A Design Method for Cooling Air Duct of Low-Resistance Traction Motor

Abstract

The present invention discloses a design method for a cooling air duct of a traction motor with low resistance. By using different boundary conditions, the cooling air duct of the traction motor is optimized multiple times in sequence with the optimization objectives of the minimum air duct resistance in the total air inlet section, the outlet flow rate in the long air outlet section, the same air output in the long air outlet section and the short air outlet section, the minimum resistance in the long air outlet section, and the same air output in the long air outlet section and the short air outlet section, respectively, for the total air inlet section, the long air outlet section, the short air outlet section, the long air outlet section, and the overall cooling air duct of the traction motor, so as to obtain the final optimized model of the cooling air duct of the traction motor. The design method for the cooling air duct of the traction motor with low resistance disclosed by the present invention fully considers the influence of the air outlet speed distribution of the cooling fan of the traction motor and the air duct resistance inside the traction motor on the air duct, minimizes the air duct resistance, and equalizes the flow rates at both ends of the outlet, ultimately reducing the requirements for the air volume and static pressure of the cooling fan of the traction motor and achieving the effects of energy conservation and noise reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit vehicles, and particularly to a design method for a low-resistance cooling air duct of a traction motor. Background Art

[0002] A traction motor is a key component of a locomotive and a motor car. During operation, a large amount of heat is generated inside the traction motor. To prevent the traction motor from overheating and being damaged, a ventilator needs to be equipped to force-cool the traction motor. A traction motor cooling fan is such a ventilator that provides a cooling air source for the traction motor. Considering the safety of vehicle operation, a redundant design is adopted. At least two traction motors need to be configured for one car. Therefore, one traction motor cooling fan needs to provide cooling air for two traction motors simultaneously. The two traction motors are installed at different positions under the car. They need to take air from the traction motor cooling fan through a common channel and then send it to the air inlets of the internal air ducts of the two traction motors respectively for cooling. This channel is the traction motor cooling air duct. The traction motor cooling fan, the traction motor cooling air duct, and the traction motor constitute a complete traction system, ensuring the normal operation of the locomotive and the motor car.

[0003] The air volume of the traction motor cooling fan is determined by the total air volume required by the supplied traction motors. The static pressure provided by the fan is used to overcome the resistance of the traction motor cooling air duct, the internal cooling air duct of the traction motor, the negative pressure of the inlet filter, the negative pressure of the passing wind, etc. Among them, the design of the traction motor cooling air duct is crucial. On the one hand, it will increase the demand for the static pressure of the fan, bringing problems such as high noise and high energy consumption. On the other hand, it plays a key role in the distribution of the cooling air volume. A bad design will cause a large difference in the air volume on both sides. Therefore, it is necessary to increase the total air volume to ensure that the minimum air volume can meet the demand for the cooling air of the traction motor. Due to the special position of the traction motor and various crossbeams and avoidance objects under the car, the shape of the air duct is strange and cannot adopt a conventional design. Moreover, the existing designs of the traction motor cooling air duct cannot meet the above requirements. Summary of the Invention

[0004] The present invention proposes a design method for a low-resistance cooling air duct of a traction motor for the above problems.

[0005] The technical means adopted by the present invention are as follows:

[0006] A design method for a low-resistance cooling air duct of a traction motor, the traction motor cooling air duct includes a total air inlet section, a long air outlet section, and a short air outlet section. The air inlet of the total air inlet section is connected to the outlet of the traction motor fan. The air outlet of the total air inlet section is connected to the air inlets of the long air outlet section and the short air outlet section. The air outlets of the long air outlet section and the short air outlet section are respectively connected to two traction motors, and the method includes the following steps:

[0007] Step 1: Construct a traction motor cooling air duct model according to the installation positions of the traction motor fan and two traction motors and the car body structure layout;

[0008] Step 2: Obtain the three-direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors; obtain the static pressure values at the inlet of the internal cooling air duct of the traction motor under different air volumes, and obtain the quadratic function of the static pressure and the air volume according to the air volume and the static pressure value;

