An ice layer pore distribution detector and a detection method

Abstract

The application discloses an ice layer pore distribution detector and a detection method, and relates to the technical field of aviation detection.The detector comprises an ultrasonic pulse generation circuit, a multi-frequency ultrasonic transducer probe, an ultrasonic pulse receiving circuit, a high-frequency voltage signal acquisition and amplification circuit, a high-precision resistance temperature measurement module and a multi-source digital signal processing module.The ultrasonic pulse generation circuit is used to generate and emit starting pulse signals with different frequencies.The multi-frequency ultrasonic transducer probe is used to receive the starting pulse signals and emit them into an ice layer to be detected, and receive and emit echo signals and temperature signals from the ice layer to be detected.The ultrasonic pulse receiving circuit is used to receive the echo signals.The high-frequency voltage signal acquisition and amplification circuit is used to acquire, amplify and transmit the echo signals.The high-precision resistance temperature measurement module is used to acquire and transmit the temperature signals.The multi-source digital signal processing module is electrically connected with the high-frequency voltage signal acquisition and amplification circuit and the high-precision resistance temperature measurement module, and is used to receive and process the echo signals and the temperature signals.The application effectively solves the problem that a traditional icing sensor cannot measure the pore distribution of an ice layer, and is conducive to evaluating icing hazards in application scenarios sensitive to the properties of the ice layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aviation detection technology, in particular to an ice layer pore distribution detector and a detection method. BACKGROUND

[0002] When an aircraft encounters supercooled water droplets in the cloud, ice accumulation may occur at the windward surface of the aircraft, the engine inlet and other positions, thereby affecting the lift-drag ratio of the aircraft and causing the aerodynamic performance of the aircraft to decline, which may lead to air crash accidents. Such incidents are common, and therefore icing environment is considered as one of the meteorological conditions that seriously threaten the safety of aircraft operation. Traditional icing sensors focus on detecting single ice layer thickness, morphology and other information, and the observation dimension is limited. However, obtaining pore state information is crucial for determining ice type and researching precise deicing technology, especially in application scenarios sensitive to ice layer properties, which is of great significance for evaluating icing disaster hazards.

[0003] Patent application CN202110599411.7 discloses an ice detection device and method based on a complex impedance sensor, which calculates the impedance modulus in the low frequency band and the relative dispersion index of the equivalent capacitance of the measured region to determine the state of the surface of the target structure, effectively avoiding the influence of external airflow velocity on measurement accuracy and accuracy. The principle of this patent application is clear and the effect is obvious, but the dielectric constant of ice is affected by humidity, temperature, salinity and other factors, and the measurement accuracy and system stability need to be improved.

[0004] Patent application CN202011578970.1 discloses an ultrasonic guided wave detection system based on a piezoelectric film, which transmits and receives different waveform excitation signals to detect the thickness of the icing on the outer surface of the wing and the icing area. This patent application is simple to operate and easy to maintain, but the ultrasonic detection based on guided waves has poor detection capability in the longitudinal direction of the ice layer, and can only provide ice layer characteristics based on attenuation rate through time domain analysis, making it difficult to obtain key information such as ice layer pore and ice type. SUMMARY

[0005] The present application provides an ice layer pore distribution detector and a detection method, which can solve the problems in the prior art.

[0006] The present application provides an ice layer pore distribution detector, comprising:

[0007] An ultrasonic pulse generation circuit for generating and transmitting a starting pulse signal of different frequencies;

[0008] A multi-frequency ultrasonic transducer probe installed on the wing surface of the aircraft and electrically connected to the ultrasonic pulse generation circuit, for receiving the starting pulse signal and transmitting it to the ice layer to be measured, and simultaneously receiving and transmitting echo signals and temperature signals from the ice layer to be measured;

[0009] An ultrasonic pulse receiving circuit is electrically connected with the multi-frequency ultrasonic transducer probe, and used for receiving the echo signal;

[0010] A high-frequency voltage signal acquisition and amplification circuit is electrically connected with the ultrasonic pulse receiving circuit, and used for acquiring, amplifying and transmitting the echo signal;

[0011] A high-precision resistance temperature measurement module is electrically connected with the multi-frequency ultrasonic transducer probe, and used for acquiring and transmitting the temperature signal;

[0012] A multi-source digital signal processing module is electrically connected with the high-frequency voltage signal acquisition and amplification circuit and the high-precision resistance temperature measurement module, and used for receiving and processing the echo signal and the temperature signal.

