Novel Carbon Fibre Composite Centrifugal Impeller Design, Numerical Analysis, Manufacturing and Experimental Evaluations.

Radu Mihalache,Ion Malael,Ionut Sebastian Vintila,Dragos Mihai,Mihail Sima,Alexandru Tudorache,Marius Deaconu

doi:10.3390/polym13193432

Radu Mihalache, Ion Malael + Show 5 more

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https://doi.org/10.3390/polym13193432

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Abstract

This paper presents an experimental investigation on using high strength-to-weight composite materials to reduce the mass of a centrifugal compressor impeller by 600%. By reducing the blades number from 17 to 7 and by doubling their thickness, the compression ratio and efficiency were maintained close to the reference metallic impeller. Using autoclave technology, seven composite blades were manufactured individually and assembled to form the impeller. After manufacturing, small deviations were found at the blade’s tip. As these deviations were found to be symmetrical, impeller balancing was successfully performed removing a total of 45 g of mass, followed by an experimental test on a dedicated test bench. Experimental testing identified the resonant frequencies of the composite centrifugal impeller at 13.43 Hz 805 rot/min and at 77 Hz with a 0.1 mm/s amplitude at 4400 rot/min, highlighting feasibility and the advantage of a composite compressor impeller design with application in centrifugal compressors and rotating machine assemblies and sub-assemblies. As there are numerous numerical investigations performed on the strength analysis and on the lay-up orientations mechanical behaviour for polymer composite materials with respect to the design of centrifugal impellers, no experimental evaluations in relevant working conditions have been performed to date. As the paper contains relevant experimental data on the subject, the outcome of the paper may aid the oil and gas or aviation industries.

Highlights

Up to 20% energy savings can be achieved by using composite impellers [3,4], as their lower weight reduces the start-up loads and shaft deflections, allowing the composite rotating part to run with tighter clearance increasing the efficiency
First critical frequency was identified at 12 Hz (960 rot/min), which corresponds to a conical Eigenvalue; this does not affect the working regime of the impeller, as the speed is constantly increasing up to the nominal operating speed of 17,250 rot/min
A new design dedicated for autoclave technology was proposed and experimentally evaluated for a carbon fibre reinforced polymer (CFRP) composite centrifugal impeller

Summary

Introduction

The aim is to reduce the environmental impact of these pollutants and their effects on climate change. Such pollutant reductions can be achieved by weight reduction in overall assemblies with focus on rotary sub-assemblies in industrial machines and in gas turbines. As carbon fibre composite materials offer a wellknown low-mass high-strength ratio and are used considerably in the aviation industry, these materials have gained interest in the oil and gas industry for manufacturing of risers, drill pipes and tubing, pressure vessels, tanks and pipe systems for fluid transport [1], but not yet in the rotary assemblies or sub-assemblies. Up to 20% energy savings can be achieved by using composite impellers [3,4], as their lower weight reduces the start-up loads and shaft deflections, allowing the composite rotating part to run with tighter clearance increasing the efficiency

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