Improved methods of aerodynamic testing of current collector by considering ambient air density

Aerodynamic forces of current collector depend not only on the design parameters, but also on weather conditions determining the dynamic pressure. Currently, when conducting field tests, control of these conditions is not performed, this can affect the accuracy of the results. The objectivity of measurements can be provided by theoretical and experimental methods of accounting air density. A theoretical method based on the calculation of the density of air environment by using data about the temperature, atmospheric pressure and relative humidity in the area where tests of current collector was conducted. The experimental method involves the use of ultrasonic density meter of air. Density values, defined experimentally, increase the accuracy of the results due to the fact that registration takes place directly on the roof of the locomotive, where the current collection was performed. It is shown that the dependence of the vertical component of the aerodynamic forces of current collector from the air density is linear. The article also substantiates the necessity of taking into account the density of the air environment by comparison of results of tests conducted under various meteorological conditions. The method of data matching, in which there is a correction factor, is proposed and the densities are set to the value corresponding to the normal environmental conditions. Due to the lack of criteria in the normative documents for comparing two samples, set to normal conditions, it is proposed to use a statistical method - t-Student criterion. This method assumes a normal distribution of data samples, as evidenced by the results of field tests conducted earlier. Given method allows comparing the results of field tests and evaluating the quality of the current collection, not only under normal conditions, but also in the entire temperature range, relative humidity and atmospheric pressure, at which the current collector can be operated.

current collector of electric multiple unit, aerodynamic forces of current collector, aerodynamic features, air density meter, field tests of current collector, meteorological parameters of the air environment

1. Strategy of development of railway transport in the Russian Federation up to 2030. Approved by the order of Russian Federation Government on June 17, 2008, no. 877‑p. Moscow, 171 p. (in Russ.).

2. Efimov A. V., Efimov D. A., Paranin A. V. Optimizatsiya termodinamicheskikh protsessov v pare treniya “tokopriemnik — kontaktnyy provod” [Optimization of thermodynamic processes in friction pair “current collector — contact wire”]. Transport Urala [Ural region’s transport], 2013, no. 4, pp. 79 – 83.

3. GOST 32204 – 2013. Railway current collectors of electric rolling stock. General specifications. FGUP Standartinform Publ., 2013, 83 p.

4. GOST 32793 – 2014. Current collection by current collector of railway rolling stock. Nomenclature of quality indicators and methods of its determination. FGUP Standartinform Publ., 2015, 15 p.

5. Smerdin A. N., Chepurko A. E., Gorunov V. N. Sovershenstvovanie metodik laboratornykh i naturnykh ispytaniy tokopriemnika za schet kontrolya [Improving laboratory methods and field tests by controlling current collector]. Izvestiya Transsiba, 2014, no. 4, pp. 46 – 54.

6. Smerdin A. N., Golubkov A. S., Kapralova M. A. Sovershenstvovanie aerodinamicheskoy podsistemy tokopriemnika [Improving the aerodynamic subsystem of current collector]. Izvestiya Transsiba, 2013, no. 4, pp. 40 – 45.

7. Bogdanov S. N. Kholodil’naya tekhnika. Konditsionirovanie vozdukha. Svoystva veshchestv. Spravochnik [Refrigeration equipment. Air conditioning. Properties of materials. Reference book], 4th edition, reworked and amended. Saint-Petersburg, SPb‑ GAKhPT Publ., 1999, 320 p.

8. Davis R. S. Equation for the Determination of the Density of Moist Air (1981/91), Metrologia, 1992, no. 29, pp. 67 – 70.

9. Formule pour la Determination de la Masse Volumique de 1’Air Humide, BIPM Proc.‑Verb. Com. Int. Poids et Mesures, 1981, no. 49, pp. 1 – 15.

10. Smerdin A. N., Golubkov A. S., Chepurko A. E. Recorder of aerodynamic characteristics of current collector. Utility patent of RF №143955, Otkrytiya. Izobreteniya Publ., 2014, no. 22. (in Russ.).

11. Garbuzov V. M., Ermakov A. L., Kublanov M. S., Tsipenko V. G. Aeromekhanika. Uchebnik dlya studentov vuzov [Aeromechanics. Textbook for college students]. Moscow, Transport Publ., 2000, 287 p.

12. GOST 8.050 – 73. Normal conditions for performing linear and angular measurements. Moscow, Izdatel’stvo standartov [Standard publ.], 1973, 19 p. (in Russ.).