Meanwhile, the nozzle was optimized with the contraction–expansion structure based on the relationship between the Mach number and the nozzle’s cross-sectional area. The turbulent kinetic energy was optimized through a circular distribution of the nozzle to improve nozzle velocity uniformity, according to the effect of air flow on wall surface distance. With the purpose of solving the problems of uneven velocity and energy loss of the foreign fiber sorters, this paper has analyzed the nozzle distribution and structure in the foreign fiber sorting system, and presented the design of a nozzle with the circular distribution contraction–expansion structure. The experimental study of modified blades can be used to quantify numerical solutions. The results of the present numerical analysis were validated by the laboratory results of the reference blade.
As the amplitude of the wave increased, the amount of loss growing up, while the increase in wavelength caused the loss to decrease. The results show that in all three types of modified blades compared to the reference blade, the elimination of flow separation is observed and therefore the reduction of loss at the critical incidence angle of I = –15°. The mass flow average of loss at different incidence angles was calculated for the reference blade and modified ones for the sake of comparison. The distribution of the loss at different planes and mid-plane velocity vectors were shown. Models with appropriate and independent meshing have been simulated and studied by a commercial software. The selected numbers for the wave characteristics were based on the best results of previous studies. Three types of wave leading edges were designed with different wavelengths and amplitudes. This study aims to find a novel and inexpensive way to reduce loss with appropriate modifications on the leading edge of the turbine blade. Modifying the blade geometry, which might lead to the delay or elimination of the flow separation, can be considered as a passive flow control methodology. The blade profile and its geometrical features play an important role in the separation of the boundary layer on the blade. Simultaneous numerical tests are conducted to examine the interaction of different supersonic blade profiles with the partially injected flow to the rotor. Finally, the selected profile with superior performance is proposed. Moreover, the total pressure loss is 12% decreased for the selected model. It was found that the performance parameters such as efficiency, power and torque are increased by more than 8% in the selected best model, in comparison with the original model. Finally, the case with improved performance is introduced as the final optimum case. The numerical results are validated using the existing experimental results.
More than 10 types of two-dimensional blade profiles were designed using the developed preliminary design calculations and numerical analysis.
The turbine’s stator is a group of convergence–divergence nozzles that provide supersonic flow. As a result of its low mass flow rate, the turbine is used under partial-admission conditions. The studied model is a turbine with an output power below 1 MW and a large pressure ratio up to 20, which is used to gain relatively high specific work output. This paper aims to present the designing and investigating various types of impulse blade profiles to find the optimal profile that has better performance than the first or original blade.
0 kommentar(er)