[0009] Step 3: Take the three-direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors as the inlet boundary conditions for optimizing the traction motor cooling air duct model, and take the quadratic function of the static pressure and the air volume as the outlet boundary conditions for optimizing the traction motor cooling air duct model. Optimize the total inlet air section with the minimum air duct resistance of the total inlet air section as the optimization goal to obtain the first optimized model of the traction motor cooling air duct;

[0010] Step 4: Take the outlet flow rate of the long outlet air section as the optimization goal, and optimize the long outlet air section of the first optimized model of the traction motor cooling air duct to obtain the second optimized model of the traction motor cooling air duct;

[0011] Step 5: Take the consistent air outlet volumes of the long outlet air section and the short outlet air section as the optimization goal, and optimize the short outlet air section of the second optimized model of the traction motor cooling air duct to obtain the third optimized model of the traction motor cooling air duct;

[0012] Step 6: Obtain the velocity vector of the cooling air at the inlet of the long outlet air section, take the velocity vector of the cooling air at the inlet of the long outlet air section as the inlet boundary condition for optimizing the long outlet air section, and optimize the long outlet air section of the third optimized model of the traction motor cooling air duct with the minimum resistance of the long outlet air section as the optimization goal to obtain the fourth optimized model of the traction motor cooling air duct;

[0013] Step 7: Take the consistent air outlet volumes of the long outlet air section and the short outlet air section as the optimization goal, and optimize the fourth optimized model of the traction motor cooling air duct to obtain the final optimized model of the traction motor cooling air duct.

[0014] Compared with the prior art, the design method of the low-resistance traction motor cooling air duct disclosed in the present invention has the following beneficial effects: This patent will propose a design method of a low-resistance traction motor cooling air duct aiming at the characteristics of the traction motor cooling air duct. This method fully considers the influence of the outlet air velocity distribution of the traction motor cooling fan and the internal air duct resistance of the traction motor on the air duct, minimizes the air duct resistance, and equalizes the outlet flow rates at both ends. Finally, it reduces the requirements for the air volume and static pressure of the traction motor cooling fan, achieving the effects of energy saving and noise reduction. Description of the Drawings

[0015] Figure 1 Flow chart of the design method of the low - resistance traction motor cooling air duct disclosed by the present invention;

[0016] Figure 2 Structural layout model diagram of the installation positions of the traction motor fan and two traction motors and the car body in the embodiment of the design method of the low - resistance traction motor cooling air duct disclosed by the present invention;

[0017] Figure 3 Model diagram of the traction motor cooling air duct constructed according to the installation positions of the traction motor fan and two traction motors and the car body structure layout in the embodiment;

[0018] Figure 4 Aerodynamic simulation model diagram of the traction motor fan in the embodiment;

[0019] Figure 5 Schematic diagram of the three - direction velocity vectors of the cooling air at the outlet of the traction motor fan obtained from the aerodynamic simulation model of the traction motor fan in the embodiment;

[0020] Figure 6 Curve fitting schematic diagram of the quadratic function of static pressure and air volume obtained according to the air volume and static pressure value;

[0021] Figure 7 Equivalent model diagram constructed during the first optimization, and corresponding parameters in the figure are set with boundary conditions;

[0022] Figure 8 For Figure 7 Partial enlarged view of the boundary condition setting of the total air inlet section in;

[0023] Figure 9 Model diagram of the air inlet of the total air inlet section before optimization;

[0024] Figure 10 Model diagram of the air inlet of the total air inlet section after optimization;

[0025] Figure 11 Model diagram of the long air outlet section before optimization;

[0026] Figure 12 Model diagram of the long air outlet section after optimization;

[0027] Figure 13 Model diagram of the short air outlet section before optimization;

[0028] Figure 14 Model diagram of the short air outlet section after optimization;

[0029] Figure 15 Model diagram during the second optimization of the long air outlet section;

[0030] Figure 16 ForFigure 15 Partial enlarged view of the air inlet of the long air outlet section;

[0031] Figure 17 It is the structural diagram of the optimized cooling air duct of the traction motor.

