Amphibious aircraft airborne equipment surface condensation prediction method

Abstract

The invention discloses a method for predicting surface condensation of airborne equipment of an amphibious aircraft. The method comprises the following steps: (1) calculating absolute humidity in electrical equipment; (2) calculating saturated vapor pressure in the electrical equipment; (3) calculating the highest humidity in the electrical equipment; (4) calculating the relative humidity in the electrical equipment; and (5) calculating the dew point temperature. The method for predicting the condensation on the surface of the airborne equipment of the amphibious aircraft can be used for evaluating the influence of the corrosion environment on the condensation on the surface of the airborne equipment of the aircraft.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft environmental adaptability verification, and in particular relates to a method for predicting condensation on the surface of airborne equipment of an amphibious aircraft. Background Art

[0002] The most authoritative specifications for dew point temperature calculation include GB / T 35226-2017 "Surface Meteorological Observation Specification for Air Temperature and Humidity" ASHRAE Manual and the World Meteorological Organization's Guide to Climate Observation (WMO). However, the actual wetting phenomenon is more complicated. The wetting of solid surfaces is affected by factors such as solid material properties, surface morphology, and pollutants. The dew point temperature alone cannot be used as a criterion for the occurrence of many wetting phenomena. Summary of the invention

[0003] Purpose of the Invention

[0004] In order to predict condensation on the surface of aircraft onboard equipment in a corrosive environment, the present invention provides a method for predicting condensation on the surface of amphibious aircraft onboard equipment.

[0005] Inventing technical solutions

[0006] A method for predicting condensation on the surface of airborne equipment of an amphibious aircraft comprises the following steps:

[0007] (1) Calculate the absolute humidity inside the electrical equipment;

[0008] (2) Calculate the saturated vapor pressure inside electrical equipment;

[0009] (3) Calculate the maximum humidity inside the electrical equipment;

[0010] (4) Calculate the relative humidity inside electrical equipment;

[0011] (5) Calculate the dew point temperature.

[0012] Preferably, the calculation formula for absolute humidity in step (1) is:

[0013]

[0014] Where a is the absolute humidity of the environment, e is the vapor pressure, Rω is the gas constant of water vapor, T is the temperature, m is the mass of water vapor contained in the air, and V is the volume of the air.

[0015] Preferably, the saturated vapor pressure in step (2) is calculated using the Goff-Grech formula.

[0016] Preferably, the calculation formula of saturated vapor pressure is:

[0017]

[0018] In the formula, E is the saturated vapor pressure, m and n are related factors; T is the temperature, and t is the temperature.

[0019] Preferably, for the conversion between Kelvin temperature T and Celsius temperature t, the conversion method is shown in formula (3):

[0020] T = (t + 273.15)·K (3).

[0021] Preferably, the calculation formula for the maximum humidity in step (3) is:

[0022]

[0023] In the formula, a max is the absolute humidity under saturated state, E is the saturated vapor pressure, Rω is the gas constant of water vapor, and T is the temperature.

[0024] Preferably, the calculation formula for relative humidity in step (4) is:

[0025]

[0026] In the formula, a is the absolute humidity of the environment, a max is the absolute humidity under saturated state, e is the vapor pressure, and E is the saturated vapor pressure.

[0027] Preferably, the dew point temperature in step (5) can be calculated by the following formula:

[0028]

[0029] In the formula, Td is the dew point temperature, T is the current ambient temperature, is the saturated vapor pressure corresponding to the dew point temperature, E T is the saturated vapor pressure at the current ambient temperature, and RH is the current ambient relative humidity.

[0030] Advantages of the present invention: The method for predicting condensation on the surface of amphibious aircraft airborne equipment determined by the present invention can be used to evaluate the impact of a corrosive environment on condensation on the surface of aircraft airborne equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the temperature-relative humidity-absolute humidity relationship diagram. DETAILED DESCRIPTION

[0032] The present invention is achieved through the following technical solutions.

