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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2016, Vol. 37 ›› Issue (8): 2436-2444.doi: 10.7527/S1000-6893.2016.0100

• Numerical Simulation Investigations of Unsteady Flow • Previous Articles     Next Articles

Temperature effects on noise in subsonic swirling jets

YANG Haihua1, ZHOU Lin2, WAN Zhenhua1, SUN Dejun1   

  1. 1. Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China;
    2. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 623100, China
  • Received:2016-03-03 Revised:2016-03-24 Online:2016-08-15 Published:2016-04-05
  • Supported by:

    National Natural Science Foundation of China (11232011, 11402262, 11572314);China Postdoctoral Science Foundation (2014M561833);the Fundamental Research Funds for Central Universities of China

Abstract:

Large eddy simulation (LES) is performed for investigating temperature effects in subsonic swirling jets. The effects on the flow development and far-field noise are discussed in detail. The results of linear stability theory show that the growth rates of the shear layers are raised as the core temperature increases; the LES results show that heating promotes the interactions of large-scale structures, makes the flows develop into turbulence more quickly and shortens jet potential cores. At the laminar stage, heating raises the peak of axial velocities fluctuations in center lines; however, it has negligible influence on the peak values in shear layers. At the turbulent stage, as the core temperature increases, the levels of velocity fluctuations become lower and the decay rates become higher. Additionally, it is found that the density fluctuations in non-isothermal jets are much higher than those in isothermal jets. At polar angles near 30°, the overall sound pressure level of the hot jet is lower than that in the isothermal jet and higher than that in the cold jet. However, when polar angle is larger than 50°, heating reduces the sound pressure level and the reduction becomes much larger as polar angle increases. While, the sound pressure level increases slightly in the cold jet.

Key words: swirling jet, large eddy simulation, temperature effect, noise, coherent structure

CLC Number: