  Using ideal relativistic hydrodynamics in 2+1 dimensions, we study the
collision energy dependence of radial and elliptic flow, of the emitted hadron
spectra, and of the transverse momentum dependence of several hadronic particle
ratios, covering the range from Alternating Gradient Synchrotron (AGS) to Large
Hadron Collider (LHC) energies. These calculations establish an ideal fluid
dynamic baseline that can be used to assess non-equilibrium features manifest
in future LHC heavy-ion experiments. Contrary to earlier suggestions we find
that a saturation and even decrease of the differential elliptic flow v_2(p_T)
with increasing collision energy cannot be unambiguously associated with the
QCD phase transition.
