Flow-limiting valve for racing car

Abstract

The utility model belongs to the technical field of racing cars, and particularly relates to a flow-limiting valve for racing cars, which comprises a valve body, concave pits are distributed in the valve body, the concave pits are hemispherical, the concave pits are divided into four areas from an inlet direction to an outlet direction according to the axial length position, the area between 0mm and 43mm is an area A1, the area between 43mm and 67.5 mm is an area A2, and the area A2 is an area A3. The area between 67.5 mm and 110 mm is an A3 area, and the area between 110 mm and 170 mm is an A4 area. The pits are added on the basis of the smooth inner wall of the valve body, so that flow loss caused by the action of fluid and the inner wall is reduced, fluid boundary layer separation is weakened, turbulent flow resistance is reduced, the problem of non-uniform pressure caused by airflow turbulence in a follow-up pressure stabilizing cavity is further solved, the air inlet efficiency and response of an engine are improved finally, and the service life of the engine is prolonged. The torque platform extends.

Description

Technical Field

[0001] This utility model belongs to the field of racing technology, specifically relating to a flow limiting valve for racing cars. Background Technology

[0002] The Formula Student China (FSC) is a car design and manufacturing competition for university students majoring in automotive engineering or related fields. Each participating team is required to design and manufacture a race car capable of completing all or part of the events within one year, according to the rules and standards. The Wuhan University of Technology (WUT) Formula Fuel Racing Team has been a mainstay of the FSC since its inception, achieving excellent results at the Shanghai International Circuit. With recent changes to engine displacement regulations, the KTM 690 has become a popular engine choice for many teams, and the WUT team switched to a KTM 690 engine for the 2021 season. However, due to current restrictions on flow restrictors, teams struggle to fully utilize the engine's capabilities. Most teams opt for turbocharging to compensate for this, but this adds significant weight. Current research on flow restrictors largely focuses on optimizing valve length and the inlet / outlet widening angle. Within the existing technical framework of traditional flow restrictors, significant technical bottlenecks remain in their structural design and flow control methods, specifically manifested in insufficient ability to regulate the complex flow field characteristics within the intake system. When a fluid medium flows through a flow-limiting device, the interaction between the fluid kinetic energy and the wall shear stress, constrained by the rigid structure of the traditional throttling valve and the fixed opening adjustment method, induces a significant turbulent boundary layer effect. This effect not only leads to a sharp increase in the local velocity gradient, generating an additional 15-30% of turbulence drag loss, but more importantly, it induces boundary layer uncertainty separation under Reynolds number Re>5×10^5 conditions. This phenomenon manifests as unsteady pulsations at the flow separation point (fluctuation amplitude can reach ±12% of the design operating point), directly causing the following technical defects: 1) The random shedding of the separated eddies causes the system pressure pulsation coefficient to exceed 0.25, seriously affecting the intake stability; 2) The uncontrollable development of the secondary flow structure significantly increases the total pressure loss coefficient (typically reaching 0.8-1.2); 3) The turbulence intensity increases to 20%-40%, exacerbating kinetic energy dissipation and reducing the system's isentropic efficiency by about 5-8 percentage points. More seriously, this flow instability phenomenon exhibits a significant Mach number dependence. Under Ma>0.3 conditions, it leads to a complex flow problem involving shock waves and boundary layer disturbances, further amplifying flow losses and generating broadband pressure oscillations (frequency range up to 50-500Hz). Existing passive flow control schemes based on empirical formulas struggle to achieve real-time dynamic compensation of the flow field, resulting in traditional flow restrictors generally achieving flow control accuracy below the design requirement of ±5% under unsteady-state conditions. Utility Model Content

[0003] This invention provides a flow limiting valve for racing cars to address the aforementioned problems.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A flow control valve for racing cars includes a valve body with recesses distributed within the valve body.

[0006] Furthermore, the pit is arranged in four regions according to its axial length from the inlet to the outlet: region A1 is between 0mm and 43mm, region A2 is between 43mm and 67.5mm, region A3 is between 67.5mm and 110mm, and region A4 is between 110mm and 170mm.

[0007] Furthermore, the pits are evenly distributed in each region. 400 pits are evenly distributed in region A1, 200 pits are evenly distributed in region A2, 182 pits are evenly distributed in region A3, and 375 pits are evenly distributed in region A4.

[0008] Furthermore, the depth of the pit in region A1 is 0.75 mm, the depth of the pit in region A2 is 0.6 mm, the depth of the pit in region A3 is 0.5 mm, and the depth of the pit in region A4 is 0.75 mm.

[0009] Furthermore, the pit is hemispherical.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] This invention divides the flow restrictor valve into four fluid sections along its axial direction. Through simulation calculations, the depth and density of the pits in each section are designed and matched. By adding pits with a depth of 0.5-0.75mm to the smooth inner wall of the flow restrictor valve, the flow loss caused by gas-solid friction between the fluid and the inner surface of the flow restrictor valve is reduced. This also weakens the fluid boundary layer separation problem, reduces the total average turbulence intensity and turbulence resistance in the fluid domain, and further reduces the pressure unevenness caused by airflow turbulence in the pressure stabilizing chamber behind the flow restrictor valve. This enhances the consistency and uniformity of the intake airflow in a single-cylinder engine, increases the average flow velocity of the intake system, and ensures better oil-air mixing. Ultimately, this results in improved output power and response in the mid-to-high speed range of the engine, and an extended torque plateau. Attached Figure Description

[0012] Figure 1 This is a front view of the present invention;

[0013] Figure 2 This is a cross-sectional view of the present invention;

[0014] Figure 3 The image shows the actual vehicle running log of a traditional flow restrictor valve.

