Design principles of combustion manikin system

The Burning Manikin System primarily consists of a burning manikin, a data acquisition device, a flame generation and control device, a skin heat transfer model and burn assessment model, and a centralized control and application software platform. The design principle simulates the thermal exposure of a human body in a burning flame, measuring changes in the manikin's surface temperature and estimating the potential second- and third-degree burns and the percentage of total burn area. The greater the burn area percentage, the worse the garment's flame retardant performance.

Manikin Body:

Based on design requirements, after comparing and analyzing the physical properties of high-temperature-resistant materials, polyimide, currently the highest-rated material with excellent mechanical, dielectric, and corrosion resistance, was selected as the primary material for the burning manikin. Based on the manikin's appearance, the manikin model was manufactured using the following process: polyimide synthesis - curing the resin material - molds for the anatomical segments and high-temperature pressing - vacuum curing - and surface treatment.

Burning Manikin System Surface Thermal Sensor:

The manikin's surface thermal sensor senses the degree of heat exposure to the human skin during fire exposure and, as a result, predicts the potential severity of burns. Thermal sensors used abroad primarily include TPP copper sheet heat flux sensors, insulated copper sheet sensors, and embedded thermocouple sensors. Of these three types, the insulated copper sheet sensor is the most reliable.

Experiments have shown that the insulated copper sheet sensor, similar to the TPP copper sheet heat flux sensor, offers stable readings, rapid response, a wide range, and good repeatability. Furthermore, the sensor is smaller than the TPP sensor, occupying significantly less space and mass. In high-temperature environments, the average response speed of the embedded thermocouple sensor is slower than that of the insulated copper sheet sensor. Therefore, the research team developed an insulated copper sheet sensor with a diameter of 1 cm and a thickness of 0.16 cm. Using a brazing process, the copper sheet is connected to a K-type thermocouple with a wire diameter of 0.2 mm, achieving a measurement accuracy of 0.2°C.

Sensor Placement:

Taking into account factors such as the manikin area, data collection, and burn assessment calculation, 120 insulated copper sheet sensors were evenly distributed across the manikin surface. When installing the sensors, a milling cutter was used to drill holes according to the diameter and depth of the copper sheet to ensure a close fit between the sensor surface and the test dummy, ensuring even sensor distribution.

Data Acquisition Device:

The data acquisition device primarily collects and processes temperature signals from 120 thermocouples on the dummy's surface. To ensure synchronous and high-speed acquisition of 120 temperature signals, 20 data acquisition and processing units were designed. Each data acquisition and processing unit consists of a main control CPU, AD acquisition circuit, real-time clock circuit, power supply circuit, and thermocouple temperature sensors.

Flame Generation and Control Device:

The flame generation and control device primarily generates the combustion flame required for testing the flame retardant performance of clothing. It comprises three components: fuel selection, gas pipeline design, and burner.

Fuel Selection:

After comparing and analyzing the physical and chemical properties of commonly used clean, combustible gases, propane was selected as the fuel for the test system. Propane is widely available and forms water vapor and carbon dioxide upon combustion. It is an environmentally friendly fuel with a high calorific value, a low boiling point, and good safety, making it suitable for use in colder northern laboratories.