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How much do you know about the types of thermal dummy?

Release time: 2015-10-15 15:39

The manikin is an instrument and equipment that simulates the heat exchange process between the human body and the environment. According to the heat dissipation characteristics of various parts of the human body, the manikin is generally divided into head, chest, back, upper limbs, hands, abdomen, legs and feet. The thermal dummy is a new biophysical test method gradually developed from the 1940s. It is widely used in clothing, occupational health, environment, fire protection, petroleum, traffic safety, aerospace, construction and other fields. The types of thermal dummy include:

1.Dry warm body dummy

The dry warm manikin can work in three ways: constant temperature method, variable temperature method and constant heat method. The isothermal method is to control the body surface temperature of each anatomical section of the warm dummy in a set range, so that the warm dummy enters a dynamic thermal equilibrium state in order to obtain stable experimental results. This method is used to measure the thermal resistance of clothing The temperature change method is based on the human body's thermal regulation model in a cold environment. It simulates the change of the body surface temperature of a real person in different environments. The body surface temperature in a steady state is not a set value, but a result that is as naturally balanced as a real person. The thermal resistance of the clothing, which is very similar to that measured by the constant temperature method, can be obtained. The temperature change method has a physiological evaluation significance similar to that of a real person [18]; the constant thermal method is based on the thermal resistance and environmental parameters of the clothing, and uses the set heat flow value to observe the body The difference in heat dissipation of the part, at this time, the body surface temperature gradually decreases until it stabilizes. Including static warm dummy and dynamic warm dummy.

2.Sweating warm dummy

Because the dry warm dummy can only simulate the physiological response of the human body in the non-evaporative heat dissipation range, people have developed sweaty warm dummy. The early sweating and warming dummy was covered with a layer of cotton fabric or other moisture-permeable underwear on the surface of the dummy to simulate human skin. First, spray distilled water on the simulated skin, and then put on clothes to make the dummy's average body surface. The temperature rises to a certain level. The control system records the temperature, environmental parameters, and heating power of the fake human body surface every 5 minutes, and calculates the evaporation resistance of the clothing. The test is completed before the simulated skin begins to dry. Because this process is a quasi-steady state process, usually a very short time, mainly by the operator's subjective judgment of the relatively stable evaporation resistance value as the test result, this method cannot accurately and reproducibly measure the evaporation of clothing resistance.

3. Breathing warm dummy

Breathable warm manikins are mainly used for the research of indoor working environment and the assessment of indoor air quality [34 ~ 36]. The size of the breathing warm dummy is the same as that of ordinary people. It consists of 25 heating sections. Each section is individually heated and independently controlled. The dummy can change its posture and free movement to simulate the real situation of the human body in various offices. Body dummy adopts tight-fitting style, because clothes can reduce the heat radiation between each section and the influence of indoor air temperature on the heat transfer coefficient during calibration, and clothes can reduce the thickness of the air layer between the clothes and the surface of the dummy. To minimize measurement uncertainty. The breathing warm dummy can work in three ways: ① Comfort mode, which simulates the dry heat dissipation and body surface temperature of ordinary people to maintain a comfortable state in a hot environment; ② Constant temperature mode, the body surface temperature of the dummy is 34 ° C; ③ Constant heat mode for indoor temperatures higher than

Evaluation of thermal environment at 34 ° C. Comfort mode can represent the actual temperature distribution of the human body and is widely used. The breathing manikin has an artificial lung consisting of a cylinder equipped with a piston. The piston is driven by an electric motor. The breathing rate is 10 to 12 times / minute. The breathing method can be oral or nose breathing. The lung ventilation is 6 liters / minute. The size and shape of the mouth or nose have an impact on the test results. During the test, the air exhaled at a distance of 0.01m from the upper lip or near the face is collected to study the transmission of pollutants between the human body by accurately measuring its concentration, temperature and humidity. Happening. Similarly, detecting the above parameters of the warm-up dummy's exhaled air can evaluate the indoor air quality.

