Selection of a steam condensation model for atmospheric air transonic flow prediction

Wiśniewski, Piotr; Majkut, Mirosław; Dykas, Sławomir; Smołka, Krystian; Pritz, Balázs

doi:10.1016/j.applthermaleng.2021.117922

Cited by 26 publications

(8 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Molecular and macroscopic transport equations should not be ignored. The droplet growth equation in the free molecular state is given by the Hertz-Knudsen model [20], which is expressed as follows: is the condensation coefficient, which represents the number of vapour molecules on the droplet surface, indicates that vapour molecules are settling on the droplet surface, means that no vapour molecules are settling on the surface of the droplet. In the Hertz-Knudsen droplet growth model .…”

Section: Mathematical Modelmentioning

confidence: 99%

Performance prediction and loss evaluation of the carbon dioxide supersonic nozzle considering the non-equilibrium condensation

Guojie,

Yunpeng,

Jianming

et al. 2024

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

Carbon dioxide (CO2) is being considered as a promising working medium in energy conversion and refrigeration cycles due to its unique properties. When carbon dioxide flows with supersonic in turbo machinery (compressor), the non-equilibrium effect is enhanced due to the large change of fluid velocity, resulting in non-equilibrium condensation of the blade, which will seriously affect the performance of the compressor. Considering the similarities in flow characteristics between the nozzle and the compressor blade, the condensing flow of the blade can be predicted by simulating in a nozzle. The real gas model is used. The pressure and the nucleation rate are predicted based on the modified model, and the flow losses and thermal efficiency are analyzed in different states. The results show that the pressure variation in the nozzle aligns well with the experimental data. When the fluid transitions from subcritical to supercritical, the condensation interval decreases and the peak of the nucleation rate increases. The maximum supercooling decreases gradually. The flow losses are relatively large, and the thermal efficiency is low.

show abstract

Section: Mathematical Modelmentioning

confidence: 99%

Performance prediction and loss evaluation of the carbon dioxide supersonic nozzle considering the non-equilibrium condensation

Guojie,

Yunpeng,

Jianming

et al. 2024

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The nucleation process is based on the classical theory extended with the Kantrowitz correction, whereas the droplet growth model is based on the Knudsen number (Kn) [5]. Details about the condensation model implementation can be found in previous works of the authors [15,16,17,21,22]. This figure presents the structure of condensation and the aerodynamic waves arising in the expanding flow with a supersonic outlet.…”

Section: Numerical Studymentioning

confidence: 99%

“…An in-house code was developed by Dykas et al [8,9,10,11], who studied the condensation in nozzles with high expansion rate [12,13]. This code became the basis of the model implemented to commercial software ANSYS Fluent and is presented in this study [14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the moist air transonic flow in the symmetric and asymmetric nozzle of the low expansion

Wiśniewski

Dykas

Majkut

et al. 2022

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Condensation has a negative impact on turbomachinery efficiency in many energy processes. This paper compares the expansion of moist air in symmetric and asymmetric nozzles with a low expansion rate. The presented numerical study is supported by analytical and experimental research. The experimental tWesting was carried out using an in-house experimental test rig where two nozzles were examined for moist air with relative humidity of about 25%. The nozzles were tested for a supersonic outlet, as well as for the outlet condition with elevated pressure, which resulted in the occurrence of a normal shock in the test section. The asymmetric nozzle profile is congruent with the symmetric nozzle. However, the nozzle walls are shifted linearly in the flow direction. The Schlieren photography technique and static pressure measurements on the nozzle wall were used for qualitative identification of both condensation and shock waves. The presented numerical modelling was conducted using commercial computational fluid dynamics software extended with an in-house condensation model. The code was validated against in-house experiment as well as against the data available in the literature. The analysis of the flow in the considered two types of nozzles with a very low expansion rate revealed very interesting structures of pressure waves. The impact of the linear shift of the nozzle walls on the condensation process and the interaction of the condensation wave with aerodynamic oblique as well as normal shock waves were investigated.

show abstract

“…Wisniewski et al recommended a Hertz-Knudsen model for homogenous condensation in humid air. However, their single-fluid approach did not allow any analysis of spectrum statistics (Wiśniewski et al, 2022a). Moreover, they introduced a blending model, which applies a linear interpolation between the Hertz-Knudsen and the Fuchs-Sutugin models depending on the Knudsen number.…”

Section: Introductionmentioning

confidence: 99%

Modeling condensing flows of humid air in transonic nozzles

Hertwig

Wittmann

Wiśniewski

et al. 2023

Exp. Comput. Multiph. Flow

Self Cite

View full text Add to dashboard Cite

The ability to accurately model condensing flows is crucial for understanding such flows in many applications. Condensing flows of pure steam have been studied extensively in the past, and several droplet growth models have been derived. The rationale for the choice of growth models for condensation in humid air is less established. Furthermore, only a few validation cases for condensation in such flows exist. This paper aims to identify existing limitations of common droplet growth laws. The Hertz—Knudsen model is compared to heat-transfer-based models by Gyarmathy and Young, using an Euler—Lagrange approach in Ansys Fluent. For this, an adaption for Young’s growth law is introduced, allowing its application in condensation of different gas mixtures. The numerical model has been validated and applied to flows in nozzles and turbines in previous publications. The accuracy of the droplet growth models is investigated in transonic nozzle test cases. A case with pure steam and a case with humid air at two different humidity values are considered. Finally, the influence of humidity, Knudsen number, and droplet radius on the growth rate of each model is shown analytically. Flows at lower humidity values with longer condensation zones are shown to benefit from the higher sensitivity of the Hertz—Knudsen model to the mass fraction of water vapor in the flow. Heat-transfer-based models tend to overestimate condensation in such flows. However, the ability to empirically adapt the growth model by Young and its applicability in different Knudsen numbers results in good agreement with validation data over a wide range of cases.

show abstract

Selection of a steam condensation model for atmospheric air transonic flow prediction

Cited by 26 publications

References 35 publications

Performance prediction and loss evaluation of the carbon dioxide supersonic nozzle considering the non-equilibrium condensation

Performance prediction and loss evaluation of the carbon dioxide supersonic nozzle considering the non-equilibrium condensation

Analysis of the moist air transonic flow in the symmetric and asymmetric nozzle of the low expansion

Modeling condensing flows of humid air in transonic nozzles

Contact Info

Product

Resources

About