[0033] A method for predicting condensation on the surface of amphibious aircraft equipment is proposed. The theoretical mechanism and occurrence conditions of low-temperature condensation in the condensation phase change process are analyzed:

[0034] Electrical equipment serving in a hot, humid, high-salt, and changeable marine climate environment is affected by working conditions and external climate conditions. The microenvironment changes inside the equipment vary greatly, and condensation and other wetting phenomena are very likely to occur. When the surface temperature of objects inside electrical equipment is lower than the dew point of the surrounding air, water vapor atomizes when it is cooled or condenses into a liquid phase on the surface of the object, which is low-temperature condensation. The conditions for condensation mainly depend on the ambient air temperature and humidity and the solid surface temperature. The water vapor carrying limit of air at different temperatures is different, and the water vapor content in the air, that is, the absolute humidity (AH: Absolute Humidity), determines the dew point temperature.

[0035] Step 1: Calculate absolute humidity. Absolute humidity refers to the mass of water vapor contained in a unit volume of air. The calculation formula for absolute humidity (a / kg·m-3) is:

[0036]

[0037] Where:

[0038] a——absolute humidity of the environment, in kilograms per cubic meter (kg·m-3);

[0039] e——vapor pressure, in Pascals (Pa);

[0040] Rω——gas constant of water vapor (461.52 J·kg-1·K-1);

[0041] T——temperature, in Kelvin (K);

[0042] m——The mass of water vapor contained in the air, in kilograms (kg);

[0043] V – volume of air, in cubic meters (m3).

[0044] Step 2: Calculate the saturated vapor pressure. The saturated vapor pressure (E / Pa) of air at different ambient temperatures can be calculated using the Goff-Gratch formula recommended by the World Meteorological Organization (WMO), which can be expressed as follows:

[0045]

[0046] Where:

[0047] E——saturated vapor pressure, in Pascals (Pa);

[0048] m, n——correlation factors;

[0049] T——temperature, in degrees Kelvin (K);

[0050] t——temperature, in degrees Celsius (℃).

[0051] For the conversion between Kelvin temperature T and Celsius temperature t, the conversion method is shown in formula (3):

[0052] T=(t+273.15)·K (3)

[0053] Step 3: Calculate the maximum humidity.

[0054] There is an upper limit to the amount of water vapor that a unit volume of air can hold, which is the absolute humidity under saturation, i.e. the maximum humidity. The calculation formula for the maximum humidity (amax / kg·m-3) is:

[0055]

[0056] Where:

[0057] amax - absolute humidity at saturation, in kilograms per cubic meter (kg·m-3);

[0058] E——saturated vapor pressure, in Pascals (Pa);

[0059] Rω——gas constant of water vapor (461.52 J·kg-1·K-1);

[0060] T – temperature in degrees Kelvin (K).

[0061] Step 4: Calculate relative humidity.

[0062] Relative humidity (RH) is the ratio of absolute humidity to maximum humidity. The relative humidity of saturated air is 100%. As the temperature rises, the water vapor in the air increases. That is, with the same amount of water vapor, the relative humidity will increase when the temperature decreases; and the relative humidity will decrease when the temperature increases. Therefore, when providing relative humidity, temperature data must also be provided. The calculation formula for relative humidity is:

[0063]

[0064] Where:

[0065] a——absolute humidity of the environment, in kilograms per cubic meter (kg·m-3);

[0066] amax——absolute humidity at saturation, in kilograms per cubic meter (kg·m-3);

[0067] e——vapor pressure, in Pascals (Pa);

[0068] E——saturated vapor pressure, unit is Pa (Pa).

[0069] According to the Goff-Gratch formula, the relative humidity-absolute humidity relationship diagram is drawn as follows Figure 1 As shown, Figure 1 The effect of temperature change on relative humidity under different absolute humidity conditions under normal atmospheric pressure is shown. For more accurate values, detailed mathematical calculations can be performed using the above formula, as shown in Table 1. According to the above formulas (1) to (5), it can be used to determine the absolute humidity and relative humidity of air at a certain temperature, or to determine the dew point when the temperature drops. The dew point temperature refers to the temperature of air when it is cooled to saturated air under the condition that the absolute humidity and air pressure do not change. When the water vapor in the air reaches saturation, the air temperature is the same as the dew point temperature; when the water vapor has not reached saturation, the air temperature is higher than the dew point temperature. Therefore, the difference between the dew point temperature and the air temperature can indicate the degree of saturation of the water vapor in the air. The condensation situation inside the corresponding closed space can be accurately predicted by querying the dew point.

