• Title/Summary/Keyword: Inlet function

Search Result 168, Processing Time 0.018 seconds

Optimum Design for Inlet and Outlet Locations of Rectangular Expansion Chamber for Improving Acoustic Performance (사각형 단순 확장소음기의 성능향상을 위한 입$\cdot$출구 위치의 최적설계)

  • 김봉준;정의봉;황상문
    • Journal of KSNVE
    • /
    • v.9 no.4
    • /
    • pp.738-746
    • /
    • 1999
  • The performance of muffler can be improved for a frequency range of interest by moving inlet and outlet locations. And optimal location of inlet and outlet can be determined to improve the acoustic performance. The optimum design using FEM, however, may take a very long time and be very hard to take inlet and outlet locations as design variables. In this paper, the acoustic performance of reactive type single expansion chamber muffler is predicted using higher order mode theory. The sensitivity analysis of transmission loss with respect to the location of inlet and outlet is suggested. And the acoustic power transmission coefficient for a frequency of interest is used as cost function. Optimum location of inlet and outlet is determined to minimize cost function by using SUMT algorithm.

  • PDF

Shape Optimization of Inlet Part of a PCHE (인쇄형 열교환기 입구부의 최적설계)

  • Koo, Gyoung-Wan;Lee, Sang-Moon;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
    • /
    • v.16 no.2
    • /
    • pp.35-41
    • /
    • 2013
  • Inlet part of a printed circuit heat exchanger has been optimized by using three-dimensional Reynolds-Averaged Navier-Stokes analysis and surrogate modeling techniques. Kriging model has been used as the surrogate model. The objective function for the optimization has been defined as a linear combination of uniformity of mass flow rate and the pressure loss with a weighting factor. For the optimization, the angle of the inlet plenum wall, radius of curvature of the inlet plenum wall, and width of the inlet pipes have been selected as design variables. Twenty six design points are obtained by Latin Hypercube Sampling in design space. Through the optimization, considerable improvement in the objective function has been obtained in comparison with the reference design of PCHE.

Analysis and Improvement for Performance of the Muffler of a Tracter (트랙터 소음기의 성능해석 및 개선에 관한 연구)

  • 이규태;도중석;오재응
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.4
    • /
    • pp.151-159
    • /
    • 1998
  • The heavy equipment such as tracter has been studied to improve rather the performance of engine than comfort. The mufflers of tracters have various specifications according to their uses. The exact analysis of various mufflers is needed to reduce the level of exhaust moise, a major noise source of engine, to improve the ride quality of tracter. In this study, a software based on Green's function is developed to predict the performance of sound transmission loss for a muffler according to the locations of inlet/outlet pipes. The locations of inlet and outlet pipes can be fixed at different position individually. The conventional muffler has the locations of inlet/outlet pipes on the direction of longitudinal axes. On other hand, the inlet and outlet pipes may be located at the circumferential surface of a test muffler such as one of tracter. The software is verified by analysis and experiment on current muffler of tracter and the improvement technique is proposed to reduce the level of exhaust noise.

  • PDF

Flame Dynamic Response to Inlet Flow Perturbation in a Turbulent Premixed Combustor (난류 예혼합 연소기에서의 흡입 유동 섭동에 대한 화염의 동적 거동)

  • Kim, Dae-Sik
    • Journal of the Korean Society of Combustion
    • /
    • v.14 no.4
    • /
    • pp.48-53
    • /
    • 2009
  • This paper describes the forced flame response in a turbulent premixed gas turbine combustor. The fuel was premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. To impose the inlet flow velocity, a siren type modulation device was developed using an AC motor, rotating and static plates. Measurements were made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The test results showed that flame length as well as geometry was strongly dependent upon modulation frequency in addition to operating conditions such as inlet velocity. Convection delay time between the velocity perturbation and heat release fluctuations was calculated using phase information of the transfer function, which agreed well with the results of flame length measurements. Also, basic characteristics of the flame nonlinear response shown in the current test conditions were introduced.

  • PDF

Flame Transfer Function Measurement in a Premixed Combustor (예혼합 연소기에서의 화염 전달 함수 측정)

  • Kim, Dae-Sik;Kim, Ki-Tae;Chen, Seung-Bae;Lee, Jong-Guen;Santavicca, Domenic
    • Journal of the Korean Society of Combustion
    • /
    • v.13 no.2
    • /
    • pp.1-6
    • /
    • 2008
  • An experimental study of the flame response in a turbulent premixed combustor has been conducted with room temperature, atmospheric pressure inlet conditions using premixed natural gas. The fuel is premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. Therefore the observed flame response is only the result of the imposed velocity fluctuations, which are produced using a variable speed siren. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function as a function of the modulation frequency. Of particular interest is the effect of flame structure on the flame response predictions and measurements. The results show that both the gain and the phase of flame transfer function are closely associated with the flame length and structure, which is dependent upon the upstream flow perturbation as well as equivalence ratio in the current study.

  • PDF

Transmission Loss Analysis of Simple Expansion Chambers with Multiple Inlets and Outlets (다입력/다출력관을 갖는 확장관의 투과손실 해석)

  • 박기춘;김양한
    • Journal of KSNVE
    • /
    • v.8 no.5
    • /
    • pp.807-813
    • /
    • 1998
  • Transmission loss of the simple expansion chamber with multiple inlet and outlet ports is obtained. Transfer matrices which represent the relation between the power variables(pressure and velocity) of inlets and outlets depend on the input relatons as well as the acoustic system parameters(i.e. geometry of the chamber, wall admittance, etc.). The analysis has been performed analytically, including the effects of higher order modes for the 2-inlet/1-outlet, 1-inlet/2-outlet and 2-inlet/2-outlet systems. This study yeilds that phase difference between the inlet ports can significantly increase the transmission loss in low frequency range.