[0032] In the figure: 1. Traction motor fan, 2. Internal air duct of the traction motor, 3. Car body structure, 4. Total air inlet section, 5. Long air outlet section, 6. Short air outlet section. Specific implementation mode

[0033] A design method for a low-resistance cooling air duct of a traction motor, Figure 2 The shown cooling air duct of the traction motor includes a total air inlet section 4, a long air outlet section 5 and a short air outlet section 6. The air inlet of the total air inlet section 4 is connected to the outlet of the traction motor fan 1. The air outlet of the total air inlet section 4 is connected to the air inlets of the long air outlet section 5 and the short air outlet section 6. The air outlets of the long air outlet section 5 and the short air outlet section 6 are respectively connected to two internal air ducts 2 of the traction motor, and it includes the following steps. The specific process is as Figure 1 shown:

[0034] Step 1: Construct a cooling air duct model of the traction motor according to the installation positions of the traction motor fan and two traction motors and the layout of the car body structure;

[0035] Step 2: Obtain the three-direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors; obtain the static pressure values at the inlets of the internal air ducts of the traction motor under different air volumes, and obtain the quadratic function of the static pressure and the air volume according to the air volume and the static pressure value;

[0036] Step 3: Take the three-direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors as the inlet boundary conditions for optimizing the cooling air duct model of the traction motor, and take the quadratic function of the static pressure and the air volume as the outlet boundary conditions for optimizing the cooling air duct model of the traction motor. Optimize the total air inlet section with the minimum air duct resistance of the total air inlet section as the optimization goal to obtain the first optimized model of the cooling air duct of the traction motor;

[0037] Step 4: Take the outlet flow rate of the long air outlet section as the optimization goal, and optimize the long air outlet section of the first optimized model of the cooling air duct of the traction motor to obtain the second optimized model of the cooling air duct of the traction motor;

[0038] Step 5: Take the same air outlet volume of the long air outlet section and the short air outlet section as the optimization goal, and optimize the short air outlet section of the second optimized model of the cooling air duct of the traction motor to obtain the third optimized model of the cooling air duct of the traction motor;

[0039] Step 6: Obtain the velocity vector of the cooling air at the inlet of the long air outlet section, and use the velocity vector of the cooling air at the inlet of the long air outlet section as the optimized inlet boundary condition of the long air outlet section. Optimize the long air outlet section of the third optimization model of the traction motor cooling air duct with the minimum resistance of the long air outlet section as the optimization goal to obtain the fourth optimization model of the traction motor cooling air duct;

[0040] Step 7: Optimize the fourth optimization model of the traction motor cooling air duct with the consistent air volume of the long air outlet section and the short air outlet section as the optimization goal to obtain the final optimization model of the traction motor cooling air duct.

[0041] The present invention proposes a design method for a low-resistance traction motor cooling air duct in view of the characteristics of the traction motor cooling air duct. This method fully considers the influence of the air outlet speed distribution of the traction motor cooling fan and the resistance of the traction motor on the air duct, minimizes the air duct resistance, and equalizes the flow rates at both ends of the outlet. Finally, it reduces the requirements for the air volume and static pressure of the traction motor cooling fan, achieving the effects of energy conservation and noise reduction.

[0042] Embodiment 1

[0043] The following is a specific embodiment of the air duct design by the design method of the low-resistance traction motor cooling air duct disclosed in the present application, which includes the following steps:

[0044] Step 1: Construct a traction motor cooling air duct model according to the installation positions of the traction motor fan and two traction motors and the body structure layout;

[0045] Specifically, as Figure 2 shown is the structure diagram of the installation positions of the traction motor fan 1 and two traction motors (only the internal air duct 2 of the traction motor is shown in the figure) and the body structure 3 layout, Figure 3 shown is the traction motor cooling air duct model constructed according to the installation positions of the traction motor fan and two traction motors and the body structure layout.

[0046] Step 2: Obtain the three-direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volumes required by two traction motors; obtain the static pressure values at different air volumes at the outlet of the traction motor cooling air duct, and obtain the quadratic function of the static pressure and the air volume according to the air volume and the static pressure value;

[0047] Specifically, in this embodiment, the cooling air volume required for each traction motor is 1.8 kg / s, and the required air volume for two traction motors is 3.6 kg / s. According to existing design experience, considering losses and deviations, the air volume at the inlet of the air duct is taken as 4.14 kg / s. If there is a traction motor fan, this flow rate can be used as the boundary condition to calculate the vectors in three directions of the cooling air at the outlet of the traction motor fan, and then used as the inlet boundary condition of the air duct. If not, this flow rate is directly used as the inlet boundary condition of the air duct.

