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Seeding the flow. Experimental results. Seeding of air for PIV-measurements Ronald Kuunders Faculty of Mechanical Engineering, Eindhoven University of Technology. Introduction.
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Seeding the flow Experimental results Seeding of air for PIV-measurements Ronald Kuunders Faculty of Mechanical Engineering, Eindhoven University of Technology Introduction The flow inside an internal combustion engine is of high importance for the combustion, and thus emissions and power. This flow can be measured or simulated. Particle Image Velocimetry produces instantaneous velocity fields. This technique is useful for measuring the turbulence and can be used to validate numerical simulations. PIV uses the displacement of particles in the flow. These particles have to be added and the accuracy of the PIV-measurement depends largely on the properties and numbers of these particles. A rectangle duct flow with an aspect ratio of 2:1 and a Reynolds number of 5300 was investigated. The mass flow of air was 8.3 kg/hour. Titanium oxide particles with a diameter of 1 µm were used during these experiments. The particle production of the seeding-device was 4.8*106 particles a second. The occupancy of the titanium oxide in the ethanol droplets was 1:200. The number of particles can be changed by changing the number of nebulisers or changing the concentration of titanium oxide in the ethanol. The measured velocity-profiles have been compared with the literature. The primary velocity-profiles compared very well. The secondary velocity-profiles differed. The differences were caused by a different inlet and the fact that the flow was not developed yet. The instantaneous velocity-fields were reasonable accurate, the turbulence could be measured. In-cylinder flow The flow inside an engine consists of two main-flows: tumble (left) and swirl (right). Fig. 1 Flow inside an internal combustion engine Fig. 3 velocity-profile of half the channel (left) and an instantaneous velocity map(right). One cylinder of a 9.2 litre truck engine has to be investigated in the future. When motored at 1000 rpm the particle-production has to be 8*106 s-1 to achieve a resolution of 32 x 32 vectors in one cylinder. At first a seeding-device, previously used for LDA-measurements, was used but it did not produce enough particles. The seeding-device produces ethanol droplets with titanium oxide particles in it. The ethanol evaporates and the particles remain. The particle production was improved by placing the nebulisers directly in the airflow. Conclusions • The seeding-device produces enough particles for a PIV-measurement in a rectangle duct. • The primary velocity fields compared well with the literature. • The velocity-maps were showing the turbulence. • The particle-production might be high enough to seed one cylinder of a truck engine for a rough measurement • The particle-production can be altered by changing the number of nebulisers and/or changing the concentration of titanium oxide in ethanol. flowdirection Future work Titaniumoxide in ethanol • Pulsating flow in seeding-device • High pressure test with seeding-device Fig. 2 Cross-section of the seedingdevice Engineering Thesis Committee: Prof. Dr. Ir.R.S.G. Baert , chairman Dr.ir.R.J.M. Bastiaans, coach Dr.ir.H.P.van Kemenade Dr.ir.L.M.T. Somers Dr.ir.C.C.M. Rindt Faculty of Mechanical Engineering Section Combustion Engines
