ON THE PARAMETERS OF MOVEMENT OF A FREIGHT TRAIN WHEN STOPPINGS ON A FLAT SECTION OF THE RAILWAY

ABSTRACT

The results of the substantiation of the dynamics of the kinematic parameters of the movement of freight trains on a virtual flat section of the railway, organized by electric locomotives 3VL80^S at stops at the intermediate and terminal stations, are presented. The obtained kinematic parameters of the stopping process of a freight train of various train masses and the regression equations for determining the above-mentioned parameters on virtual and identical real railway sections constitute the practical significance of research and are recommended for implementation in the operation of the locomotive complex enterprises.

АННОТАЦИЯ

Представлены результаты обоснования динамики кинематических параметров движения грузовых поездов на виртуальном равнинном участке железной дороги, организованном электровозами 3ВЛ80^С при остановках на промежуточной и конечной станции. Полученные кинематические параметры остановочного процесса грузового поезда различной массы состава и уравнения регрессии для определения упомянутых выше параметров на виртуальных и, идентичных им, реальных участках железных дорог составляют практическую значимость исследований и рекомендуются для внедрения в работу предприятий локомотивного комплекса.

Keywords: research, result, freight train, electric locomotive, railway track, parameter, siding, analysis, station, time, speed, flat, virtual.

Ключевые слова: исследование, результат, грузовой поезд, электровоз, железная дорога, параметр, разъезд, анализ, станция, время, скорость, равнинный, виртуальный.

Introduction

At the moment, on the railway of Uzbekistan, as well as throughout the world, there is a problem of saving fuel resources. This problem is relevant for both electric and diesel rolling stock.

The experience of previous studies on optimizing the transportation work of locomotives [1] shows that fuel consumption increases with an increase in the mass of the rolling stock, and when it stops. Analysis and evaluation of the efficiency of operation of the 3VL80S electric locomotive on the flat section of the railway [2-4] confirm the above.

According to the methods developed by the authors, analytical and graphical studies, there are already calculations of the kinematic parameters of the movement of freight trains on some sections of the railway of Uzbekistan [4,5]. The considered kinematic parameters of movement include: the path of deceleration and acceleration, and the speed of movement during braking and acceleration [4]. One of the authors of the article conducted research on the dependence of changes in fuel consumption with an increase in the mass of the rolling stock [5]. The calculations were made for a freight train 3VL80^S on a flat section of the Uzbek railway. In these works, the time of the train to accelerate and decelerate is not taken into account.

The task of the research in this article is to consider the kinematic parameters of freight trains at stops at railway sections of Uzbekistan of various complexity. The results obtained are of practical interest for specialists in the locomotive complex of the railway.

Problem statement and research methods

The purpose of the research is to calculate the kinematic parameters of a freight electric locomotive of the 3VL80^S series, in a more accurate approximation to real conditions. The calculated parameter is the speed of the rolling stock during its braking and acceleration at intermediate stations. 

The object and subject of research is the material and technological organization of freight traffic on straight sections of the railway. The object of study is a straightened track profile, the first type, and freight electric locomotives of the 3VL80^S series, with different weights. The subject of the study is the kinematic parameters of the movement of a freight train, taking into account the analysis of braking and acceleration at stations.

Traction calculations were carried out according to an already existing algorithm [2-4], methods and methods [6], developed by one of the authors of the article. Using the operating manual [7], the author of the studies [2-4] describes the design features, technical parameters, energy and performance indicators of the 3VL80^S electric locomotive and the characteristics of the straight section of the railway track.

Research results and their analysis

An analysis of the movement of freight trains with different masses [2-4] suggests that the transportation of goods occurs at a uniform speed. Speed fluctuations do not exceed the allowable interval ΔV = 10 km/h.

The actual values of the speed and time of movement of a freight train, taking into account its stops at intermediate and final stations, are given in Table 1.

Kinematic parameters of electric locomotive 3VL80^S during braking and acceleration at intermediate and end stations are shown in Figure 1.