[0070] Table 1 Absolute humidity of air under different temperature and humidity conditions

[0071]

[0072] Step 5: Calculate the dew point temperature.

[0073] When the relative humidity is 100%, the temperature of the surrounding environment is the dew point temperature. The lower the dew point temperature is than the temperature of the surrounding environment, the less likely it is to condense, that is, the drier the air is. The dew point temperature can be calculated by the following formula:

[0074]

[0075] Where:

[0076] Td - dew point temperature, in degrees Kelvin (K);

[0077] T——Current ambient temperature, in degrees Kelvin (K);

[0078] ——The saturated vapor pressure corresponding to the dew point temperature, in Pascals (Pa);

[0079] E T ——Saturated vapor pressure at current ambient temperature, in Pascals (Pa);

[0080] RH——Relative humidity of the current environment, in percentage (%).

[0081] Therefore, by substituting the saturated vapor pressure formula (5) into the above formula, the dew point temperature can be obtained. The dew point temperature under different temperature and humidity environmental conditions is shown in Table 2.

[0082] Table 2 Dew point temperature under different temperature and humidity conditions

[0083]

[0084] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A method for predicting condensation on the surface of equipment on an amphibious aircraft, characterized in that: The steps include: (1) Calculate the absolute humidity inside the electrical equipment; (2) Calculate the saturated vapor pressure inside electrical equipment; (3) Calculate the maximum humidity inside the electrical equipment; (4) Calculate the relative humidity inside electrical equipment; (5) Calculate the dew point temperature.

2. A method for predicting condensation on the surface of amphibious aircraft airborne equipment according to claim 1, characterized in that: The calculation formula for absolute humidity in step (1) is: Where a is the absolute humidity of the environment, e is the vapor pressure, Rω is the gas constant of water vapor, T is the temperature, m is the mass of water vapor contained in the air, and V is the volume of the air.

3. The method for predicting condensation on the surface of equipment on an amphibious aircraft according to claim 1, characterized in that: In step (2), the saturated vapor pressure is calculated using the Goff-Grech formula.

4. A method for predicting condensation on the surface of equipment on an amphibious aircraft as claimed in claim 3, characterized in that: The calculation formula for saturated vapor pressure is: In the formula, E is the saturated vapor pressure, m and n are related factors; T is the temperature, and t is the temperature.

5. The method for predicting condensation on the surface of equipment on an amphibious aircraft as claimed in claim 4, characterized in that: For the conversion between Kelvin temperature T and Celsius temperature t, the conversion method is shown in formula (3): T = (t + 273.15)·K (3).

6. A method for predicting condensation on the surface of equipment on an amphibious aircraft as claimed in claim 5, characterized in that: The calculation formula for the maximum humidity in step (3) is: In the formula, a max is the absolute humidity under saturated state, E is the saturated vapor pressure, Rω is the gas constant of water vapor, and T is the temperature.

7. A method for predicting condensation on the surface of equipment on an amphibious aircraft as claimed in claim 6, characterized in that: The calculation formula for relative humidity in step (4) is: In the formula, a is the absolute humidity of the environment, a max is the absolute humidity under saturated state, e is the vapor pressure, and E is the saturated vapor pressure.

8. The method for predicting condensation on the surface of equipment on an amphibious aircraft according to claim 7, characterized in that: Step (5) The dew point temperature can be calculated by the following formula: In the formula, Td is the dew point temperature, T is the current ambient temperature, is the saturated vapor pressure corresponding to the dew point temperature, E T is the saturated vapor pressure at the current ambient temperature, and RH is the current ambient relative humidity.

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