Tag Archives: airflow

xxx J. Čedík, J. Chyba, M. Pexa and S. Petrásek
Influence of shape of cutting tool on pressure conditions in workspace of mulcher with vertical axis of rotation
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Influence of shape of cutting tool on pressure conditions in workspace of mulcher with vertical axis of rotation

J. Čedík¹*, J. Chyba², M. Pexa¹ and S. Petrásek²

¹Czech University of Life Sciences, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ16521, Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

Nowadays there is laid great insistence on work efficiency improvement. This effort also affects the construction of mowers such as mulchers. Mulching with a vertical axis of rotation is very energy demanding work operation mainly, due to high energy losses. These energy losses, but also the quality of work, are influenced by the airflow and associated conditions of pressure inside the workspace of mulcher. Airflow in the workspace ensures repetitious contact of the truncated forage crops with the cutting edge tool and thus ensures crushing of aboveground parts of plants. The paper deals with the influence of the cutting tool shape on the mulcher’s inside workspace pressure conditions with the vertical axis of rotation. The influence of the trailing edge angle and rake angle on the pressure profile in the mulcher’s workspace with dependence on the rotor speed was examined. Measurements were performed on a laboratory single rotor mulcher model. It was found that in the mulcher’s workspace the vacuum is formed by virtue of the rotary movement of the cutting tools wherein the vacuum increases with rotor speed. The maximum measured vacuum was about 2.4 kPa and from the centre of the rotor towards its circumference almost linearly decreases. Furthermore, it was found that with decreasing trailing edge angle and with increasing rake angle the maximum vacuum decreases. When reducing the angle of the trailing edge from 45° to 25° led to reduction of vacuum of about 0.3 kPa (12.6%).

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111-116 T. Šima,, J. Krupička and L. Nozdrovický
Effect of nitrification inhibitors on fertiliser particle size distribution of the DASA® 26/13 and ENSIN® fertilisers
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Effect of nitrification inhibitors on fertiliser particle size distribution of the DASA® 26/13 and ENSIN® fertilisers

T. Šima¹,*, J. Krupička² and L. Nozdrovický³

1,3Slovak University of Agriculture in Nitra, Faculty of Engineering,Department of Machines and Production Systems, Tr. A. Hlinku 2, 94976 Nitra,Slovak Republic; *Correspondence: tomasko.sima@gmail.com
²Czech University of Life Sciences Prague, Faculty of Engineering, Departmentof Agricultural Machines, Kamýcká 129, 16521 Prague, Czech Republic

Abstract:

Effectiveness of the spinning disc fertiliser spreaders is affected by the physicalproperties of the fertiliser. One of the most important factors is the fertiliser particle-sizedistribution which depends upon the size of the fertiliser particles. The aim of the paper wascomparison of two very similar fertilisers from the same manufacturer DUSLO, Inc. usinggranulated nitrogen fertiliser with sulphur content DASA® 26/13 and nitrogen fertiliserENSIN® containing sulphur and nitrification inhibitors dicyandiamide DCD and 1, 2, 4 triazole– TZ. Comparison was done by evaluation of the particle-size distribution of the fertiliserseparated at first in the vertical air flow by K-293 Laboratory screening machine with steeplyincreasing flow speed. The airflow speed was regulated by airflow volume from 60 to 150 m3 h-1. Secondary separation was done by sieve screening of the samples by Haver EML digital plusTest Sieve Shaker. Sieves with square holes with dimensions 1 mm, 2 mm, 3.15 mm, 5 and10 mm were used. Both fertilisers meet the requirements of the manufacturer for grain-sizedistribution. Air flow separation shows higher variability of weight of the ENSIN fertiliserparticles in comparison with DASA fertiliser. Air flow 130 m3 h-1 separated all the particles ofDASA fertiliser. To separate all ENSIN® particles there was used air flow to 150 m3 h-1. Thesedifferences affect the quality of work of the spinning disc fertiliser spreader and cause non-uniformity in the field distribution of fertiliser which has negative environmental andeconomical effects.

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