  • PDF

Effects of Inlet Turbulence Conditions and Near-wall Treatment Methods on Heat Transfer Prediction over Gas Turbine Vanes

  • Bak, Jeong-Gyu;Cho, Jinsoo;Lee, Seawook;Kang, Young Seok
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.17 no.1
    • /
    • pp.8-19
    • /
    • 2016
  • This paper investigates the effects of inlet turbulence conditions and near-wall treatment methods on the heat transfer prediction of gas turbine vanes within the range of engine relevant turbulence conditions. The two near-wall treatment methods, the wall-function and low-Reynolds number method, were combined with the SST and ${\omega}RSM$ turbulence model. Additionally, the RNG $k-{\varepsilon}$, SSG RSM, and $SST_+{\gamma}-Re_{\theta}$ transition model were adopted for the purpose of comparison. All computations were conducted using a commercial CFD code, CFX, considering a three-dimensional, steady, compressible flow. The conjugate heat transfer method was applied to all simulation cases with internally cooled NASA turbine vanes. The CFD results at mid-span were compared with the measured data under different inlet turbulence conditions. In the SST solutions, on the pressure side, both the wall-function and low-Reynolds number method exhibited a reasonable agreement with the measured data. On the suction side, however, both wall-function and low-Reynolds number method failed to predict the variations of heat transfer coefficient and temperature caused by boundary layer flow transition. In the ${\omega}RSM$ results, the wall-function showed reasonable predictions for both the heat transfer coefficient and temperature variations including flow transition onset on suction side, but, low-Reynolds methods did not properly capture the variation of the heat transfer coefficient. The $SST_+{\gamma}-Re_{\theta}$ transition model showed variation of the heat transfer coefficient on the transition regions, but did not capture the proper transition onset location, and was found to be much more sensitive to the inlet turbulence length scale. Overall, the Reynolds stress model and wall function configuration showed the reasonable predictions in presented cases.

Study on Characteristics of Spray Combustion for Various Operation Conditions in a Gas Turbine Combustor (가스터빈 연소기 내 운전조건 변화에 따른 분무연소 특성 연구)

  • Cho, S.P.;Kim, H.Y.;Park, S.
    • 한국연소학회:학술대회논문집
    • /
    • 2002.06a
    • /
    • pp.3-10
    • /
    • 2002
  • In this work, numerical parametric studies on spray combustion have been conducted. In simulation of turbulence, RNG ${\kappa}-{\varepsilon}model$ is adopted. Initial spray distribution is specified by Rosin-Rammler distribution function. Eddy break-up model is adopted as a combustion model. The parameters considered are inlet air temperature, swirl number, and SMD. With higher inlet air temperature, the axial velocities are increased and penetration of primary jet is stronger than that of lower inlet air temperature and temperature at the exit of combustor is more uniform. Combustion efficiency is improved with high inlet air temperature. The effect of swirl number on flow field is not significant. It affect only recirculation zone. So temperature at upstream of combustor is influenced. Combustion efficiency deteriorate as SMD of fuel spray increase.

  • PDF

Inverse Problem of Determining Unknown Inlet Temperature Profile in Two Phase Laminar Flow in a Parallel Plate Duct by Using Regularization Method (조정법을 이용한 덕트 내의 이상 층류 유동에 대한 입구 온도분포 역해석)

  • Hong, Yun-Ky;Baek, Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.28 no.9
    • /
    • pp.1124-1132
    • /
    • 2004
  • The inverse problem of determining unknown inlet temperature in thermally developing, hydrodynamically developed two phase laminar flow in a parallel plate duct is considered. The inlet temperature profile is determined by measuring temperature in the flow field. No prior information is needed for the functional form of the inlet temperature profile. The inverse convection problem is solved by minimizing the objective function with regularization method. The conjugate gradient method as iterative method and the Tikhonov regularization method are employed. The effects of the functional form of inlet temperature, the number of measurement points and the measurement errors are investigated. The accuracy and efficiency of these two methods are compared and discussed.

Optimum Design for Inlet and Outlet Locations of Circular Expansion Chamber for Improving Acoustic Performance (원형 단순 확장소음기의 성능향상을 위한 입.출구 위치의 최적설계)

  • An, Se-Jin;Kim, Bong-Jun;Jeong, Ui-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.10 s.181
    • /
    • pp.2487-2495
    • /
    • 2000
  • The acoustic characteristics of expansion chamber will be changed with the variation of inlet/outlet location due to the higher order acoustic mode in a high frequency in which the plane wave theory is not available. In this paper, the acoustic performance of reactive type expansion chamber with circular cross-section is analyzed by using the modified mode matching theory. The sensitivity analysis of four-pole parameters with respect to the location of inlet and outlet is also suggested to increase the acoustic performance. The acoustic power transmission coefficient is used as cost function, and the location of inlet and outlet is used as design variables. The steepest descent method and SUMT algorithm are used for optimization technique. Several results showed that the expansion chamber with optimally located inlet/outlet had better acoustic performance than concentric expansion chamber.