[0015] Figure 4 This is a real vehicle running log diagram of the flow limiting valve of this utility model;

[0016] Figure 5 Velocity contour plot of a traditional flow limiting valve;

[0017] Figure 6 This is a velocity cloud diagram of the flow limiting valve of this utility model;

[0018] Figure 7 Pressure cloud diagram of a traditional flow restrictor valve;

[0019] Figure 8 This is a pressure cloud diagram of the flow limiting valve of this utility model;

[0020] Figure 9 A comparison diagram of engine bench test torque between a traditional flow limiting valve and the flow limiting valve of this utility model;

[0021] Figure 10 The flow field diagram is for a traditional flow restrictor valve.

[0022] Figure 11 The flow field diagram is shown for the flow limiting valve of this utility model.

[0023] Figure 12 This is a schematic diagram of the fluid flow direction in the recess of this utility model;

[0024] In the diagram, valve body 1 and recess 2 are shown. Detailed Implementation

[0025] To further illustrate the technical solution of this utility model, the following embodiments will be used to further explain this utility model.

[0026] like Figure 1 and Figure 2As shown, a flow restrictor valve for racing cars includes a valve body 1. Recesses 2 are distributed within the valve body 1, each recess 2 being hemispherical. The recesses 2 are arranged in four regions along their axial length from the inlet to the outlet: region A1 (0mm to 43mm), region A2 (43mm to 67.5mm), region A3 (67.5mm to 110mm), and region A4 (110mm to 170mm). The recesses 2 are evenly distributed within each region. 400 recesses 2 are evenly distributed within region A1, 200 within region A2, 182 within region A3, and 375 within region A4. The number of pits 2 on different cross sections within a single region is the same. The depth of pit 2 in region A1 is 0.75 mm, the depth of pit 2 in region A2 is 0.6 mm, the depth of pit 2 in region A3 is 0.5 mm, and the depth of pit 2 in region A4 is 0.75 mm.

[0027] like Figure 3 and Figure 4 As shown, the intake pressure of a traditional flow restrictor valve is 93.8 kPa under the condition of engine speed of 6480.5 rpm and throttle opening of 93.4%, while the intake pressure of the flow restrictor valve of this utility model is 95.0 kPa under the same conditions, which is an improvement of 1.7%.

[0028] like Figure 5 and Figure 6 As shown, the velocity gradient change of the traditional flow restrictor valve is larger than that of the flow restrictor valve of this invention when the air inlet velocity is 15m / s, and the uniformity of airflow velocity is poor.

[0029] like Figure 7 and Figure 8 As shown, the uniformity of fluid pressure distribution in a traditional flow restrictor is worse than that of the flow restrictor of this invention when the air inlet velocity is 15 m / s, which can easily cause turbulence and flow outside the acceptable range.

[0030] like Figure 9 As shown, under the same test conditions, based on engine bench testing, the external characteristic curves of the engine equipped with the flow limiting valve of this utility model are all above those of the engine equipped with the conventional flow limiting valve.

[0031] like Figure 10 and Figure 11 As shown, under the same intake conditions, the gas flow rate of the flow limiting valve of this utility model is higher than that of the traditional flow limiting valve, and the flow rate uniformity in the middle section is better.

[0032] The design principle of the recessed area on the inner wall of the valve body: In fluid dynamics, the viscosity of gas causes the airflow to flow tightly against the inner wall of the valve body. When there is no recessed area on the inner wall of the valve body, the main interaction between the gas and the solid wall is gas-solid friction. However, when the recessed structure is present, the airflow flows over the leading edge of the recess... Figure 12 Significant changes will occur in region B / C: as the airflow direction is forced to change and collides with the surface of the pit, some kinetic energy is dissipated in the process, resulting in a decrease in local flow velocity.

[0033] At the rear edge of the pit Figure 12 In region E, the gas pressure difference drives part of the airflow into the pit. Simultaneously, the front of the pit... Figure 12 The vortex overflow effect in region A causes a drop in internal pressure, and this pressure differential distribution promotes a stable gas circulation within the pit. This circulation system improves flow characteristics through the following mechanisms: 1) The low-speed fluid accumulated inside the pit forms a vortex "air cushion," effectively isolating the wall surface from direct contact with the high-speed mainstream, thereby reducing frictional resistance; 2) The mainstream velocity above the pit is significantly higher than the fluid velocity on the adjacent flat surface, and this velocity gradient induces the low-speed fluid inside the pit to rotate along the flow direction; 3) The kinetic energy transfer effect of the rotating fluid accelerates the mainstream flowing across the pit surface, ultimately achieving optimized regulation of the pressure distribution and velocity field inside the flow-limiting valve.

[0034] The foregoing has shown and described the main features and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model.

[0035] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A flow limiting valve for racing cars, comprising a valve body (1), characterized in that: The valve body (1) is provided with recesses (2). The recesses (2) are arranged in four regions according to their axial length from the inlet direction to the outlet direction. The region between 0 mm and 43 mm is region A1, the region between 43 mm and 67.5 mm is region A2, the region between 67.5 mm and 110 mm is region A3, and the region between 110 mm and 170 mm is region A4.

2. The flow limiting valve for racing cars according to claim 1, characterized in that: The pits (2) are evenly distributed in each region. 400 pits (2) are evenly distributed in region A1, 200 pits (2) are evenly distributed in region A2, 182 pits (2) are evenly distributed in region A3, and 375 pits (2) are evenly distributed in region A4.

3. A flow limiting valve for racing cars according to claim 1, characterized in that: The depth of the pit (2) in region A1 is 0.75 mm, the depth of the pit (2) in region A2 is 0.6 mm, the depth of the pit (2) in region A3 is 0.5 mm, and the depth of the pit (2) in region A4 is 0.75 mm.

4. A flow limiting valve for racing cars according to claim 1, characterized in that: The pit (2) is hemispherical.

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