- We analyzed formation of small-scale inhomogeneities of particle spatial distribution (particle clustering) in a turbulent flow. The particle clustering is a consequence of a spontaneous breakdown of their homogeneous space distribution, and is caused by a combined effect of the particle inertia and a finite correlation time of the turbulent velocity field. Theory of the particle clustering is extended to the case when the particle Stokes time is larger than the Kolmogorov time scale, but is much smaller than the correlation time at the integral scale of turbulence. The criterion of the clustering instability is obtained. Applications of the analyzed effects to the dynamics of inertial particles in industrial turbulent flows are discussed.