Effect of three non-axisymmetric stator schemes on compressor performance with distorted inlet

In the boundary layer ingesting propulsion system, the compressor suffers from a non-uniform flow field. The compressor operating with distorted inflow continuously results in the loss of aerodynamic performance and stability margin. In this paper, three non-axisymmetric configurations are described for the stator of a transonic compressor to match the non-uniform flow field. The flow fields with distorted inflow at near stall condition are obtained and analyzed, the effects of the prototype stator and the three non-axisymmetric stators on aerodynamic performance are compared in detail. Results show that the non-axisymmetric stator schemes can effectively improve the stability margin of the transonic compressor and the maximum stability margin is relatively increased by 22.3% in all the three non-axisymmetric stators. The non-axisymmetric stator design is effective on decreasing the aerodynamic losses and improving the performance of the compressor operating with distorted inflow. Overall, the results show that in the design of the non-axisymmetric stator, the adoption of a curved-twisted blade and the increase of cascade solidity have the potential to reduce loss sources caused by distorted inflow.

Optimization of twisted blade of pump as turbine based on high dimensional surrogate model

In order to improve the operation efficiency of the twisted blade pump as turbine (PAT), a medium specific speed PAT was selected as the research object. The variables of the twisted blade plane blade profile were defined, the twisted blade was transformed into three plane blade profiles, and the blade profiles were parameterized by MATLAB 9.7 software. MATLAB 9.7, CFturbo 2020 and Fluent 19.2 were used to build the support vector machine-high dimensional model representation (SVM-HDMR) surrogate model function for efficiency optimization of PAT. Genetic algorithm was run on MATLAB 9.7 to optimize the surrogate model function, and the optimized blade profiles were fed back. The optimization results were verified by numerical simulation and experiment. The results show that the simulation efficiency of the PAT after optimization at the design operating point is 3.51% higher than the efficiency of the PAT before optimization, and the output power is increased by 5.3%. The test efficiency of the PAT after optimization at the design operating point is 3.4% higher than the efficiency of the PAT before optimization, and the output power is increased by 5.1%.

Research on design and numerical optimization of bowed-twisted-swept cascade of low aspect ratio hydraulic turbine

The bowed-twisted-swept modeling technology of three-dimensional blade has been widely used in the gas impeller machinery and achieved good results. This paper introduces the two-dimensional flow theory and the bowed-twisted-swept modeling ideology into hydraulic turbine design. Simultaneously combined with the popular NSGA-II multi-objective optimization algorithm, a complete set of hydraulic turbine cascade design method was proposed. Taking the last-stage low aspect ratio hydraulic cascade of Ф175 type turbine as an example, the parametric model of this cascade was reconstructed by a high-precision automatic bridge coordinate measuring machine. The multi-objective optimization design of three-dimensional modeling of cascade was completed with the single-stage turbine output torque, efficiency and pressure drop as the objective targets. Finally the influence of the bowed-twisted-swept modeling technology on the hydraulic turbine performance was explored in detail by a professional rotating machinery CFD software. Numerical analysis shows that the twisted blade design achieves a 1.5 times increase in torque and 2 to 4 times increase in pressure diff at same working condition. Moreover, when bowing optimization design and sweeping optimization design are applied on the twisted blade individually, the output torque and the stage efficiency of the hydraulic turbine are respectively improved, and when both two methods are simultaneously applied on the twisted blade, it is beneficial to reduce the pressure drop loss. However, it is noticeable that when the bowed-swept modeling technology used in a straight blade using almost have no effect on the turbine performance.

Experimental and Numerical Studies on the Influence of Blade Number in a Small Water Turbine

This paper demonstrates the procedure of blade adjustment in a Kaplan-type water turbine, based on calculations of the flow system. The geometrical adjustment of a twisted blade with varying chord length is described in the study. Computational fluid dynamics (CFD) analysis was used to characterise aerofoil and turbine performance. Furthermore, two turbines, with a different number of blades, were designed, manufactured, and tested experimentally. The numerical model results were then compared with the experimental data. The studies were carried out with different rotational velocities and different stator blade incidence angles. The paper shows a comparison of the turbine efficiencies that were assessed, using numerical and experimental methods, of a flow system with four- and five-bladed rotors. The numerical model results matched up well with those of the experimental study. The efficiency of the proposed turbines reached up to 72% and 84% for four-bladed and five-bladed designs, respectively. These efficiencies, when considered with the turbine’s simplicity, low production and maintenance costs, as well as their potential for harvesting energy from low energy flows, mean that Kaplan turbines provide a promising technology for processing renewable energy.

CFD for Helical Type Vertical Axis Wind Turbine

Vertical axis wind turbines are most effective for home energy generation especially in urban environments. Wind energy creates a stand-alone energy source that is relied on any place. The main criteria for this work is the design of micro wind turbines for all kinds of applications. Design of Twisted Blade Micro-Wind Turbine system is accomplished using computer aided design with Computational Fluid Dynamics (CFD). The flow characteristics in the wind turbine blade were analyzed by varying its twist ratio. The wind turbines with vertical axis utilize the wind from any direction with no yaw mechanism. The risk of blade ejection besides catching wind from all the directions is avoided by using the helical tye vertical axis wind turbine.