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EPG Application Note



In Situ: On - Site & On - Line

Electric Power Generation (EPG) Application Note


A major food retail chain wanted to participate in cost savings derived from utilities sponsored “load shedding / peak shaving” programs.  The concept was further enhanced by having a reliable power source, on each store site, for emergency outages!


After installation of a 1,000 kW engine-generator (EnGen), noise complaints from an adjacent  muffler repair shop, car wash and nearby apartments resulted in a violation notice from the Municipal Environmental Protection Agency (EPA).  The citation mandated a maximum of 65 dBA, during daylight hours, at the property line which was approximately 18 feet from ) the EnGen! 

Figure 1 – EnGen site depicting building and
retaining wall/property line proximity.

Also, during climatically warm days, when load shedding was required, the EnGen’s physical orientation to the architectural building impeded cooling air flow and would not permit maximum electrical loading. (Reference Figure 1)


Aeroacoustic Engineering Consultants, LLC (AEC) was contacted for development of a turn-key remediation to abate the noise citation, improve aerodynamics and return the EnGen to a profitable status.  AEC engineers divided the project into two (2) phases:


Figure 2 – EnGen weather housing before
aeroacoustic modifications with ambient
noise monitoring at property line.

Phase 1:         Determine if the EPA mandated 65 dBA is reasonable and / or achievable within the defacto urban acoustic ambiance (pre-existing background noise). (Reference Figure 2)

Phase 2:         Design, fabricate and install requisite noise suppression hardware to achieve regulatory compliance, meet EnGen manufacturers aerodynamic requirements and all within financial budget constraints of the EPG site.

To accomplish Phase 1, AEC engineers instrumented the property line nearest the EnGen with acoustic and climatic data logging systems.  Rural test sites (Ref. Fig. 3) would have included a global positioning satellite (GPS) system for accurate position location(s) verification and/or future predictive computer simulations (reference, AEC specification sheet number 69900).  Acoustic data and noise spectra are contiguously recorded for the entire test duration (maximum of 100 days of 24-hour contiguous data) and in the engineering units / acoustic descriptors required by governing EPA standards (reference, AEC specification sheet number 29603).  After 15 continuous test hours, with the EnGen locked off, data revealed the sites defacto acoustic ambient (LAeq) was 68.2 dBA without the EnGen running!




To accomplish Phase 2, AEC engineers, armed with the data obtained in Phase 1, initiated the design of a noise abatement system to meet the acoustical, physical and financial constraints imposed by the  EnGen site location.  Three dimensional (3-D), acoustic computer simulations automatically selected the material types and configurations while a computational fluid dynamics (CFD) computer routine monitored system aerodynamics. Both an acoustic and aerodynamic summary is attached with each generic system assembly candidate for the optimum EnGen site performance selection.  When an aeroacoustic remediation configuration has been selected and topographically site adapted, the computer program will generate a shop ready, complete bill of materials (digital production file) ready for fabrication.  This drastic reduction of engineering hours from concept to construction makes custom designs, with optimized aeroacoustic performances, much more convenient and cost effective than “off-the-shelf” hardware that sacrifices system performance for a pseudo inventory of system mis-matched packages.

Figure 3 – Typical rural test site monitoring
acoustics, GPS location and weather data.


Submission of Phase 1 test data to the Municipality resulted in a variance that saved the owner more than $20,000.00 in additional acoustic hardware to meet the original EPA criteria. Post installation aeroacoustic testing verified EnGen site noise reduction satisfied all Municipal, State and Federal EPA noise ordinances, per variance.  Further, improved aerodynamics eliminated troublesome EnGen shutdowns on high temperature days and costly penalties from the utility.  Reduced hardware costs for remediation were within budget constraints and maintained the site profitability and payback schedule.  Overall, the owner received a dependable power generating source that was community friendly and an eager contributor to his financial bottom line. (Reference Figure 4)


Figure 4 – Noise abated configuration
depicting inlet and discharge silencer banks,
 secondary exhaust mufflers and modified
 weather housing for enhanced aerodynamics.


If you have an existing noise problem that requires rehabilitation or are embarking on a proposed project with an acoustic criteria, contact AEC for assistance starting with a telephone consultation.  From engineering services to noise abatement systems through system installation, select any or all from the AEC “aeroacoustic supermarket.”  Just give us a call and let a qualified AEC engineer assist you to establish an effective, guaranteed solution.  Tell us about your noisy problems then, let our over 30 years of experience with noise make your job easier.

Download the PDF Datasheet Below by Clicking on Link


Copyright © 2010 Aeroacoustic Engineering Consultants, LLC
Last modified: March 03, 2011