Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels
Abstract
:1. Introduction
2. Model Building
2.1. Mechanism of Wetness Losses
2.2. Governing Equations
3. Numerical Method
4. Physical Model Description
4.1. Validation
4.2. Physical Model and Experimental Method
5. Results and Discussion
5.1. Effect of the Location of Suction Surface (D point) on Condensation Flow
5.2. Effect of the Location of Pressure Surface (C Point) on Condensation Flow
5.3. Effect of Parallel Channel Width on Condensate Flow
5.4. Performance Comparison of Modified Cases
6. Conclusions
- (1)
- The location of the suction surface (D point) can significantly affect the distribution of steam nucleation rate and Mach number. The closer the D point is to the trailing edge of the cascade, the more prominently the steam nucleation is delayed, the smaller the average wetness at the cascade outlet is, and the better the dehumidification performance of the cascade is.
- (2)
- The location of the pressure surface (C point) has little effect on the distribution of steam nucleation rate and Mach number. The location of C point causes no significant difference in the average wetness of cascade outlet, indicating that it has little effect on cascade dehumidification performance.
- (3)
- It is necessary to choose suitable widths for parallel channels. A small parallel channel width corresponds to weak condensation shock intensity and poor dehumidification characteristics, while a large parallel channel width is associated with strong condensation shock intensity and better dehumidification characteristics. Considering the comprehensive performance of the cascade, it is suggested that the parallel channel width should be between 3 and 5 mm.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
δhx | wetness loss |
xm | mean dry degree |
Δhi | effective enthalpy drop (kJ·kg–1) |
e | energy density, (kJ·kg–1·m–3) |
FD | viscous resistance (N) |
ht | total enthalpy (kJ·kg–1) |
hfg | condensation latent heat (kJ·kg–1) |
J | nucleation rate (m3·s)–1 |
k | Boltzmann constant |
Kn | Knudsen number |
m | single molecular mass (kg) |
mass generation rate (kg·s–1) | |
Ma | Mach number |
N | amount of droplets (m–3) |
p | pressure (Pa) |
Prg | Prandtl number |
qc | condensation coefficient |
r | droplet radius (m) |
rc | critical droplet radius (m) |
R | gas constant (J·(kg·K)–1) |
S | supersaturation ratio |
TS | saturation temperature |
γ | gas adiabatic constant |
φ(P) | correction coefficient of droplet growth model |
T | temperature (K) |
ΔT | degree of supercooling (K) |
u | velocity component (m·s–1) |
Y | wetness |
σ | liquid surface tension (N·m–1) |
λg | thermal conductivity of gas (W·(m·K)–1) |
δ | semi-empirical correction coefficient |
ρ | density (kg·m–3) |
Subscript | |
g | gas |
d | liquid |
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Case Number | Average Wetness of Cascade Outlet (%) | Wetness Losses (kJ/kg) | Total Pressure Loss Coefficient |
---|---|---|---|
ORI | 2.65 | 1.45 | 0.073 |
0.57-0.69-5 | 2.59 | 1.41 | 0.087 |
0.57-0.72-5 | 2.62 | 1.43 | 0.083 |
0.57-0.76-5 | 2.54 | 1.36 | 0.094 |
0.57-0.79-5 | 2.33 | 1.18 | 0.113 |
Case Number | Average Wetness of Cascade Outlet (%) | Wetness Losses (kJ/kg) | Total Pressure Loss Coefficient |
---|---|---|---|
ORI | 2.65 | 1.45 | 0.073 |
0.45-0.79-5 | 2.40 | 1.24 | 0.104 |
0.57-0.79-5 | 2.33 | 1.18 | 0.113 |
0.68-0.79-5 | 2.42 | 1.26 | 0.114 |
0.77-0.79-5 | 2.37 | 1.22 | 0.119 |
Case Number | Average Wetness of Cascade Outlet (%) | Wetness Losses (kJ/kg) | Total Pressure Loss Coefficient |
---|---|---|---|
ORI | 2.65 | 1.45 | 0.073 |
0.57-0.79-1 | 2.60 | 1.40 | 0.082 |
0.57-0.79-3 | 2.53 | 1.35 | 0.094 |
0.57-0.79-5 | 2.33 | 1.18 | 0.113 |
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Han, Z.; Zeng, W.; Han, X.; Xiang, P. Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels. Energies 2018, 11, 2306. https://doi.org/10.3390/en11092306
Han Z, Zeng W, Han X, Xiang P. Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels. Energies. 2018; 11(9):2306. https://doi.org/10.3390/en11092306
Chicago/Turabian StyleHan, Zhonghe, Wei Zeng, Xu Han, and Peng Xiang. 2018. "Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels" Energies 11, no. 9: 2306. https://doi.org/10.3390/en11092306