[0013] Preferably, the multi-frequency ultrasonic transducer probe is connected with the high-precision resistance temperature measurement module through a temperature signal transmission cable, and connected with the ultrasonic pulse generating circuit and the ultrasonic pulse receiving circuit through an ultrasonic pulse signal transmission cable, and the multi-frequency ultrasonic transducer probe comprises:

[0014] The ultrasonic wedge is provided with a protective film on the upper end surface;

[0015] A temperature sensing element is connected with the temperature signal transmission cable, and used for acquiring the temperature signal of the ice layer to be measured;

[0016] A piezoelectric wafer set is connected with the ultrasonic pulse signal transmission cable, and the piezoelectric wafer set comprises a high-frequency wafer, a medium-frequency wafer and a low-frequency wafer, and is used for receiving the starting pulse signal and emitting it into the ice layer to be measured, receiving and emitting the echo signal from the ice layer to be measured, and converting the echo signal of the ice layer to be measured into an electric signal;

[0017] The piezoelectric wafer set and the temperature sensing element are installed on the lower end surface of the ultrasonic wedge in a rectangular array manner.

[0018] Preferably, the excitation function of the starting pulse signal is:

[0019]

[0020] wherein,

[0021]

[0022] In the formula, f0 is the center frequency of the excitation pulse, t is the time of excitation, t1 is the time of medium-frequency excitation pulse generation, t2 is the time of high-frequency excitation pulse generation, and n is the number of Hanning windows added.

[0023] Preferably, the piezoelectric wafer group adopts time division multiplexing, when the center frequency of the initial pulse is high frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the high frequency wafer; when the center frequency of the initial pulse is medium frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the medium frequency wafer; when the center frequency of the initial pulse is low frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the low frequency wafer.

[0024] A detection method of an ice layer pore distribution detector, characterized by comprising the following steps:

[0025] The ultrasonic pulse generation circuit generates and emits initial pulse signals of different frequencies;

[0026] The multi-frequency ultrasonic transducer probe receives the initial pulse signals and emits them into the ice layer to be measured, and receives and emits echo signals and temperature signals from the ice layer to be measured;

[0027] The high-frequency voltage signal acquisition and amplification circuit acquires and transmits the echo signals, and the high-precision resistance temperature measurement module acquires and transmits the temperature signals;

[0028] The multi-source digital signal processing module receives and processes the echo signals and the temperature signals, specifically comprising the following steps:

[0029] The time domain signal analysis method is used to extract the peak time t0 and the relative peak amplitude P of the first echo of the echo signal under the medium frequency pulse signal dk ;

[0030] According to the temperature signal and the peak time t0 of the first echo, the thickness d of the ice layer to be measured is calculated;

[0031] According to the thickness d and the relative peak amplitude P of the first echo dk , the state of the ice layer to be measured is identified;

[0032] When the ice layer to be measured is determined to be in an ice state, the high-order harmonic ratio η of the echo signal is calculated, and the ice type of the ice layer to be measured is identified according to the high-order harmonic ratio η;

[0033] According to the identified ice type, the echo signals corresponding to different frequency pulses are obtained, and the scale lateral compression characteristic A p and the scale longitudinal compression characteristic N s of the ice layer pore are calculated by the time-frequency dynamic compression method.

