Session: 01-08-01: Flow-Induced Noise and Vibration

Paper Number: 112615

112615 - Revisiting and Improving Pipe Wall Transmission Loss Estimation for Control Valve Noise Prediction 

Nearly all industrial control valve applications require an estimate of the sound level in the vicinity of the valve and immediate downstream piping. These predictions are necessary to select the correct control valve design for the end user to keep their employees and equipment safe as well as meet any local noise ordinances. In a piping system any noise generated by a valve or other source will propagate through the downstream pipe. This internal acoustic field will couple to the pipe wall and cause it to vibrate, which in turn causes external radiation. The difference between the internal and external sound fields is called transmission loss. The estimation of the transmission loss can be a major contributor to the accuracy of noise prediction methods.

The theory that is the basis of the pipe wall transmission loss calculation in the international standard IEC 60534-8-3 Control Valve Aerodynamic Noise Prediction Method uses Statistical Energy Analysis (SEA) methods. The use of SEA allows an evaluation of transmission loss in frequency ranges where the number of acoustic and structural modes are unrealistic to analyze discretely, and average behavior can be used to predict with reasonable accuracy. This type of reduced order analysis is critical because at times initial noise estimates are required to determine which valves may need noise reduction capability. This may be done before details of the piping system are known since piping changes can occur as the overall facility design progresses.

The transmission loss background theory is reanalyzed to correct an error and reevaluate the impact of critical variables within this paper. One critical variable is the presence of uniform mean flow which in previous analysis showed it could have a significant impact on the prediction of transmission loss at higher Mach numbers. The current analysis shows that the theoretical impact is much less prominent and primarily changes the pipe internal acoustic modal density. The pipe internal acoustic modal density is another critical factor which is investigated and compared with a few of the analytical calculations used in more recent SEA references.

Based on the complete reanalysis, suggestions for improvements to the calculation methodology used in noise predictions are provided and the estimated change is quantified. Experimental test data was taken in a flow system designed to measure control valve noise. The system can test a range of pipe diameters and operate at high pressures and flow rates. This experimental data is compared to the improved methodology to justify the recommended changes.

Presenting Author: Daniel Eilers Emerson Automation Solutions - Fisher Valves

Presenting Author Biography: Dan Eilers is a Research Specialist at Emerson Automation Solutions – Fisher Valves. He has a Master of Engineering from Iowa State University with a focus on fluid dynamics and acoustics. In over 16 years at Emerson, Dan has worked in experimental, computational, and analytical roles and has been awarded 16 patents. He is an active contributor to US and international control valve standards particularly in the area of noise measurement and prediction.

Authors:

Daniel Eilers Emerson Automation Solutions - Fisher Valves
Allen Fagerlund Emerson - Fisher Heritage