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Source Characterization using an Experimental Method and Prediction of Insertion of the Exhaust System

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2018, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Exhaust systems are designed for reducing the noise coming out of the engine as well as controlling air pollution. In this study, the noise abatement process of exhaust systems and its predictions are the primary points of focus. The evaluation of the acoustic performance of an exhaust system at the design stage requires a correlated engine model and reasonably approximate input boundary conditions to simulate the end results, both of which are not easily available. It is known that the input boundary conditions for insertion loss analysis require two engine parameters namely, source impedance and source strength spectra. This research describes experimental measurements for these parameters using in-duct measurement via the multi-load method for a six-cylinder diesel engine, and calculation for insertion loss using GT-Power®. The research discusses the approach taken to select the acoustic load cases considered for the multi-load method and then the execution of the test plan for different engine operating conditions using six different transducers to record the dynamic pressure, temperature and engine vibrations. The time domain data sets were processed to obtain the frequency spectra and frequency response functions between two dynamic pressure signals. The frequency domain data was used to get the impedance of the acoustic load cases and finally the source impedance and source strength spectra for different engine operating conditions. The results obtained using all the acoustic load cases were optimized by filtering out unacceptable load cases and then re-evaluating the source characteristics to use them as input boundary conditions for insertion loss analysis. The analysis results were then compared to the experimental insertion loss. The above-mentioned approach for the engine was deployed to characterize a random noise source, i.e. a speaker, using six different load cases. The experimental insertion loss was evaluated and compared against the insertion loss spectrum obtained from GT-Power® insertion loss analysis using speaker impedance and speaker strength as input boundary conditions.
Randall Allemang, Ph.D. (Committee Chair)
Allyn Phillips, Ph.D. (Committee Member)
Yongfeng Xu, Ph.D. (Committee Member)
107 p.

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Citations

  • Chhabra, M. (2018). Source Characterization using an Experimental Method and Prediction of Insertion of the Exhaust System [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin154399673454236

    APA Style (7th edition)

  • Chhabra, Manish. Source Characterization using an Experimental Method and Prediction of Insertion of the Exhaust System. 2018. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin154399673454236.

    MLA Style (8th edition)

  • Chhabra, Manish. "Source Characterization using an Experimental Method and Prediction of Insertion of the Exhaust System." Master's thesis, University of Cincinnati, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin154399673454236

    Chicago Manual of Style (17th edition)