  Gravitational-wave (GW) observations provide unique information about compact
objects. As detectors sensitivity increases, new astrophysical sources of GW
could emerge. Close hyperbolic encounters are one such source class: scattering
of stellar mass compact objects is expected to manifest as GW burst signals in
the frequency band of current detectors. We present the search for GW from
hyperbolic encounters in the second half of the third Advanced LIGO-Virgo
observing run (O3b). We perform a model-informed search with machine-learning
enhanced Coherent WaveBurst algorithm. No significant event has been identified
in addition to known detections of compact binary coalescences. We inject in
the O3b data non-spinning third Post-Newtonian order accurate hyperbolic
encounter model with component masses between [2, 100] $M_{\odot}$, impact
parameter in [60, 100] ${GM}/{c^2}$ and eccentricity in [1.05, 1.6]. We further
discuss the properties of the simulation recovered. For the first time, we
report the sensitivity volume achieved for such sources, which for O3b data
reaches up to 3.9$\pm 1.4 \times 10^5$ Mpc$^3$year for compact objects with
masses between [20, 40] $M_{\odot}$, corresponding to a rate density upper
limit of 0.589$\pm$0.094 $\times10^{-5}$Mpc$^{-3}$year$^{-1}$. Finally, we
present projected sensitive volume for the next observing runs of current
detectors, namely O4 and O5.
