Identification of Coupled Natural Frequencies in a Rotor-Stator Test-Rig for Different Gas Properties

Barabas, B.; Brillert, Dieter; Dohmen, Hans Josef; Benra, Friedrich-Karl

doi:10.29008/etc2017-057

Cited by 3 publications

(4 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A rotor-stator cavity test rig with carbon dioxide was designed and built-up to investigate the cavity flow at the University of Duisburg-Essen. A sketch of the main region is shown in Figure 3 [1]. The main parameters of the test zone are listed in Table 1, which describes exactly the geometry of the back chamber of the original Duisburg rig [1].…”

Section: Rotor-stator Cavity Test Rigmentioning

confidence: 99%

“…A sketch of the main region is shown in Figure 3 [1]. The main parameters of the test zone are listed in Table 1, which describes exactly the geometry of the back chamber of the original Duisburg rig [1]. The front chamber (FC) is the test section.…”

Section: Rotor-stator Cavity Test Rigmentioning

confidence: 99%

“…The maximum value of y + in the two simulation models is 3.4. The SST k − Ω turbulence model in combination with the scalable wall functions is selected [1]. The values of C w and Re investigated in this paper are given in Table 4.…”

Section: Numerical Simulation Set-upsmentioning

confidence: 99%

“…The main application fields of centrifugal carbon dioxide compressors are at oil exploitation sites as the supplies of injection gas or at carbon capture and storage power plants for carbon dioxide compression [1]. To transport more fluid and to lower the energy consumption, the rotational speed of the impeller in a large centrifugal carbon dioxide compressor increases rapidly, whose circumferential Reynolds number Re, defined in Equation (1), is up to 2.09 × 10 7 . There are two main methods used to improve the compressor efficiencies.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Numerical Investigation of Flow and Heat Transfer in a Rotor-Stator Cavity with Centripetal Carbon Dioxide Through-Flow

Fu³

et al. 2019

Energies

View full text Add to dashboard Cite

A centrifugal carbon dioxide compressor is a kind of general machine with extensive applications. The geometry of the side chambers of the compressors can be determined by studying the rotor-stator cavity with centripetal through-flow. In this paper, numerical simulations were conducted to predict the characteristics of flow and heat transfer. Three different speeds of rotation and two axial gap widths were considered. The correlations of the core swirl ratios were determined by fitting the results for two axial gap widths. The amounts of the moment coefficients of the disk were predicted. In order to better analyze the temperature field, the radial distributions of the local heat transfer coefficient were numerically investigated. According to the simulation results, the average Nusselt number was found to be dominated by the turbulent flow parameter. It also seemed to be proportional to the moment coefficient at a fixed circumferential Reynolds number.

show abstract

Section: Rotor-stator Cavity Test Rigmentioning

confidence: 99%

Section: Rotor-stator Cavity Test Rigmentioning

confidence: 99%

Section: Numerical Simulation Set-upsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Numerical Investigation of Flow and Heat Transfer in a Rotor-Stator Cavity with Centripetal Carbon Dioxide Through-Flow

Fu³

et al. 2019

Energies

View full text Add to dashboard Cite

show abstract

Generalized Model for the Approximation of Coupled Acousto-Mechanical Natural Frequencies in High-Pressure Centrifugal Compressors

Heinrich

Kühhorn

Steff

et al. 2020

Volume 11: Structures and Dynamics: Structural Mechanics, Vibration, and Damping; Supercritical CO2

View full text Add to dashboard Cite

The oil and gas, chemical, and process industries employ centrifugal compressors for a wide range of applications. Due to this, the conditions under which centrifugal compressors have to operate, vary significantly from case to case. Gas pipeline compressors, for example, may feature discharge pressures well over 100 bar. In other fields of application, like gas injection, which is used to enhance oil recovery, this quantity can reach considerably higher values. Here, discharge pressures over 600 bar and gas densities over 300 kg/m3 are not uncommon. During the last several decades, comprehensive research was conducted on the impact of high pressure operating conditions on the vibrational behavior of centrifugal compressor wheels. Nowadays, it is well-known that an increase in gas pressure levels leads to a more pronounced interaction between the side cavities and the impeller, which results in a frequency shift of the acoustic and structural modes. For the safe operation of compressors, it is necessary to predict these coupled natural frequencies accurately. The state-of-the-art approach to achieve this objective is the finite element method. While this technique provides high-quality results, the simulation of acousto-mechanical systems is still a time-consuming process that incurs high computational costs. Therefore, finite element models are, in this case, not suitable for probabilistic studies, sensitivity analyses, and comprehensive simulations of the full operating range of the compressor. In 2013, Magara proposed a simplified model based on an annular plate between two cylindrical cavities to solve this problem. While this method reduces the required computational effort significantly, its use is limited to platelike impellers. The authors of the current paper propose a more generalized method to overcome the challenges mentioned above. It uses the uncoupled structural and acoustic modes of the actual impeller and side cavities in a modal superposition to approximate the natural frequencies of the coupled acousto-mechanical system. In this way, the intended design geometries of the impeller and side cavities are considered while maintaining the advantages of Magara’s model regarding the computational effort. In a numerical study, Magara’s method and the generalized model are applied to different systems of increasing complexity. The investigation starts with a simple annular plate in a cylindrical cavity and ends with an actual compressor impeller. At every complexity level, the results of both approaches are compared to a finite element analysis. Moreover, measurement data of a simplified rotor in a cylindrical cavity is used to validate the numerical models. Finally, the paper concludes with a discussion of the limitations and benefits of all employed numerical methods.

show abstract

Acoustoelastic Modes in Rotor-Cavity Systems: An Overview on Frequency Shift Effects Supported with Measurements

Unglaube

Brillert

2022

IJTPP

View full text Add to dashboard Cite

With an increase in fluid densities in centrifugal compressors, fluid-structure interaction and coupled acoustoelastic modes receive growing attention to avoid machine failure. Besides the vibrational behavior of the impeller, acoustic modes building up in the side cavities need to be understood to ensure safe and reliable operation. In a coupled system, these structure and acoustic dominant modes influence each other. Therefore, a comprehensive overview of frequency shift effects in rotor-cavity systems is established based on findings in the literature. Additionally, experimental results on coupled mode pairs in a rotor-cavity test rig with a rotating disk under varying operating conditions are presented. Measurement results for structure dominant modes agree well with theoretical predictions. The development of a forward and a backward traveling wave is demonstrated for each mode in case of disk rotation. Conducted experiments reveal the occurrence of weakly and strongly coupled mode pairs as frequency shifts are observed that cannot solely be explained by “uncoupled mode effects”, such as the added mass, speed of sound, and stiffening effect, but indicate an additional coupling effect. However, the hypothesis of a bigger frequency shift for stronger coupled modes cannot be corroborated consistently. Only for the strongly coupled four nodal diameter mode pair in the “wide cavity” setup, a coupling effect is clearly visible in the form of mode veering.

show abstract

Identification of Coupled Natural Frequencies in a Rotor-Stator Test-Rig for Different Gas Properties

Cited by 3 publications

References 9 publications

Numerical Investigation of Flow and Heat Transfer in a Rotor-Stator Cavity with Centripetal Carbon Dioxide Through-Flow

Numerical Investigation of Flow and Heat Transfer in a Rotor-Stator Cavity with Centripetal Carbon Dioxide Through-Flow

Generalized Model for the Approximation of Coupled Acousto-Mechanical Natural Frequencies in High-Pressure Centrifugal Compressors

Acoustoelastic Modes in Rotor-Cavity Systems: An Overview on Frequency Shift Effects Supported with Measurements

Contact Info

Product

Resources

About