Toward understanding the mass flow generate noise in the inlet duct engine measurement

Performance Improvements of Centrifugal Compressors Through Shroud Cavity Leakage Management

Volume 6C: Turbomachinery ◽

10.1115/gt2013-95809 ◽

2013 ◽

Author(s):

A. M. Basol ◽

R. S. Abhari

Keyword(s):

Mass Flow ◽

Static Pressure ◽

Side Wall ◽

Meridional Flow ◽

Flow Coefficient ◽

Final Conclusion ◽

Leakage Flow ◽

Lower Efficiency ◽

Inlet Duct ◽

Duct Design

This study numerically investigated the effects of the geometry modifications in the vicinity of the shroud cavity area of a high flow coefficient, multi-stage, inline centrifugal compressor on its efficiency. The modifications in the shroud cavity area cover the lean of the seal teeth geometries and their streamwise positioning. The baseline four teeth seal geometry has been modified which resulted in 15 % reduction in the leakage mass flow and increased the compressor’s efficiency by 0.17 % by even reducing the number of the teeth to three. Modifications in the radial inlet duct geometry aimed to reduce the pressure difference across the shroud cavity by providing further static pressure recovery at the shroud cavity outlet. The modified inlet duct design resulted in a further 0.13 % rise in efficiency in spite of the minor 4 % additional drop in the leakage mass flow. The modified inlet duct performed better only in presence of the shroud cavity leakage flow. Excluding the leakage the modified inlet duct resulted in a lower efficiency value compared to the efficiency value obtained with the existing inlet duct. These findings point out a possible reduction in the mixing loss between the main flow and the shroud cavity leakage flow with the modified inlet duct design which reduced the Mach number level close to the shroud side wall due to the increased static pressure. As the final conclusion on the design of the radial compressors this work shows the importance of considering the leakages at the early stages of the compressor design even deciding on the meridional flow path.

Download Full-text

Design and Characterization of an Inlet Duct for Mass Flow Measurement in a Micro Gas Turbine Test Rig

Volume 1B: Marine; Microturbines, Turbochargers and Small Turbomachines; Steam Turbines ◽

10.1115/gt2014-25391 ◽

2014 ◽

Author(s):

C. Buratto ◽

A. Carandina ◽

M. Morini ◽

C. Pavan ◽

M. Pinelli ◽

...

Keyword(s):

Noise Reduction ◽

Gas Turbine ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Pressure Loss ◽

Resistive Load ◽

Test Rig ◽

Micro Gas Turbine ◽

Inlet Duct

In this paper, a test rig for experimentation on a micro gas turbine is presented. The test rig consists of a micro gas turbine Solar T-62T-32, which, coupled with a 50 kVA alternator, can supply electrical energy to a calibrated resistive load bank. Particular attention is paid to the design of the inlet duct for the mass flow rate measurement. The basic issue was to create the intake duct for a micro gas turbine (MGT) test rig, in order to provide precise data about the mass flow rate and the thermodynamic air characteristics in the MGT inlet section. The inlet duct is also designed in order to allow future tests on inlet cooling technologies. The MGT is incorporated in a chassis for noise reduction, the dimensions of which are 540 mm (height), 570 mm (width) and 940 mm (length). These small dimensions lead to problems with the insertion of the duct. Moreover, the intake of the compressor is not axial but radial, and this means that a volute must be foreseen to convey the flux into the MGT. Several shapes of volute are analyzed in this paper, considering the effects on the pressure loss and the induction of turbulence. The challenge was to develop a fluid-dynamically efficient duct with the hindrance of a very small available space between the compressor casing, the gearbox and the fuel pipes inside the narrow noise-reduction chassis. The mass flow rate will be computed by means of the differential static pressure between the upstream and the downstream section of a Venturi tube. The choice of a Venturi was due to the fact that it produces a pressure loss lower than any other device, such as orifice plates or other nozzle shapes. Furthermore, the expected mass flow rate would lead to high fluid speeds and, as a consequence, the diameter ratio between the duct and the throat of the Venturi was chosen to be as high as possible.

Download Full-text

Design of Duct Passages for an Air Turbine Starter Test Rig

10.1115/gtindia2021-76152 ◽

2021 ◽

Author(s):

Sadham Usean R ◽

Prasad B. V. S. S. S. ◽

Milind Dhabade ◽

Amit Kurvinkop ◽

Vishnuvardhan Tatiparthi

Keyword(s):

Pressure Drop ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Test Rig ◽

Lower Efficiency ◽

Exhaust Duct ◽

Air Turbine ◽

Transition Piece ◽

Inlet Duct

Abstract In a typical air turbine starter (ATS) engine testing application, compressed air is supplied to the turbine by means of an inlet duct usually with a 90 degree bend and discharged from the turbine into the exhaust chimney through a combination of two duct passages. The primary duct is integral to the engine for connecting to the containment ring. The secondary duct is a transition piece for connecting to the exhaust chimney. As these ducts consume additional pressure and adversely affect the performance of the ATS under test. The design of pressure-efficient outlet ducts is therefore essential, and is the topic of present study. The aerodynamic performance of the overall passage depends on the (i) angle of bend, (ii) the shape of the connecting bolt, (iii) the outlet area and shape of the exhaust duct transiting between the bend and the chimney. Combinations of different angular bends, different shaped bolts and varying size of transition pieces are analyzed using the enterprise version of CFD tool, ANSYS. Three dimensional mesh independent simulations using k-epsilon turbulence model are carried out for a combined geometry of inlet duct, rotor-stator combination, outlet ducts together with the bolts. A combination of the duct passages that has resulted in lowest possible pressure drop is suggested as result of the study i.e. the 90 degree bend duct gives 9% pressure difference between inlet and outlet and this might slightly affect the efficiency of the air turbine stator, however the mass flow rate values remains similar to the stator inlet mass flow rate. Hence the 90 degree bend duct is suitable for the test rig. The static pressure loss and total pressure gain is about 0.04% and −0.004% respectively for baseline and aggressive duct of stator and rotor, hence the baseline duct profile is better than aggressive duct. Among different shapes of connecting bolt, the baseline geometry gives slightly lower efficiency of 85.6% when compared to all other models. But due to manufacturing feasibility the baseline geometry is preferred. Exhaust duct model 7 gives pressure drop as 0.062 bar twice the amount of pressure drop in model 6, but it does not affect the efficiency of air turbine starter. The shapes and sizes of the bend, bolts and the transition piece are recommended.

Download Full-text