[en] Full text of publication follows: For the purpose of control of fluid-elastic instability, a general criterion for the design of single-phase heat exchanger tube bundles may be inferred utilizing the results obtained through this experimental investigation. It is immediately apparent that the onset of fluid-elastic instability (FEI) is somewhat ambiguous, both because the process is gradual at the initial stages of onset and differs between different geometric and structural (natural frequency of tube array) configurations. The amplitude of vibration slowly increases as the flow velocity increases and at some point grows very quickly. Any attempt to define a specific critical velocity at which FEI occurs will necessarily be a function of what amplitude is defined as the threshold of instability; this naturally depends on the configurations mentioned above. However, general observations that are more useful than the exact critical velocities may be derived here, especially regarding the overall response of the tube array to the imposed changes in configurations and how they may improve the performance of a given tube bundle design or help to choose between competing design proposals. It is clear from the results that a normal square array configuration is far more susceptible to damaging FEI vibrations than a triangular array configuration over a comparable range of operating velocities. Furthermore, the onset of FEI is much more sudden and violent in the normal square case and, hence, significantly more difficult to predict and prevent. The onset of FEI in normal triangular array configurations varies significantly for each of the different tube frequency tunings. However, the critical velocities of each tuning case for the triangular arrays are greater than those measured for the respective values in the normal square array pattern. Observations of the tube motion for the triangular configuration show a very complex pattern emerging. The pattern appears to be almost statistical in nature with the tubes seeming to behave more independently of one another than the square array, indicating that tube-to-tube coupling may have a reduced influence on the tube vibrations. Data has been collected concerning the vortex-shedding phenomena and its influence on the vibration of the tube arrays under consideration. This data directly provides information for the characterization of the vortex-shedding induced vibration based on the various parameters of the study. Additionally, it allows for the investigation of the possible influence of vortex shedding from the tubes on the onset of FEI, since the vortex shedding phenomena typically occurs at a reduced velocity near that of the FEI onset. The energy associated with the vortex shedding is observed to change significantly as a function of the tube array natural frequency, indicating that the fluid-structure interaction depends heavily on the tuning of the tubes, as suspected. In these respects, observation of the vibrations induced by vortex shedding provide valuable information relevant to the entire scope of the experiment. The reduced velocity range over which the vortex phenomena is prevalent seems to be a primary difference between the FEI onset for the square and triangular configurations. (authors)