Effect of multi-zone effusion cooling on an adiabatic flat plate for gas turbine application

The present study performed a three-dimensional numerical analysis on an adiabatic flat plate with forward injection holes for multi-zone film cooling. The cooling holes were divided into three-zone, and the cold air was supplied from cylindrical holes at a velocity ratio of 0.5 and 1.5 with 30° inclination to the primary flow. The effect of multi-zone arrangement in film cooling effectiveness is studied, and a comparison between two-zone and three-zone arrangement has been made. Results show that the three-zone arrangement helps achieve better film cooling effectiveness than the two-zone arrangement due to the uniform flow of coolant at a higher velocity ratio. It also reduces the mass flow rate of secondary flow by decreasing the number of cylindrical holes in the perforated plate.

Study on the Expansion of Primary Flow for the Mixing Uniformity in the Two-Phase Ejector

The expansion of primary flow in the suction chamber of the CO2 two-phase ejector is investigated and its influences on the mixing characteristics are analyzed. An ejector model is developed, by constructing differential equations for mass, momentum and energy then get the governing equation. In the suction chamber, the expansion of primary flow and the compression of secondary flow are modeled along the flow path. Based on the constant-pressure mixing theory, the pressure equilibrium positions of two stream (namely at the inlet and inside of mixing chamber, respectively) are considered. The mass and energy transfer in the mixing chamber were analyzed by using the double-flow model formulation. The ejector performance parameters are obtained for the different operation conditions, and the distributions of temperature and velocity of two streams in the mixing chamber are presented. The simulation results showed the influence of primary flow expansion on the pressure lift ratio was relatively obvious, and the larger expansion distance was helpful to improve the mixing efficiency and decrease the thermodynamic entropy change during the mixing. Moreover, the temperature of secondary flow for lower primary flow pressure presented larger descent rates at the initial of mixing. This work is helpful for the improvement of ejector theoretical model and the optimization design.

Study on the proportion and flow path of Yangtze River water diversion into Taihu Lake

The purpose of this study is to quantify the proportion and flow path of the water diversion from Yangtze River (YRD) into Taihu Lake. Based on the analysis of rainfall and data of Taihu basin in recent 30 years, a 1-D hydrodynamic model of main inflow river network area of Taihu basin was constructed, coupled the convection-diffusion model with conservative material, the characteristics of YRD and the water inflow into Taihu Lake (WITL) in three typical years were calculated. The results show that the YRD has shown a significant upward trend in the past 30 years, accounting for 26.4, 35.6 and 42% of the total WITL in three typical years of wet, normal and dry respectively. From the perspective of space, Taige River is the largest river in the western part of the lake that is affected by the river diversion (35%–72%), and Wuxi River is the smallest (1–3%). In addition, the primary flow path of YRD to Taihu Lake was through the Wuyi River and Lake Gehu from the water diversion station west of the Zao River.

Effects of Shock Wave Phenomenon on Different Convergent Lengths in the Mixing Chamber of the Steam Ejector

The shock wave phenomenon is a phenomenon in a steam ejector that caused when the working fluid has high pressure, and suddenly it turns into low pressure and high speed. The shock wave effect will be investigated to the different convergent length in the mixing chamber to find the highest entrainment ratio as the performance of steam ejector. Operating pressure in the primary flow was in the range 0.68 MPa - 1.39 MPa, and the secondary flow was set 0.38 MPa to 0.65 MPa. The result of this study demonstrated that the highest entrainment ratio occurred in the convergent length of 69 mm.

