence model is used to simulate the centrifugal pump before and after optimization. The internal flow velocity characteristics, blade load distribution and pressure pulsation characteristics of the multistage centrifugal pump anti-guide vane were studied. The results show that under large flow conditions, the pump head and efficiency are increased by 4% and 2.66% respectively. And the flow loss in the anti-guide vane is reduced by 6.02%, which greatly improves the unstable flow caused by the impact separation at the anti-guide vane inlet. The blade load increases with the decrease of the anti-guide vane inlet angle, and the pressurization benefit of anti-guide vane is the largest when α 5 ′ =25°. The vibration amplitude of pressure pulsation is the largest at the anti-guide vane outlet, and the amplitude increases with the decrease of inlet angle. The research results can provide reference for the optimal design of the multistage centrifugal pumps anti-guide vane.

In composites, fiber–matrix thermal mismatch induces stress heterogeneity that is beyond the resolution of macroscopic approaches. The asymptotic expansion homogenization method is used to create a multi-scale thermo-mechanical coupling model that predicts the elastic modulus, thermal expansion coefficients, and thermal conductivity of ceramic matrix composites at both the macro- and micro-scales. These predictions are verified to be accurate with a maximum relative error of 9.7% between the measured and predicted values. The multi-scale analysis method is then used to guide the vane’s thermal stress analysis, and a macro–meso–micro multi-scale model is created. The thermal stress distribution and stress magnitudes of the guide vane under a transient high-temperature load are investigated. The results indicate that the temperature and thermal stress distributions of the guide vane under the homogenization and lamination theory models are rather comparable, and the locations of the maximum thermal stress are predicted to be reasonably close to one another. The homogenization model allows for the rapid and accurate prediction of the guide vane’s thermal stress distribution. When compared to the macro-scale stress values, the meso-scale predicted stress levels exhibit excellent accuracy, with an inaccuracy of 11.7%. Micro-scale studies reveal significant stress concentrations at the fiber–matrix interface, which is essential for the macro-scale fatigue and fracture behavior of the guide vane.

Centrifugal pumps play an important role in the national economy, they usually have complex flow fields and abundant flow structures. Based on the K-ε turbulence model and Zwart cavitation model, ANSYS was used to analyze the large guide vane centrifugal pump. Four schemes are proposed, each with 11, 13, 15, and 17 guide vanes respectively. When operating under different flow conditions, the external characteristics of the pump were analyzed and compared. The cavitation characteristics of the pump at the design flowrate and the pressure pulsation in the vaneless zone were analyzed. The influence of guide vane number on cavitation performance and pressure fluctuation in the vaneless region of the pump was studied. The final results show that the cavitation variation patterns of different schemes are similar. Z 0 =13 has the best cavitation performance, and Z 0 =17 has the worst cavitation performance. The change in guide vane numbers will affect the number of peaks and valleys at each monitoring point in the cycle, which correspond to guide vane numbers. Appropriately increasing guide vane numbers can reduce the amplitude of pressure fluctuation to a certain extent and reduce the pressure difference, which is beneficial for maintaining a stable state during unit operation.

To deeply investigate the internal flow characteristics of a Francis turbine under low-head conditions, this study takes a Francis turbine in a hydropower station as the research object. Based on the standard k-ω turbulence model, a full-flow passage numerical simulation was conducted to analyze the internal flow characteristics under different guide vane openings. The results show that at a 40% opening, the internal flow remains relatively stable, but the pressure gradient within the guide vanes undergoes the most significant variation, and the velocity vector distribution at the guide vane outlet is highly disordered. As the opening increases to 100%, a distinct low-pressure zone forms in the draft tube, exhibiting periodic variations over time. This leads to the generation of cavitation vortex ropes, which induce turbine vibrations and may significantly impact the normal operation of the hydroelectric generating unit.