Effect of Matching Parameters Between Rotor and Diffuser on the Flow Loss Characteristic in an Axial Turbine

2021 ◽  
Author(s):  
Xing Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Xuehui Zhang ◽  
Haisheng Chen
Keyword(s):  
Axial Turbine ◽  
Flow Loss ◽  
Loss Characteristic

Effect of Matching Parameters Between Rotor and Diffuser on the Flow Loss Characteristic in an Axial Turbine

2021 ◽  
Author(s):  
Xing Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Xuehui Zhang ◽  
Haisheng Chen
Keyword(s):  
Axial Turbine ◽  
Flow Loss ◽  
Loss Characteristic

Effect of Matching Parameters Between Rotor and Diffuser on the Flow Loss Characteristic in an Axial Turbine

2020 ◽  
Author(s):  
Xing Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Xuehui Zhang ◽  
Haisheng Chen
Keyword(s):  
Fluid Dynamic ◽  
Aerodynamic Performance ◽  
Expansion Ratio ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Turbine ◽  
Flow Loss ◽  
Loss Characteristic ◽  
Isentropic Efficiency

Abstract Diffuser is a key component affecting the aerodynamic performance of an axial turbine significantly. However, there is little research on the matching parameters between a rotor and a diffuser. In present study, effect of matching parameters which are normalized axial clearance (ACLR‘) and normalized radial size deviation (RDev‘) between rotor and diffuser on the aerodynamic performance and flow loss characteristic of a typical diffuser is revealed. A validated Computational Fluid Dynamic (CFD) model which couples the cavity between the rotor and diffuser is also proposed. The results illustrate that the isentropic efficiency is decreased with the increase of ACLR‘ and RDev‘. The RDev‘ presents a larger influence on isentropic efficiency. When ACLR‘ is increased from 0.21 to 0.43, the isentropic efficiency is only decreased by 0.3%, while the isentropic efficiency reduction of 0.65% is achieved when RDev‘ is increased from 0.091 to 0.192. A “leakage flow”, which is a result of the egress and ingress of the fluid near diffuser-cavity interface, is formed. It presents limited effect on the main flow in the diffuser when ACLR’ is only included and the flow loss near the guide cone surface is increased slightly. However, obvious back flow caused by the “leakage flow” is observed near the diffuser-cavity interface, when RDev’ is included. A flow separation is thus formed downstream and the flow loss in the diffuser is thus increased. The efficiency reduction caused by actual matching parameters (ACLR‘ with 0.21 and RDev‘ with 0.091) is increased with the decrease of expansion ratio. It can be more than 1.26% when the expansion ratio is less than 2.0. An isentropic efficiency reduction of 0.65% is found when different tip clearance are further adopted, and the mixture loss between tip leakage flow and back cavity flow can be neglected. In summary, matching parameters, especially for radial deviation, should be minimized reasonably in further optimization.

The Performance of a Low Speed One and a Half Stage Axial Turbine With Varying Rotor Tip Clearance and Tip Gap Geometry

1994 ◽  
Author(s):  
G. Morphis ◽  
J. P. Bindon
Keyword(s):  
Secondary Flows ◽  
Tip Clearance ◽  
Surprising Result ◽  
Loss Mechanism ◽  
Axial Turbine ◽  
Low Speed ◽  
Tip Leakage ◽  
Second Stage ◽  
Gap Flow ◽  
Flow Loss

The performance of a low speed axial turbine followed by a second stage nozzle is measured with particular reference to the understanding of tip clearance effects in a real machine and to possible benefits of streamlined low loss rotor tips. A radiused pressure edge was found to improve the performance of b single stage and of a one and a half stage turbine at the small tip clearance levels for which the radius was selected. This is in contrast to cascade results where mixing loss reduced the benefits of such tips. Clearance gap flow appears therefore to be just like other turbine flow where the loss mechanism of separation must be avoided. Loss formation within and downstream of a rotor are more complex than previously realized and do not obey the simple rules that have been used to design for minimum tip clearance loss. For example, approximately 48% of the tip leakage mass flow within a rotor appears to be a flat wall jet rather than a wrapped up vortex. The second stage nozzle efficiency was found to be significantly higher than for the first stage and to even increase with tip clearance. This is a surprising result since it means that not only is there a reduction in secondary flow loss but also that rotor leakage and rotor secondary flows do not generate downstream mixing loss.

