Noise Of Intake System Research Articles

Analysis of flow field and aerodynamic noise of marine gas turbine air intake system.

The aerodynamic noise of air intake system is one of the main noise sources of a gas turbine power plant. In this study, large eddy simulation in conjunction with acoustic finite element method were used to simulate the flow field and acoustic field of the air intake system of marine gas turbine. Based on the acoustic analogy methods, the internal sound source distributions and inlet radiated noise characteristics of the air intake system under different working conditions and wind speeds were analyzed. The simulated flow fields show that the highest vorticity magnitude occurs around the output shaft as the flow largely separates when passing through. The total pressure loss across the intake system increases with the increasing of the air mass flow rate and the ambient wind speed. The acoustical results show that the low frequency noise of the intake system is more prominent than the high frequency noise. The far field sound pressure level increases quadratically with the intake mass flow rates. The introduction of the ambient wind speed at the inlet boundaries reduces the high frequency aerodynamic noise of the intake system, but the overall sound pressure level of the aerodynamic noise increases with the wind speeds.

IC-Engine Exhaust and Intake System Acoustic Source Characterization

The paper gives an overview of techniques used for characterization of IC-engines as acoustic sources of exhaust and intake system noise. Some recent advances regarding nonlinear source models are introduced and discussed. To calculate insertion loss of mufflers or the level of radiated sound information about the engine as an acoustic source is needed. The source model used in the low frequency plane wave range is often the linear time invariant one-port model. The acoustic source data is obtained from experimental tests or from 1-D CFD codes describing the engine gas exchange process. The IC-engine is a high level acoustic source and in most cases not completely linear. It is therefore of interest to have models taking weak non-linearity into account while still maintaining a simple method for interfacing the source model with a linear frequency domain model for the attached exhaust or intake system. The use of source characterization in acoustic design of mufflers is also briefly discussed.

Intake source characterization of a compression ignition engine: Empirical expressions

Unlike exhaust noise, the intake system noise off an automobile cannot be measured because of the proximity of the engine at the point-of measurement. Besides, the intake side is associated with turbocharger (booster),intercooler, cooling fan, etc., which will make the measurement of the intake noise erroneous. Therefore, in the present investigation, the source characteristics of the intake system have been expressed as functions of the engine's physical, operating and thermodynamic parameters. The pressure time history is first computed by means of the commercial software AVL-BOOST for different acoustic loads (induction pipe lengths), which are then used to determine source characteristics, Le.,p(s) and Z(S) (analogous to the open-circuit voltage and internal impedance of an electrical source), using an appropriate multi-load method. This investigation has been conducted for both naturally aspirated and turbocharged diesel engine. Using this methodology and the resultant empirical relations, one can analyze any compression-ignition (CI) engine configuration for the prediction of the un-muffled noise without having to carry out the rather cumbersome and time-consuming time-domain simulation of the intake side. The aim of the present study is to parameterize the source characteristics of an engine in terms of basic engine parameters, so that a first assessment of the un-muffled intake noise can be made by means of the frequency-domain transfer matrix method before a detailed design is taken up.

Virtual design and performance prediction of a silencing air cleaner used in an I.C. engine intake system

This paper reports results of the authors’ studies on the virtual design method used in the development of low noise intake system of I.C. engine. The resulting high pass-by noise at level above the legislative target at full throttle when engine speed was around 5200 r/min necessitated a BEM-aided redesign task, following the typical process of design and development of an intake system. During the initial design, based on the acoustic theory and the requirements (1. The air flux of the redesigned should equal to or exceed the value of the original flux; 2. The filtering area must not be degraded), and considering the constraint of space in the engine compartment, total volume and rough internal dimensions were determined. During the detailed design, the exact internal dimensions of the air cleaner were determined, and an effective method was applied to improve the acoustic performance at low frequency. The predicted sound power of the intake system indicated that the objective of reducing the overall engine noise by minimizing intake system noise was achieved.

강건설계와 열합병법을 이용한 세분화한 흡기계 저소음 최적설계

This paper proposes an optimal design to improve the performance of the intake system by reducing the noise. We adapt the Taguchi method and column merging method for the above design. At the first stage of the design, the length and radius of each component of the current intake system are selected as control factors. Then the <TEX>$L^{18}$</TEX> table of orthogonal array is used to get the effective main factors. At the second stage, the <TEX>$L^{16}$</TEX> table of orthogonal array and the column merging method is combined to analyze subdivided significant factors. We know that the robust design with the column merging method provides better design for noise of intake system than the robust design itself.