Key Takeaways & Executive Findings
- •• Derives cabin pressure calculation models for positive and negative pressure conditions based on one-dimensional isentropic flow theory. • Proposes a flow coefficient calibration method for high-precision and efficient calibration across varying leakage properties. • Establishes functional relationships between flow coefficient and leakage path area for circular and square cross-sections under positive/negative pressure. • Validates the theoretical model with high R² values (0.9928–0.9936) against experimental data, enabling accurate evaluation of train body airtightness.
Abstract
With increasingly stringent requirements for the airtightness of high-speed train bodies, determining appropriate airtightness levels has become critically important. To calculate the airtightness of high-speed train bodies more accurately, based on one-dimensional isentropic flow theory, this study derives cabin pressure calculation models for both positive and negative pressure conditions during static airtightness tests of high-speed train bodies. Since the flow coefficient, which is closely related to the leakage characteristics of the carriage, is influenced by multiple factors including operating pressure conditions (positive/negative), leakage path cross-sectional shape, and size, a flow coefficient calibration method is proposed to achieve high-precision and efficient calibration of the flow coefficient for trains with varying leakage properties. This method generates a series of flow coefficient values for circular and square cross-sectional shapes under both positive and negative pressure conditions across various cross-sectional areas. Furthermore, functional relationships between flow coefficient and leakage path area under positive/negative pressure are established through curve fitting. Using these functional relationships and the cabin pressure calculation model, the pressure variation curves for a static airtightness test are simulated. Specifically, for circular cross-sectional shapes, the theoretical curves under positive and negative pressure conditions exhibited R2 values of 0.9936 and 0.9931, respectively, when compared to experimental data, and for square cross-sectional shapes, the corresponding R2 values are 0.9928 and 0.9932, validating the accuracy of the proposed theoretical model. The proposed theoretical model effectively evaluates the airtightness of high-speed train bodies with varying performance levels during static airtightness tests, providing a robust theoretical reference for optimizing high-speed train airtightness design.
1. Introduction
In recent years, China's high-speed train development has been rapid, and high-speed train operating speed has been gradually increased. Although the higher operating speed brings higher transportation efficiency, the discomfort caused by the high-speed operation of high-speed trains under the pressure fluctuations is more and more obvious. Especially when the high-speed train passes through the tunnel, the tunnel pressure wave generated by the tunnel is transmitted to the carriage causing significant fluctuations in the pressure inside the carriage, and excessive pressure fluctuations can cause tinnitus or even earache and other discomfort symptoms for passengers inside the carriage.
Pressure changes in the carriage with the carriage airtightness and the pressure difference between inside and outside the carriage. The higher the airtightness of the carriage, the stronger the ability to maintain stable pressure inside the car. Since there are many forms of gas leakage paths in the carriage, such as the welded seams of the carriage, door seams, window seals and air conditioning system, significant air pressure fluctuations outside the carriage will be transmitted into the carriage through the leakage paths, which will ultimately lead to significant changes in the pressure inside the carriage. Nowadays, the pressure fluctuation inside the high-speed train is more and more important to the comfort of passengers, and the requirements for the airtightness of the high-speed train body are getting higher and higher [1−5].
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XIANG Xin-hua, CHEN Chun-jun, XIA Yu-tao (2025). Theoretical calculation and numerical simulation of different static airtightness of trains. Journal of Central South University. https://doi.org/10.1007/s11771-025-6147-4
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Frequently Asked Questions
What is the main objective of this study?
The study aims to accurately calculate the airtightness of high-speed train bodies by deriving cabin pressure calculation models for positive and negative pressure conditions during static airtightness tests, and to propose a flow coefficient calibration method for varying leakage properties.
How is the flow coefficient calibrated in this research?
The flow coefficient is calibrated using a proposed method that generates a series of values for circular and square cross-sectional shapes under both positive and negative pressure conditions across various cross-sectional areas, followed by curve fitting to establish functional relationships with leakage path area.
What are the key findings of the study?
The theoretical model accurately predicts pressure variation curves for static airtightness tests, with R² values ranging from 0.9928 to 0.9936 when compared to experimental data, validating its effectiveness for evaluating train body airtightness.
Why is static airtightness testing important for high-speed trains?
Static airtightness testing ensures that the train body meets operational and passenger comfort requirements by measuring the time for pressure relief under controlled conditions, which is critical for mitigating pressure fluctuations that cause discomfort.
What practical applications does this research have?
The proposed model provides a robust theoretical reference for optimizing high-speed train airtightness design, enabling engineers to evaluate and improve airtightness performance during the design phase.
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