Details of Shrouded Stator Hub Cavity Flow in a Multi-Stage Axial Compressor Part 1: Interactions With the Primary Flow

The flow in shrouded stator cavities can be quite complex with axial, radial, and circumferential variations. As the leakage flow recirculates and is re-injected into the main flow path upstream of the stator, it deteriorates the near-hub flow field and, thus, degrades the overall aerodynamic performance of the compressor. In addition, the windage heating in the cavity can raise thermal-mechanical concerns. Fully understanding the details of the shrouded-hub cavity flow in a multi-stage environment can enable better hub cavity designs. Since the majority of the open literature presents limited details about the structure of compressor cavity flows in the stator wells and how the cavity wells affect the leakage flow, there is a lack of wholistic knowledge of how these flow parameters are interdependent. To shed light on this topic, a coupled CFD model with inclusion of the stator cavity wells for the Purdue 3-Stage (P3S) Axial Compressor Research Facility using the PAX100 configuration was developed and validated against experimental data. Such a model not only quantifies the impact of cavity leakage flow on compressor performance, but it also provides the capability to investigate the flow structure details including the path of the fluid into and out of the cavity. With the model in place, in this part 1 paper, the influence of the hub leakage flow on compressor performance and its interactions with the primary flow were investigated by varying the clearance ratio of a single stator. The understanding of the primary-hub-leakage flow interactions can offer insights leading to better designs of hub cavities.

Variasi Diameter Nozzle Terhadap Lamanya Proses Vakum Pada Fresh Water Generator di Laboratorium Polimarin

Ejector is a static pump which is worked by a vacuum principal. A vacuum which is happened in the ejector affect the performance and the ability of suction on the secondary mass flow section. A vacuum ejector in the fresh water generator affects the amount of fresh water which is generated. The objective of this research is to know the affection of variation in the outlet diameter of the nozzle towards secondary mass flow, especially on the air suction section (vacuum). In this research, an analysis has been done in a fresh water generator (FWG) with three alternative design of the outlet diameter of the nozzle using Computer Fluid Dynamics (CFD) method to get the optimal performance. The inlet pressure of primary flow is regulated to be steady at 3 bars. The variations of the diameter outlet of the nozzle are 4, 6, and 8 mm. The distance between the edge of the nozzle with outlet flow of the pipe is made at a settled position. The edge of the nozzle is at 3 mm inside the outlet flow of the pipe measured from the inside edge of the pipe. The result of CFD method is shown that on the variation of the outlet diameter of the nozzle 8 mm has the biggest mass flow (4.6838048 kg/s) between 4 and 6 mm. The implication of this research is that the outlet diameter of the nozzle 8 mm has the maximum value of a vacuum.

Application Based Performance Analysis of a Priority Flow Divider Valve Using Power Hydraulic Systems

Priority flow divider valve (PFDV) splits the flow in two different paths: Primary flow path and Secondary flow path. It can be used in twice applications: a system needs to perform dual functions against dual loads simultaneously and to obtain a stable flow by supplying a compensated flow from secondary flow line to the primary flow line using an energy storage device and a control valve. Two different hydraulic systems are identified to analyze the steady and dynamic performance of the PFDV. The first hydraulic system with PFDV is designed for automobile steering system with a load sensing control strategy in the presence of multiple actuators whereas second system is designed for wind turbine hydraulic power transmission to obtain stable power from it in the absence of generator. Both power hydraulic systems are modeled using bond graph technique and simulated in SYMBOLS SHAKTI software to analyze the PFDV performance.

Experimental investigation on mixing characteristics of high speed co-flow jets by using tabbed chevron nozzle

The present study investigates the effect of chevron with tab (Tabbed chevron) fixed at the exit of the co-flowing primary nozzle on the mixing characteristics in subsonic and sonic jets. The experiment was conducted for the jet Mach number 0.6 and 0.8. The centerline Mach number decay was calculated for all these jet Mach numbers for the co-flow baseline nozzle, nozzle with chevrons and tabbed chevron (primary flow) nozzle respectively. It was found that tabbed chevron was effective in reducing the potential core length by 88.23% as compared to the chevron nozzle with baseline nozzle. The radial profile also shows that the mixing enhancement by tabbed chevron is better than chevron nozzle.