Experiment and numerical investigation of flow-induced noise reduction of the cutoff throttle valves in the air conditioning system

The cutoff throttle valve is a crucial control element in the air conditioning system, which modifies the flow cross section by altering the spool and valve body movement to achieve throttling. However, due to the intricate internal flow path structure and throttling effect of the holes, fluid pressure decreases rapidly at the throttling orifices, leading to cavitation. This results in violent refrigerant fluid impact and strong rheological vibration, generating significant noise that not only affects valve efficiency but also potentially shortens its service life. To address this issue, this paper investigates the flow characteristics of the cutoff throttle valve in depth. The findings reveal that an increase in inlet pressure leads to a corresponding rise in the maximum fluid velocity within the valve, which exacerbates cavitation at the throttling orifice and consequently elevates noise levels. To suppress cavitation-induced noise, an optimized structural design incorporating spiral guide vanes in the downstream pipeline of the valve is proposed. Comparative simulation analysis between the original and optimized models under identical working conditions demonstrates a reduction in maximum acoustic pressure level from 92.12to 77.08 dB. The experimental data indicate that, compared to the original model, the optimized model can achieve a reduction in sound pressure level values by up to 12.4%. In conclusion, for cutoff throttle valves prone to cavitation and flow noise components, it is essential to identify key factors triggering noise through in-depth study of their flow characteristics and implement effective optimization measures to achieve noise suppression, improve valve efficiency, and extend its service life.