[0048] In this embodiment, as Figure 4 and Figure 5 shown, through pneumatic simulation (or through experimental testing), the static pressure at the inlet of the internal cooling air duct of the traction motor is obtained at different mass flow rates. The mass flow rate function is fitted by a quadratic curve for the static pressure. In this embodiment, the following quadratic function of the static pressure and the air volume is obtained according to the air volume and the static pressure value, as Figure 6 shown, the relationship between the static pressure at the inlet of a certain type of traction motor and the mass flow rate is obtained by fitting the static pressure with a quadratic curve as y = 291.5x^2 + 162.9x - 1.825, where y is the static pressure at the motor inlet and x is the mass flow rate. This equation will be used as the outlet pressure boundary condition of the air duct.

[0049] Step 3: Use the three-direction velocity vectors of the cooling air at the outlet of the induced motor fan / the air volume required by two traction motors as the inlet boundary conditions for optimizing the traction motor cooling air duct model, and use the quadratic function of the static pressure and the air volume as the outlet boundary condition for optimizing the traction motor cooling air duct model. Optimize the total inlet air section with the minimum air duct resistance of the total inlet air section as the optimization goal to obtain the first optimized model of the traction motor cooling air duct;

[0050] Specifically, use the outlet velocity field of the ventilator as the inlet boundary condition of the air duct, and apply the relationship between the static pressure and the mass flow rate at the inlet of the internal cooling air duct of the traction motor as the outlet boundary condition to the air duct. The calculated air duct is equivalent to being equipped with a traction motor ventilator and a traction motor, but the calculation scale will be greatly reduced. The constructed model is as Figure 7 and Figure 8 shown.

[0051] If there is no traction motor fan model, a flow boundary condition can also be used for substitution. At this time, a section of length needs to be added at the inlet.

[0052] After completing the above air duct modeling, optimize the inlet section of the air duct with the total inlet pressure - total outlet pressure as the optimization goal (the minimum air duct resistance of the total inlet air section) to complete the first optimization. In this air duct optimization, the air duct resistance is reduced from the original 1292 Pa to 1081 Pa. The structures of the air duct inlet model before and after optimization are as Figure 9 and Figure 10 shown.

[0053] Step 4: Optimize the long outlet section of the first optimized model of the traction motor cooling air duct with the outlet flow rate of the long outlet section as the optimization goal to obtain the second optimized model of the traction motor cooling air duct;

[0054] Specifically, with the maximum outlet flow rate of the long air outlet section as the optimization objective, the long air outlet section is optimized. During the optimization, attention is paid to the positions where the flow in the flow channel is not smooth, and air guiding plates are added at the non-smooth positions for flow guiding to reduce the air duct resistance. At this time, it is reflected that due to the reduction of the long air duct resistance, the outlet air volume of the long air duct increases from the original 2.45 kg / s to 2.58 kg / s. The models before and after the optimization of the long air duct are as shown in Figure 11 and Figure 12 shown.

[0055] Step 5: With the same air outlet volume of the long air outlet section and the short air outlet section as the optimization objective, the short air outlet section of the second optimized model of the traction motor cooling air duct is optimized to obtain the third optimized model of the traction motor cooling air duct;

[0056] Specifically, on the basis of the fourth step, with the same air outlet volume of the long air duct and the short air duct as the optimization objective, the short air duct is optimized. After the modification, the outlet flow rates of the long and short air ducts are basically the same. The models before and after the optimization of the short air duct are as shown in Figure 13 and Figure 14 shown.

[0057] Step 6: Obtain the velocity vector of the cooling air at the inlet of the long air outlet section, use the velocity vector of the cooling air at the inlet of the long air outlet section as the inlet boundary condition for the optimization of the long air outlet section, and with the minimum resistance of the long air outlet section as the optimization objective, optimize the long air outlet section of the third optimized model of the traction motor cooling air duct to obtain the fourth optimized model of the traction motor cooling air duct;

[0058] Specifically, further optimize the long air duct. Cut the long air duct separately, and use the velocity vector diagram at the inlet section of the long air duct obtained in the fifth step as the inlet boundary condition of this long air duct. The outlet still uses the expression of the static pressure and flow rate of the traction motor as the outlet boundary condition, and optimize with the minimum resistance of the long air duct as the objective. The separate long air duct model is as shown in Figure 15 and Figure 16 shown.

