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Abstract: This paper presents the application of two axially-spaced impact detecting sensors for correlation-based shot velocity measurement. The sensors were placed directly into the flow of shot particles for sensing the particles' impact. The implementation of cross-correlation for phase shift determination, however, was not an easy task. Several extensive improvements were necessary, before the original measurement system, already presented in this journal in December 2003, was capable of reliable velocity measurements. This paper presents the development of the system and optimisation of its components. The construction of a sensor built from a small microphone encapsulated in a metal housing and placed under a protective shield was optimised for a high ratio of frontal to side impact signal alteration. High vibration damping was also necessary. It was achieved by the combination of a well-weighted design for supporting elements and by a careful selection of used materials. These measures improved the similarity of the signals generated by the particlesć impact, significantly, and allowed the use of cross-correlation. The accuracy of the obtained results increased drastically by the application of cross-correlation, signal filtering was unnecessary and the signal processing was much faster.
Keywords: velocity measurements, shotblasting
Published: 30.05.2012; Views: 1206; Downloads: 61
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Abstract: Abrasive shotblasting particles and a high concentration of dust within the closed testing chamber make particle velocity measurement in a shotblasting machine very difficult. The application of non-obstructive optical methods is usually impossible. Robust shields protecting the sensors from abrasion have to be used for contacting velocity measurements and make direct application of capacitive or electrodynamic sensors usually applied in the correlation-based velocity measurements methods not possible. An alternative electronic measurement system has been developed. It has a simple construction and uses low cost elements which can be replaced very quickly and, therefore, no robust shields are necessary. This enables very good mobility and positioning of the sensor along both axis in a cross-section plane of a particle stream. The system has been tested along with a robust mechanical measuring device. The development, operation and application of mechanical and electronic particle velocity measurement system are described in this paper. Experimental results are presented, discussed and both methods are compared.
Keywords: shotblasting machines, velocity measurements, particle velocity, mechanical measuring devices, electronic measuring systems
Published: 01.06.2012; Views: 948; Downloads: 39
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Abstract: The results of numerical simulations can be validated experimentally, but usually only the aggregate characteristics are compared. If the aggregate and partial characteristics can be compared at the same time, the level of trust is increased and the physics can be studied in detail. This paper presents a modular measurement system incorporating several devices, including a PIV, traverse system, NI CompactRIO and/or a DAQ, which are synchronized and enable the simultaneous acquisition of aggregate and partial parameters at various sampling frequencies. The modular concept allows for easy configuration and adjustments as needed. The high DI sampling frequency achieved by the CompactRIO system enabled the analysis of trigger delay and significantly increased the AI capability of the PIV system.
Keywords: flow parameter study, velocity profile, measurements, local partial characteristics
Published: 10.07.2015; Views: 411; Downloads: 18
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Abstract: Vsebina diplomskega dela zajema eksperimentalno delo in meritve toka na profil lopatične kaskade v vetrovniku. Zajete tlačne razmere smo pretvorili v sile vzgona in upora. Iz koeficientov vzgona in upora pa smo preučili njihovo odvisnost od napadnega kota.
Keywords: aksialni kompresor, vetrovni kanal, lopatična kaskada, lopatica, koeficient vzgona, koeficient upora, sila vzgona, sila upora.
Published: 25.11.2013; Views: 740; Downloads: 39
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Abstract: V prispevku je predstavljena rešitev problema s hlajenjem motorja, ki se je pojavil, ko smo preskušali tekočinsko hlajeni motor v preskuševališču za zračno hlajene motorje z notranjim zgorevanjem. Vgradili smo toplotni prenosnik voda-voda in mešani ventil s pogonom. Krmiljenje odprtja mešalnega ventila in s tem temperature hladne vode je bilo izvedeno z računalnikom, ki smo ga uporabili tudi za zbiranje podatkov o preskušanju. Sistem je bil preskušen v laboratoriju in omogoča nastavitev želene temperature hladilne vode na vstopu v motor, neodvisno od režima delovanja motorja.
Published: 10.07.2015; Views: 323; Downloads: 19
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