0
Research Papers: Fluid-Structure Interaction

Flow-Induced Acoustic Resonance in a Closed Side Branch Under a Low-Pressure Wet Steam Flow

[+] Author and Article Information
Yuta Uchiyama

Central Research Institute of
Electric Power Industry,
2-6-1, Nagasaka,
Yokosuka-shi, Kanagawa 240-0196, Japan
e-mail: uchiyama@criepi.denken.or.jp

Ryo Morita

Central Research Institute of
Electric Power Industry,
2-6-1, Nagasaka,
Yokosuka-shi, Kanagawa 240-0196, Japan
e-mail: ryo@criepi.denken.or.jp

1Corresponding author.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received August 10, 2016; final manuscript received October 27, 2016; published online January 11, 2017. Editor: Young W. Kwon.

J. Pressure Vessel Technol 139(3), 031306 (Jan 11, 2017) (11 pages) Paper No: PVT-16-1132; doi: 10.1115/1.4035271 History: Received August 10, 2016; Revised October 27, 2016

Flow-induced acoustic resonances in piping with closed side branches cause severe structural vibration and fatigue damage of piping and components in power plants. Practical piping systems of power plants often have a steam flow, and moreover, the steam state can be not only dry (i.e., gas single-phase flow with superheated steam) but also wet (i.e., high-quality two-phase flow with mixture of saturated steam and saturated water). Although many researchers have investigated acoustic resonances at side branches, acoustic resonances under a wet steam flow have not yet been clarified since previous studies were mainly conducted under an air flow. Moreover, there have been few previous experiments performed under a steam flow, particularly a wet steam flow. The objective of this study is to investigate acoustic resonances in a closed side branch under a wet steam flow. Experiments on dry and wet steam flows under low pressure and also on an air flow were conducted and the results were compared. Moreover, the applicability of a theoretical equation for the resonance frequency, calculated as the first acoustic mode frequency using the branch piping depth with end correction and the sound speed in dry and wet steam, was evaluated. For our experimental conditions, it was confirmed that the effects of dry steam and air on acoustic resonances were similar. However, higher acoustical damping was confirmed under wet steam than under dry steam, which is considered to be caused by the existing liquid phase (i.e., droplets and/or liquid film). The resonance frequencies under wet steam obtained by the theoretical equation and assuming a saturated sound speed were within ±6% of the measured values, and the critical Strouhal numbers under wet steam were similar to those under dry steam and air when the resonance frequencies were evaluated by the proposed method.

Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Schematic of acoustic resonance in a side branch

Grahic Jump Location
Fig. 2

Schematic of test facility under a steam flow

Grahic Jump Location
Fig. 3

Schematic of the test section

Grahic Jump Location
Fig. 4

Schematic of test facility under an air flow

Grahic Jump Location
Fig. 5

Response curves of (a) RMS amplitude and (b) dominant frequency of the pressure fluctuation at the closed end of the branch. The results for a branch depth of h = 1.045D under dry steam flows with x = 1.06 and 1.03 and an air flow are shown.

Grahic Jump Location
Fig. 6

Typical time histories (left) and frequency spectra (right) of the normalized pressure fluctuation at the closed end of the branch. (a) St = 0.81, (b) St = 0.59, and (c) St = 0.39. The results for a branch depth of h = 1.045D under a dry steam flow with x = 1.03 and an air flow are shown.

Grahic Jump Location
Fig. 7

Effects of scaling law on the response curves of the RMS amplitude of the pressure fluctuation at the closed end of the branch. The vertical axis was normalized by (a) ρUa and (b) ρa2. The results for a branch depth of h = 1.045D under dry steam flows with x = 1.06 and 1.03 and an air flow are shown.

Grahic Jump Location
Fig. 8

Response curves of (a) RMS amplitude and (b) dominant frequency of the pressure fluctuation at the closed end of the branch. The results for a branch depth of h = 1.045D under wet steam flows with x = 0.99, 0.97, and 0.90 are shown.

Grahic Jump Location
Fig. 9

Typical time histories (left) and frequency spectra (right) of the normalized pressure fluctuation at the closed end of the branch. (a) x = 0.99 (St = 0.43), (b) x = 0.97 (St = 0.44), and (c) x = 0.90 (St = 0.47). The results for a branch depth of h = 1.045D under wet steam flows at the values of St where the P*rms reached a maximum are shown.

Grahic Jump Location
Fig. 10

Distribution of the normalized RMS amplitudes at the closed end of the branch. The results for a branch depth of h = 1.045D and St = 0.40 under dry steam conditions with 1.0 < x < 1.07 and St = 0.42 under wet steam conditions with 0.85 < x < 1.0 are shown.

Grahic Jump Location
Fig. 11

Distributions of the RMS amplitude of the pressure fluctuation in the main piping. The results for a branch depth of h = 1.045D and values of St at which the RMS amplitude at the closed end of the branch reached its maximum value are shown.

Grahic Jump Location
Fig. 12

Coefficients of end correction. The results of the dry steam experiments are shown for each steam quality and branch depth.

Grahic Jump Location
Fig. 13

Response curves of the dominant frequency of the pressure fluctuation at the closed end of the branch. The results for a branch depth of h = 1.045D under dry steam flows with x = 1.06 and 1.03 and an air flow obtained by applying the proposed method to evaluate the resonance frequency (Eq. (9)) are shown.

Grahic Jump Location
Fig. 14

Evaluation results of sound speed ratio awet/asat. The results of the wet steam experiments are shown for each steam quality and branch depth. Also shown are previously measured sound speeds in wet steam [15,16] and the mixture sound speeds (Eqs. (7) and (10)).

Grahic Jump Location
Fig. 15

Response curves of the dominant frequency of the pressure fluctuation at the closed end of the branch. The results for a branch depth of h = 1.045D under wet steam flows with x = 0.99, 0.97, and 0.90 obtained by applying the proposed method to evaluate the resonance frequency (Eq. (11)) are shown.

Grahic Jump Location
Fig. 16

Comparison between the resonance frequencies obtained by measurement and theoretical evaluation under dry steam and wet steam

Grahic Jump Location
Fig. 17

Response curves of (a) RMS amplitude and (b) dominant frequency of the pressure fluctuation at the closed end of the branch. The results for a branch depth of h = 1.045D under dry and wet steam flows obtained by applying the proposed evaluation method for the resonance frequency are shown.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In