A special CAD/CAM software for electro-discharge machining of shrouded turbine blisks

In this paper, a special-purpose CAD/CAM software package, BliskCad/Cam, based on a commercial CAD/CAM software Unigraphics is developed to reduce difficulties in CNC-EDM of the shrouded turbine blisks. The software package consists of five modules such as electrode design, path searching, and machining simulation module. Functions of BliskCad/Cam include parametrical reconstruction of 3-D model of the blisk, intelligent design of complex shaped electrode, automatic generation of NC codes, search of interference-free tool path for multi-axis NC-EDM and machining simulation, etc. Experimental verification is conducted by using BliskCad/Cam and the results show that it satisfies the requirements, and can realize precision machining and reduce accessorial time remarkably.

Parametric Analysis and Design Considerations forMicroWind Turbines:A Comprehensive Review

Wind energy provides a sustainable solution to the ever-increasing demand for energy.Micro-wind turbines offer a promising solution for low-wind speed,decentralized power generation in urban and remote areas.Earlier researchers have explored the design,development,and performance analysis of a micro-wind turbine system tailored for small-scale renewable energy generation.Researchers have investigated various aspects such as aerodynamic considerations,structural integrity,efficiency optimization to ensure reliable and cost-effective operation,blade design,generator selection,and control strategies to enhance the overall performance of the system.The objective of this paper is to provide a comprehensive design and performance review of horizontal and vertical micro-wind turbines.The study begins with an overview of the current landscape of wind energy across the globe and India in particular,highlighting key challenges and opportunities.Numerical and experimental studies were used to validate the designs.Horizontal Axis Wind Turbines(HAWTs)with ducts or shrouds are suitable for microscale and low-speed applications.Researchers investigated the position and location of the turbines to enhance their performance in urban settings.Airflow and airfoil noise produce aerodynamic noise,which is the most significant disadvantage of wind turbines.The findings provide valuable insights for stakeholders interested in advancing micro-wind turbine technology.The highlighted research opportunities may be pursued further to improve the efficiency,reliability,and overall performance of micro-wind turbines.

Experimental Study on Impingement and Film Overall Cooling Characteristics of Turbine Shroud

Based on the variable characteristics of the actual operating conditions of the turbine shroud and the purpose of improving the cooling effect of the turbine shroud,this paper builds a test system of the impingement-film cooling shroud with two gas inlet angles(90°,167°).The effects of film cooling hole arrangement,gas inlet angle,blowing ratio(0.7,1.0,1.5,2.0,2.5,3.0)and temperature ratio(1.2,1.3,1.4,1.5,1.6)on the cooling characteristics of the impingement-film cooling shroud were experimentally studied by infrared temperature measurement technology,especially the effects of gas inlet angle and temperature ratio.The results showed that the film covering effect of the film cooling hole vertical or the same direction of the high-temperature gas incoming flow is better than the film covering effect of the reverse direction with the incoming flow,and the optimal arrangement of film cooling holes can improve the cooling effectiveness of the shroud.Compared with 90°intake gas,the film coverage area on the shroud surface of the 167°intake gas is expanded,and the surface average overall cooling effectiveness is increased by 1.03%to 12.6%.The overall cooling effectiveness of turbine shroud increases with the increase of blowing ratio,which increases the flow rate and pressure of cooling gas,and the corresponding increase rate is between 1.04%and 9.96%.However,the increase in the temperature ratio increases the mainstream heating capacity,resulting in a decrease in the cooling effectiveness of the shroud,with a maximum reduction rate of 11.04%.

Heat Transfer and Aerodynamics of Complex Shroud Leakage Flows in a Low-Pressure Turbine

A numerical investigation on over-shroud & inter-shroud leakage flow has been carried out to explore the underneath flow physics at the stage of shrouded Low Pressure(LP) turbine.Compared with the No inter-Shroud gap's Leakage flow Model(NSLM) and With inter-Shroud gap's Leakage flow Model(WSLM),the aerodynamic characteristics and the heat transfer performance have been studied.Through the aerodynamic point of view,it is concluded that due to the pressure difference between the rotor's passage and the over-shroud cavity,in the stream-wise direction,flow structure has been modified,and the inter-shroud leakage flow may even cause flow separation in the vicinity of the blade passage's throat.In the circumferential direction,separation flows appear over the rotor's shroud surface(upper platform of the shroud).Meanwhile,from the point of view of heat transfer,further provision on contour maps of the non-dimensional Nusselt number reveals that the reattachment of leakage flow would enhance the heat transfer rates and endanger the rotor's labyrinth fins over the shroud.However,due to the limited amount of inter-shroud leakage flow(current computational model),temperature distribution variation along the blade surface(near the rotor's tip section) seems to have only minor insignificant differences.At the end of the paper,the author puts forward some recommendations for the purpose of future successful turbine design.

Flow Regulation and Heat Transfer Characteristics in a Novel Turbine Shroud with Internal Asymmetric Throttle Chamber

Flow and heat transfer of a novel turbine shroud with throttle chamber under two kinds of orifice arrangements were numerically studied. The original shroud model composed of the impingement holes, film holes and jet channel. The two modified models have identical geometrical spacing except for the number and location of the orifices in the upper plate of the throttle chamber added in the jet channel. Different pressure values were set at the outlets of different row film holes simulating the mainstream favorable pressure gradient. The ratios of inlet total pressures of impingement holes to outlet static pressures of the third row film holes ranged from 1.6 to 3.6. The Nusselt number distributions were validated by the experimental data. The main target of this study was to quantify the impact of the throttle chamber on the flow regulation and internal heat transfer characteristics. The flow factor, relative mass flow rate, the Nusselt number and the heat transfer factors on the target walls were presented. It is found that the mass flow rate distributions in the film hole rows become more reasonable by the modification of location and number of the orifices on the throttle chamber. The throttle chamber decreases the heat transfer on the target walls.