This paper describes the effort of designing an unconventional exhaust manifold for a marine gas turbine engine, with an integrated passive ventilation port for cooling the engine housing. The study is part of a larger program to substitute the propulsion gas turbines for the T22R defense frigate and make the proper aerodynamic adaptations. The system in question is unique, in the sense that it uses the exhaust gas momentum to entrain outside air and ventilate the engine enclosure. In achieving this, RANS computation was used to test various concepts and dimensions for the ventilation system. Based on these analyses, the design that provided adequate air circulation with minimum pressure losses was chosen and the parts were integrated in the overall assembly. The experimental campaign performed on the entire aero-package showed good synergies of the ventilation system with the other adaptations and the engine itself. Performance was evaluated with pressure and temperature probes distributed around the aero-package and were found to be within 3.5% of the data predicted by CFD. This brings further studies closer to a technology readiness level vital for insitu testing on board the ship itself.

The transient regimes in a combustion chamber has to be as short as possible because flame front position and thickness can destroy the combustion chamber in couple seconds. The simulation of such a regime has to be performed unsteady. An experimental combustion chamber it is simulated at two unsteady regimes to see the flame front structure and comparison it is made with the experimental data to validate the results. For this analysis Ansys CFX was used and the turbulent model was DES while the combustion model was Eddy Dissipation. The two cases show different flame front structures while the boundary conditions for the two regimes are very similar.

There is a need for centrifugal blowers to adapt to different operating conditions in order to meet the user requirements, in a high efficiency manner. Variable Inlet Guided Vanes (known as IGVs) are a simple solution which can lead to important energy savings. The IGV consists of wedge-shaped steel blades mounted around the inside circumference of a short length inlet pipe, with the purpose to restrict, or increase the inlet flow area, thus controlling the mass flow. The aim of this research is to determine the optimal distance between the IGV and the rotor in order to achieve maximum efficiency. The study will focus on the pressure losses and the separation of the boundary layer at the different lengths, for a fixed angle of the IGV of 45 degrees. For this study, the commercial CFD software Ansys CFX will be used to estimate the efficiency of the rotor for different set-ups, via a 3D steady-state numerical flow analysis. The end results of this study will help correlate the position of the IGV to the efficiency of the blower and to determine the optimal distance between the rotor and the IGV for an increased performance.

Turbomachinery shock wave patterns occur as a natural result of operating at off-design points and are accountable for some of the loss in performance. In some cases, shock wave–boundary layer (SW-BLIs) interactions may even lead to map restrictions. The current paper refers to experimental findings on a transonic linear cascade specifically designed to mitigate shock waves using porous walls on the blades. Schlieren visualization reveals two phenomena: Firstly, the shock waves were dissipated in all bladed passages, as predicted by the CFD studies. Secondly, a lower-pressure wave pattern was observed upstream of the blades. It is this phenomenon that the paper reports and attempts to describe. Attempts to replicate this pattern using Reynolds-averaged Navier–Stokes (RANS) calculations indicate that the numerical method may be too dissipative to accurately capture it. The experimental campaign demonstrated a 4% increase in flow rate, accompanied by minimal variations in pressure and temperature, highlighting the potential of this approach for enhancing turbomachinery performance.

In this paper, the effect on a perforated plate on a centrifugal compressor is investigated using numerical simulation. The performances and fluid flow are compared for two different vaned diffusers, a base case where there are no perforated plates and a case where a perforated plate is inserted in the rotor casing at exit and the stator blade. The impact of this geometry change on the compressor performances it is studied in the case of adverse angles of attack at stator vane. Near wall refinement ensures the accuracy resolution of the boundary layer with a y+ value of one unit corroborated with a growth ratio of 1.1:1. Menter’s SST model was used in all numerical cases performed, as implemented in ANSYS CFX. Following the results of the baseline diffuser, the optimal position of the perforated cavity was determined.

In this article will be described the improved test stand for rotating labyrinth seals that will be developed at COMOTI. The present test rig is able to test only a seal configuration in a simplified environment, (air temperature max.150° C, labyrinth diameter max. 300 mm, airflow rate max. 0.35 kg/s, pressure max. 9 bars). The newly improved research infrastructure will be able to increase these limits up to: 800°C temperature, 600 mm labyrinth diameter, 10 kg/s airflow rate and 50 bars pressure. The upgrade performed on to this research facility will comprise of a test rig for experimental measurements; a air supply station with two centrifugal compressors; an air cooling tower; a air tank to store high pressure air and an air heater station capable to supply air with 800°C.