The Control of Iron Bacterial Plugging of a Well by Tyndallization Using Hot Water Recycling

1986 ◽  
Vol 21 (1) ◽  
pp. 50-57 ◽  
Author(s):  
D. R. Cullimore ◽  
N. Mansuy
Keyword(s):  
Direct Injection ◽  
Small Diameter ◽  
Hot Water ◽  
Water Recycling ◽  
Water Heater ◽  
Time Intervals ◽  
Flow Rates ◽  
Water Well ◽  
Flow Loss ◽  
The Town

Abstract A small diameter water well drilled in 1977 in the Town of Bulyea, Saskatchewan generated such a rapid plugging (biofouling) that by 1979 the flow rate was reduced by 59%. Heavy growths of non-specific iron bacteria were found in the water and biofouling projected to be the principal cause of the flow loss. Tyndallization (repeated pasteurizations) treatment was applied using a hot water recycling system installed above the well head. Using a displacement passive gravity direct injection of hot water at 82°C from a water heater into the well, a sequential elevation of water column temperatures occurred until bio-film dispersion occurred (pasteurization) at 45°C+. A recovery to original flow specifications was repeatedly obtained at time intervals ranging from 6 to 403 days. Between treatments, a recurrence of biofouling was noted with flow reductions of 0.06 – 0.07 1/min/day frequently being noted. The rate of plugging appeared to be affected by the previous sequence of pasteurization treatments. Tyndallization was found to satisfactorily control iron bacterial biofouling and maintain flow rates.

scholarly journals New Equation for Predicting Pipe Friction Coefficients Using the Statistical Based Entropy Concepts

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 611
Author(s):  
Yeon-Woong Choe ◽  
Sang-Bo Sim ◽  
Yeon-Moon Choo
Keyword(s):  
Friction Coefficient ◽  
Accurate Determination ◽  
Mean Velocity ◽  
Friction Coefficients ◽  
Flow Discharge ◽  
Comparison Results ◽  
Flow Loss ◽  
Key Variables ◽  
New Equation

In general, this new equation is significant for designing and operating a pipeline to predict flow discharge. In order to predict the flow discharge, accurate determination of the flow loss due to pipe friction is very important. However, existing pipe friction coefficient equations have difficulties in obtaining key variables or those only applicable to pipes with specific conditions. Thus, this study develops a new equation for predicting pipe friction coefficients using statistically based entropy concepts, which are currently being used in various fields. The parameters in the proposed equation can be easily obtained and are easy to estimate. Existing formulas for calculating pipe friction coefficient requires the friction head loss and Reynolds number. Unlike existing formulas, the proposed equation only requires pipe specifications, entropy value and average velocity. The developed equation can predict the friction coefficient by using the well-known entropy, the mean velocity and the pipe specifications. The comparison results with the Nikuradse’s experimental data show that the R2 and RMSE values were 0.998 and 0.000366 in smooth pipe, and 0.979 to 0.994 or 0.000399 to 0.000436 in rough pipe, and the discrepancy ratio analysis results show that the accuracy of both results in smooth and rough pipes is very close to zero. The proposed equation will enable the easier estimation of flow rates.

Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance

2021 ◽  
pp. 095765092199394
Author(s):  
Hafiz M Hassan ◽  
Adeel Javed ◽  
Asif H Khoja ◽  
Majid Ali ◽  
Muhammad B Sajid
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Internal Flow ◽  
Large Temperature ◽  
Clear Understanding ◽  
Gas Temperature ◽  
Turbine Stage ◽  
Flow Angle ◽  
Axial Turbine ◽  
Stage Performance

A clear understanding of the flow characteristics in the older generation of industrial gas turbines operating with silo combustors is important for potential upgrades. Non-uniformities in the form of circumferential and radial variations in internal flow properties can have a significant impact on the gas turbine stage performance and durability. This paper presents a comprehensive study of the underlying internal flow features involved in the advent of non-uniformities from twin-silo combustors and their propagation through a single axial turbine stage of the Siemens v94.2 industrial gas turbine. Results indicate the formation of strong vortical structures alongside large temperature, pressure, velocity, and flow angle deviations that are mostly located in the top and bottom sections of the turbine stage caused by the excessive flow turning in the upstream tandem silo combustors. A favorable validation of the simulated exhaust gas temperature (EGT) profile is also achieved via comparison with the measured data. A drop in isentropic efficiency and power output equivalent to 2.28% points and 2.1 MW, respectively is observed at baseload compared to an ideal straight hot gas path reference case. Furthermore, the analysis of internal flow topography identifies the underperforming turbine blading due to the upstream non-uniformities. The findings not only have implications for the turbine aerothermodynamic design, but also the combustor layout from a repowering perspective.

Effect of chamber roughness and local smoothing on performance of a CAES axial turbine

2021 ◽  
Vol 170 ◽  
pp. 500-516
Author(s):  
Xing Wang ◽  
Xuehui Zhang ◽  
Zhitao Zuo ◽  
Yangli Zhu ◽  
Wen Li ◽  
...  
Keyword(s):  
Local Smoothing ◽  
Axial Turbine

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

2020 ◽  
pp. 095441002096645
Author(s):  
Jie Gao ◽  
Chunde Tao ◽  
Dongchen Huo ◽  
Guojie Wang
Keyword(s):  
Performance Improvement ◽  
High Efficiency ◽  
Three Dimensional ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axial Turbine ◽  
Flow Interactions ◽  
And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

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