In Table 1 and Figure 1, the following designations are accepted:

Vз' and Vз'' – the speed of the freight train at the beginning of braking, respectively, at the intermediate and final stations;

Vр' is the speed of the freight train at the moment of "surge" of the train's non-stop running at the intermediate station;

∆tз' and ∆tз'' – freight train deceleration time, respectively, at the intermediate and final stations in case of freight train braking;

∆tр' – acceleration time of a freight train at an intermediate station when starting off;

Sз' and Sз'' – a way of deceleration of a freight train, respectively, at an intermediate and final station in case of braking of a freight train;

Sp' is the acceleration path of a freight train at an intermediate station when starting off.

For clarity, in Figure 1, the deceleration time ∆tз' and the acceleration time ∆tр' of a freight train, when it is braked at an intermediate station, are reduced by 1.5 times and 2.0 times, respectively.

Table 1.

Kinematic parameters of movement, electric locomotive 3VL80^S, during braking and acceleration, at the intermediate and final station

Analysis of the research results (Table 1, Fig. 1), they say that an increase in the mass of a freight train, during braking (the speed Vр', Vз', Vз'' decreases), at the intermediate and final stations, lead to an increase in:

• time ∆tз', ∆tз'' braking;
• acceleration time ∆tр';
• ways Sz', Sz'' braking;
• acceleration path Sp'.

Figure 1. Kinematic parameters of the stopping process of a freight train at the intermediate and final station, electric locomotive 3VL80^S

The dynamics of changes in kinematic parameters in terms of travel time, travel path and speed of movement of the stopping process of a freight train in the range of the train mass differentiation interval accepted by us from Q₁ = 2500 t to Q₃ = 3500 t by ∆Q = 500 t is described by the following regression equations.

Deceleration time ∆tз' of a freight train when braking at an intermediate station, min

∆tз' = 0.125Q_i² – 0.425Q_i + 2.1                             R²=1.0                           (1)

Deceleration time ∆tз'' of a freight train when braking at the end station, min

∆tз'' = 0.05Q_i² – 0.05Q_i + 1.4                                R²=1.0                           (2)

Acceleration time ∆tр' when starting a freight train at an intermediate station, min

∆tр' = – 0.15Q_i² + 0.85Q_i + 0.7                                 R²=1.0                          (3)

Sz' deceleration path of a freight train when braking at an intermediate station, km

Sz' = 0.075Q_i² – 0.175Q_i + 2.45                                    R²=1.0                          (4)

Deceleration path Sз'' of a freight train when braking at the end station, km

Sz'' = 0.1Q_i² – 0.2 Q_i + 2.25                                R²=1.0                                (5)

Acceleration path Sp' when starting a freight train at an intermediate station, km

Sp' = - 0.1Q_i² + 0.55Q_i + 2.5                                R²=1.0                                   (6)

Speed Vз' at the beginning of braking of a freight train at an intermediate station, km/h

Vз' = – 2Qi + 98                                               R²=1.0                                  (7)

Speed Vз'' at the beginning of the braking of a freight train at the end station, km/h

Vз'' = – 0.5Q_i² + 0.5Qi +98                                 R²=1.0                                    (8)

Speed Vp' at the end of the acceleration of a freight train at an intermediate station, km/h

Vр' = 0.5Q_i² – 6Q_i + 104                               R²=1.0                                      (9)

In formulas (1) - (9), the approximation reliability value is R² = 1.0. The necessary condition for reliability is R²≥0.8. The value Q_i = 1,2,3 denotes traction calculation options.

It can be seen from the regression equations that the dynamics of kinematic parameters, in relation to the change in the mass of a freight train, is described by a polynomial of the second degree. An exception is the speed of movement Vз' at the beginning of braking, a freight train, at an intermediate station.

Conclusion

The authors of the article derived the kinematic parameters of the movement of freight trains and electric locomotives 3VL80^S. The calculation results are presented in the form of tables and graphs.  The authors obtained regression equations for determining the main kinematic parameters of the transportation work of electric traction locomotives. In the calculations, the authors took into account the braking process on real, straight sections of the railway.

The kinematic parameters obtained in the article can be used in the operation of the locomotive depot of Uzbekistan, during the operation of three sectional freight electric locomotives of the 3VL80^S series, on straight sections of the track.

Reference:

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