The Energy Systems and Turbomachinery Laboratory (EST) at the University of Bergamo, founded in 1997, is provided with the proper equipment and apparatus to carry on the educational and researching mission as well as to meet industrial needs. The main activities deal not only with theoretical and applied research but also with product development/optimisation in collaboration with industrial companies. Services of testing and calibrating flow measurement devices can also be provided. The lab employs two highly skilled technicians to assist with the experimental work.
2 Vane Cascade Wind Tunnels
These are continuously operating, suction-type, open circuit wind tunnels (Fig. 1). A rib turbulator located in the admission channel can be used to increase the inlet turbulence intensity up to 10%. The outer tailboard guides the exhaust region to ensure a proper periodicity. Each wind tunnel delivers a maximum isentropic Mach number M2is
of about 0.7-0.8 at the cascade exit. The test sections allows for the testing of six-bladed linear cascades with a scale factor close to 1:1.
Fig. 1. View of the vane cascade wind tunnels
Rotor Cascade Wind Tunnel
A third wind tunnel (Fig. 2) has been intended to test rotor blade cascades. The concept design is very close to that of the previous one. This wind tunnel delivers a maximum isentropic Mach number M2is
= 0.4 at the cascade exit.
Fig. 2. View of the rotor cascade wind tunnel
Flat Plate Wind Tunnel
It is a low speed, suction type wind tunnel for flat plate film cooling investigation (Fig. 3). The tunnel cross section is 0.2 m × 0.2 m × 1.6 m. The main flow velocity is about 20 m/s. A modular manufacturing of the flat plate allows for easily changing the cooling geometry. Experimental investigations deal with different film cooling hole geometries (Fig. 4).
Fig. 3. Schematic of the flat plate wind tunnel - Fig. 4. Fan shaped vs. cylindrical holes
|Performance of axial and radial fans in terms of characteristic curve, global efficiency and pressure rise versus mass flow rate, at variable rpm, can be estimated.|
- flow rate limit up to 45000 m3/hr
- head limit up to 10000 Pa
- power limit up to 50 kW
|It allows for the heat exchange characterisation both in the liquid-side and in the air-side according to UNI 10531, ARI and ASHRAE rules.|
- air flow rate limit up to 20000 m3/hr
- heat exchange limit up to 150 kW
Brake system - test rig
|It allows to study the aerodynamic and heat transfer behavior of vented discs. An electric motor (3000 rpm maximum speed) gets the disc rotation. The disc rotates in still ambient air at room temperature and pressure, without any forced convection on it. A caliper is fitted to the test rig in its usual position. The test rig is equipped to measure:|
- velocity and temperature of the air at the exit of the cooling channels
- disk temperature and torque both in steady and unsteady regime so that cooling air flow and convective heat transfer coefficient can be obtained.
Probe calibration tunnel
|It is necessary to calibrate the laboratory instruments spanning from aerodynamic pressure probes (three/five-hole), hot-wire anemometers to cold-wire thermometers. Air speed and temperature can be varied up to 120 m/s and 120°C, respectively. The tunnel is equipped with an orthogonal two-axis moving apparatus to allow an automatic collection of angular data during the calibration.|
Prototype of an Absorption chiller
|In the EST Laboratory a prototype of a small size (5 kW) lithium-bromide absorption chiller has been designed and built.|
The system is equipped with electronic instrumentation and of a high level software control in such a way that performance of each component can be evaluated as a function of operating conditions.
Prototype of a Desalination system
|A prototype of a HD (Humidifier-Dehumidifier) desalination unit was designed and assembled in the Bergamo University Labs.|
The units size is about 20 kW; a variable speed blower allows the air to circulate within the closed tunnel. The right-hand vertical column contains the humidification section that consists of nebulizing nozzles. The spatial distribution of nozzles was designed to properly direct the water jets and to maximize the contact surface with air.
Hydraulic bench for refrigeration machinery
This testing facility is designed to carry out experimental investigations on chillers under different operating conditions. It consists of two temperature controllers (a) with 70 kW total thermal power that allow to heat the mass flow rate up to 95°C and of a dry cooling tower system to control the cold source temperature.
|Many measurement techniques are available in the EST laboratory to measure thermos-fluid-dynamic properties of the flow field:|
- Laser Doppler Velocimetry (LDV), hot-wire anemometry (HW), 3 and 5 hole miniaturized aerodynamic probes, Particle Image Velocimetry (PIV)
- cold-wire thermometer (CW), Thermochromic Liquid Crystals (TLC), Pressure Sensitive Paints (PSP), Infra Red thermo camera