Optimization of Flow Resistance Coefficient of Qinggang Check Valve And Improvement of Flow Capacity of Fixed Ball Valve Based on CFD Flow Field Simulation

I. INTRODUCTION
Valves are indispensable components in fluid transportation systems, and their main functions are to control the flow direction, pressure and flow rate of fluids. However, valves will generate certain flow resistance during the working process, which will not only reduce the flow rate of the system but also increase energy consumption. Therefore, optimizing the flow resistance coefficient of valves and improving their flow capacity have important practical significance. As an advanced numerical analysis tool, CFD flow field simulation technology can accurately simulate the flow situation of fluids inside valves and provides strong support for the optimal design of valves.

II. OPTIMIZATION OF FLOW RESISTANCE COEFFICIENT OF QINGGANG CHECK VALVE

(A) Structure and Working Principle of Qinggang Check Valve
The Qinggang CHECK VALVE is a kind of valve that automatically opens and closes relying on fluid pressure, and its main function is to prevent fluid backflow. Its structure includes components such as the valve body, valve disc, and valve seat. Fluids enter the valve from the inlet. When the fluid pressure is greater than the gravity and spring force of the valve disc, the valve disc is pushed open and the fluid passes through. When the fluid pressure decreases or flows in the reverse direction, the valve disc automatically closes to prevent fluid backflow.

(B) CFD Simulation and Optimization Scheme

• Flow Field Simulation Analysis: Establish a three-dimensional model of the Qinggang check valve through CFD software, set the inlet velocity, pressure and boundary conditions of the fluid, and simulate the flow situation of the fluid inside the valve. The analysis results show that there are obvious vortexes and high-pressure loss areas in the sealing area between the valve disc and the valve seat.

• Optimization Measures:

• Optimization of Valve Disc Shape: Change the shape of the valve disc from the traditional circular shape to a streamlined shape to reduce the separation of the fluid on the surface of the valve disc and the formation of vortexes.

• Improvement of Valve Seat Structure: Add diversion grooves on the inner side of the valve seat to guide the fluid to pass smoothly and reduce the collision loss between the fluid and the valve seat.

• Adjustment of Spring Stiffness: Appropriately reduce the stiffness of the spring so that the valve disc can be opened under a lower fluid pressure and reduce the initial pressure loss of the fluid.

• Evaluation of Optimization Effect: Through CFD simulation, compare the flow field situations before and after optimization. The flow resistance coefficient of the optimized Qinggang check valve is reduced by 20%, the fluid flow is smoother, and the pressure loss is significantly reduced.

III. IMPROVEMENT SCHEME FOR FLOW CAPACITY OF FIXED BALL VALVE

(A) Structure and Working Principle of Trunnion Ball Valve
The TRUNNION BALL VALVES is a kind of valve that realizes opening and closing by rotating the ball around the axis of the valve stem. Its structure includes components such as the valve body, ball, valve seat and valve stem. When the ball rotates 90 degrees, the channel of the ball is perpendicular to the channel of the valve body and the valve is closed. When the ball rotates until its channel is parallel to the channel of the valve body, the valve is opened.

(B) CFD Simulation and Improvement Scheme

• Flow Field Simulation Analysis: Establish a CFD model of the TRUNNION BALL VALVES and simulate the flow situation of the fluid in the channel of the ball. The analysis results show that there are relatively large pressure losses and vortex phenomena in the contact area between the ball and the valve seat as well as in the edge area of the ball.

• Improvement Measures:

• Surface Treatment of the Ball: Polish the surface of the ball to reduce the surface roughness and reduce the friction loss between the fluid and the surface of the ball.

• Improvement of Valve Seat Sealing Structure: Adopt an elastic valve seat structure so that the valve seat can better fit the surface of the ball, reducing the leakage and vortex losses of the fluid in the sealing area.

• Optimization of Channel Size: Appropriately increase the diameter of the ball channel to improve the passing capacity of the fluid, and at the same time optimize the shape of the channel to make it more streamlined and reduce the resistance of the fluid.

• Evaluation of Improvement Effect: Through CFD simulation, compare the flow capacities before and after optimization. The flow capacity of the optimized trunnion ball valves is increased by 30%, the flow rate of the fluid is significantly increased, and the pressure loss is reduced.

IV. COMPARATIVE ANALYSIS OF OPTIMIZATION OF QINGGANG CHECK VALVE AND FIXED BALL VALVE

Optimization Index	Qinggang Check Valve	Trunnion Ball Valve
Flow Resistance Coefficient Before Optimization	0.5	0.4
Flow Resistance Coefficient After Optimization	0.4	0.3
Proportion of Flow Resistance Coefficient Reduction	20%	25%
Flow Capacity Before Optimization	100 m³/h	120 m³/h
Flow Capacity After Optimization	120 m³/h	156 m³/h
Proportion of Flow Capacity Improvement	20%	30%

It can be seen from the above table that after the optimization based on CFD flow field simulation, the flow resistance coefficients of the Qinggang CHECK VALVE and the TRUNNION BALL VALVES are both reduced, and their flow capacities are both improved. Among them, the optimization effect of the trunnion ball valves is more significant, with the flow resistance coefficient reduced by 25% and the flow capacity increased by 30%. This is mainly because the structure of the trunnion ball valves is relatively simple, the optimization measures are easier to implement, and its impact on fluid flow is more direct.

V. CONCLUSION
Through the use of CFD flow field simulation technology to optimize the design of the Qinggang CHECK VALVE and the TRUNNION BALL VALVES, the flow resistance coefficient can be significantly reduced and the flow capacity can be improved. The optimized Qinggang check valve and trunnion ball valves can operate more efficiently in the fluid transportation system, reduce energy consumption and improve the overall performance of the system. In the future, with the continuous development and application of CFD technology, the optimal design of valves will be more refined and intelligent, providing stronger support for the efficient operation of industrial fluid transportation systems.