[0059] Step 7: With the same air outlet volume of the long air outlet section and the short air outlet section as the optimization objective, optimize the fourth optimized model of the traction motor cooling air duct to obtain the final optimized model of the traction motor cooling air duct.

[0060] Specifically, the overall model is further optimized. Combine the optimized long air duct with the previous model to form a new overall model, and then conduct overall optimization. The optimization objective is that the outlet air volumes of the long air duct and the short air duct are the same.

[0061] The resistance of the finally optimized air duct is reduced from the previous 1292 Pa to 632 Pa, a reduction of 51% compared with the previous one, and the flow outlet uniformity is also improved. The finally optimized air duct structure is as shown in Figure 17 shown.

[0062] The parameter comparison of the traction motor cooling air duct before and after optimization is as follows:

[0063]

[0064]

[0065] From the above data, it can be seen that the air duct resistance after optimization is significantly reduced, from 1292 Pa before optimization to 632 Pa after optimization. The air volume at the two air duct outlets is more uniform. Before optimization, the maximum deviation between the air volume at the air duct outlet and the average flow rate reached 2.4%. After optimization, the maximum deviation between the air volume at the air duct outlet and the average flow rate is only 0.4%.

[0066] In this implementation scheme, the CFX software is used for fluid simulation analysis software, and Design Exploration's Response Surface Optimization is used as the optimization tool. Other CFD software can also be used for fluid simulation analysis, and other optimization software can be used for optimization.

[0067] As mentioned above, it is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A design method for a cooling air duct of a low - resistance traction motor. The cooling air duct of the traction motor includes a total air inlet section, a long air outlet section, and a short air outlet section. The air inlet of the total air inlet section is connected to the outlet of the traction motor fan. The air outlet of the total air inlet section is connected to the air inlets of the long air outlet section and the short air outlet section. The air outlets of the long air outlet section and the short air outlet section are respectively connected to two traction motors. It is characterized in that: It includes the following steps: Step 1: Construct a cooling air duct model of the traction motor according to the installation positions of the traction motor fan and two traction motors and the layout of the car body structure. Step 2: Obtain the three - direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors; obtain the static pressure values at the inlets of the internal cooling air ducts of the traction motors under different air volumes, and obtain the quadratic function of static pressure and air volume according to the air volume and static pressure values. Step 3: Take the three - direction velocity vectors of the cooling air at the outlet of the traction motor fan / the cooling air volume required by two traction motors as the inlet boundary conditions for optimizing the cooling air duct model of the traction motor, and take the quadratic function of static pressure and air volume as the outlet boundary conditions for optimizing the cooling air duct model of the traction motor. Optimize the total air inlet section with the minimum air duct resistance of the total air inlet section as the optimization goal to obtain the first - optimized model of the cooling air duct of the traction motor. Step 4: Take the outlet flow rate of the long air outlet section as the optimization goal, and optimize the long air outlet section of the first - optimized model of the cooling air duct of the traction motor to obtain the second - optimized model of the cooling air duct of the traction motor. Step 5: Take the same air outlet volume of the long air outlet section and the short air outlet section as the optimization goal, and optimize the short air outlet section of the second - optimized model of the cooling air duct of the traction motor to obtain the third - optimized model of the cooling air duct of the traction motor. Step 6: Obtain the velocity vector of the cooling air at the inlet of the long air outlet section, take the velocity vector of the cooling air at the inlet of the long air outlet section as the inlet boundary condition for optimizing the long air outlet section, and optimize the long air outlet section of the third - optimized model of the cooling air duct of the traction motor with the minimum resistance of the long air outlet section as the optimization goal to obtain the fourth - optimized model of the cooling air duct of the traction motor. Step 7: Take the same air outlet volume of the long air outlet section and the short air outlet section as the optimization goal, and optimize the fourth - optimized model of the cooling air duct of the traction motor to obtain the final - optimized model of the cooling air duct of the traction motor.

Images