4.Water-immersed body dummy

The immersable water heating dummy is based on the warm body dummy, and a waterproof sealing device is added to make the dummy waterproof. It is mainly used to test the protective function of wetsuits and water life jackets in cold environments. During the test, immerse the dummy in the water, keep the water temperature constant, record the surface temperature of the dummy's skin, the ambient temperature, and the heating power of each section, and calculate the total thermal resistance of the diving suit. At this time, the total thermal resistance includes underwear and diving Thermal resistance of clothing, water and air. The experiment proves that the total thermal resistance of the diving suit obtained by the immersion dummy is consistent with the total thermal resistance measured by a real person. Turbulence will greatly reduce the total thermal resistance of the diving suit, and the height of the water wave can also reduce the total thermal resistance of the diving suit. . The thermal resistance value measured by the immersion heating dummy can also be used to predict the endurance time of the garment in a certain environment.

5. Numeric warmth dummy

Due to the complicated manufacturing process and the high price of the artificial dummy, the experimental conditions of the dummy such as the artificial climate chamber are high, and only a few laboratories in the world have it. Ergonomic research with "virtual" dummy on a computer can save a lot of money. Recently, due to the rapid development of computer computing speed, Computational Fluid Dynamics (CFD) technology has been increasingly used in various industries, and it has become possible to use computer technology to simulate the human body. In contrast to traditional warm-body dummy, this computer-simulated dummy is called a numerical warm-body dummy. The simulation of heat and mass transfer around the dummy is achieved by solving a series of partial differential equations. If you enter specific environmental parameters and the thermal performance of clothing, the numerical warm dummy can calculate all the heat dissipation of the human body such as conduction, convection, radiation and evaporation, and predict the local temperature and heat transfer coefficient of the human body, as well as the sweat of each part. Distribution, etc. to evaluate the thermal comfort and air quality of an environment.

6, small warm body dummy

Small warm prostheses are mainly used to evaluate the thermal environment of newborns, especially low-weight infants. It generally consists of 6 heating sections, that is, the head, left upper limb, right upper limb, trunk, left lower limb, and right lower limb. Each section is individually heated and independently controlled. In order to simulate the actual situation, a small warm manikin lies flat and conserves. Inside the box, the test method is the same as that of a large heating dummy. Because the ratio of the baby's weight to the body surface area is larger than that of an adult, the dry heat dissipation of a small warm dummy is larger than that of a large warm dummy. The evaluation index of the thermal resistance is not much different from that of a large warm dummy.

7 , warm prostheses and prostheses

In recent years, domestic and foreign scholars have developed warm heads, artificial hands, and artificial feet, which are mainly used in the evaluation of helmets or headwear, gloves, and shoes and to guide product development. The prosthetic head is composed of the skull, face and neck, and the three parts are heated separately and controlled independently. In order to simulate sweating, the dummy head includes 25 sweating holes distributed on the face and skull. Distilled water in a water tank located above the dummy head is fed into the dummy head through a pipe. The amount of sweat is controlled by a separate valve, which can reach 70g / h. . The dummy can work in constant temperature and constant heat mode. The test results indicate the thermal comfort of the helmet by the degree of facial temperature drop. Warm body prosthetic hand consists of eight pieces, namely thumb, index finger, middle finger, ring finger, pinky finger, palm, back of the hand and wrist. The heat supply of each block is controlled by the computer. The warming artificial hand is placed in a small box with the wrists exposed. In actual life, the hand is always active, especially outdoors, so a certain airflow is introduced into the box. Finally, The heat transfer coefficient and local heat transfer coefficient of gloves are used to represent the thermal insulation performance of gloves. The heat transfer coefficient of the palm and back of the hand is low, the index finger, middle finger and ring finger are second, and the thumb and pinky are the highest. The warm body prosthetic foot consists of eight pieces, namely the toes, soles, heels, middle feet, ankles, lower calves, mid-calves and protective sections. To simulate sweating, the prosthetic foot includes five sweat glands, which are located on the toes, soles, ankles, insteps, and side ankles. Wear cotton socks on the prosthetic foot to allow water to distribute throughout the foot. The evaluation indexes are thermal resistance, moisture resistance and moisture permeability index. If connected to a pneumatic piston, it can also imitate human walking.

Source: Information from Burning Dummy Station

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