Experimental researches are carried out on bubble flow and slug flow of flow around bluff body in horizontal gas-liquid two-phase flow.Stability of vortex street is analyzed based on repeatability

variation trend of St and correlation research of St with changing volume void fraction.It is concluded that the flow field can produce a stable vortex street when volume void fraction is within 15 % but the stable vortex street is destroyed and it can still produce vortex street when volume void fraction is greater than 15 %.Experimental studies show that the results of three methods are consistent and have good stability.