[0034] The scale longitudinal compression characteristic N s is used to identify the range of pore diameters, and the relative peak amplitude P of the first echo dk and the scale lateral compression characteristic A p are used to identify the pore quantity and size information of the ice layer to be measured.

[0035] Preferably, the thickness d of the ice layer to be measured is calculated using the following formula:

[0036]

[0037] In the formula, v(T) is the propagation speed of the ultrasonic signal, and d0 is the thickness of the acoustic wedge;

[0038] The higher harmonic ratio η of the echo signal is calculated using the following formula:

[0039]

[0040] In the formula, The fundamental amplitude, This represents the amplitude of the second harmonic.

[0041] The porosity distribution characteristics of the ice layer are calculated using the following formula: A. p and depth compression feature N s :

[0042]

[0043]

[0044] In the formula, To extract the wavelet scale s i Number of intervals; A s The total area of ​​the time-frequency region of a single echo. The wavelet image is compressed to a scale of s i The sum of pixels in the interval, where i is the index of the scale interval, with values ​​of 1, 3, 5, 7, ...

[0045] Preferably, based on the thickness d and the relative peak amplitude P of the first echo... dk The state of the ice layer to be tested is identified, specifically including the following situations:

[0046] When the relative peak amplitude P of a single echo dk When the value is 0, the state of the ice layer to be measured is unloaded;

[0047] When the relative peak amplitude P of a single echo dk Not less than the relative peak threshold of the current ice thickness At that time, the state of the ice layer to be tested was frozen;

[0048] When the relative peak amplitude P of a single echo dk The relative peak threshold of ice layers smaller than the current thickness When the value is greater than 0, the state of the ice layer to be tested is a water film;

[0049] in,

[0050]

[0051] In the formula, V0 is the excitation voltage. This represents the peak amplitude of a single echo under the current thickness conditions in the water film state.

[0052] Preferably, the method further includes establishing an ice layer information database through experimental methods, which includes the open ice harmonic ratio threshold η. G And frost harmonic ratio threshold η R The proportional relationship between pore diameter and scale depth compression characteristics under different thickness conditions, and the relationship curves between pore distribution and relative peak amplitude and scale lateral compression characteristics.

[0053] Preferably, the ice type of the ice layer under test is identified based on the higher harmonic ratio η, specifically including the following situations:

[0054] When the higher harmonic ratio η is less than the Mingbing harmonic ratio threshold η G At that time, the ice layer to be tested was open ice;

[0055] When the higher harmonic ratio η is greater than the luminous ice harmonic ratio threshold η G And less than the frost harmonic ratio threshold η R At that time, the ice layer being tested was of mixed ice type;

[0056] When the higher harmonic ratio η is greater than the frost harmonic ratio threshold η R At that time, the ice layer to be tested was classified as frost ice.

[0057] Preferably, the scale-depth compression characteristics N of ice layer porosity will be calculated using the time-frequency dynamic compression method. s Substituting into the proportional relationship, the range of pore diameter is identified; the relative peak amplitude P of the first echo is... dk Scale-based lateral compression feature A p Substitute the data into the relationship curve to identify the number and size of pores in the ice layer under test.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] (1) This invention acquires multi-frequency echo signals and uses time-frequency analysis to identify ice thickness and ice type, thereby obtaining accurate ice layer thickness, ice layer state and icing type, and effectively extracts key features characterizing pore distribution, providing a reliable basis for precise anti-icing and de-icing systems.

[0060] (2) Since the present invention uses multi-frequency ultrasonic longitudinal wave detection, it is not affected by external environmental factors, has stable performance, and is suitable for various extreme weather conditions and complex environments. Moreover, the method of the present application is simple and easy to implement and can be used in engineering applications. Attached Figure Description

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these accompanying drawings without any creative effort.

[0062] Figure 1 A structural schematic diagram of an ice layer pore distribution detector according to the present application;

[0063] Figure 2 A structural schematic diagram of a multi-frequency ultrasonic transducer probe according to the present application;

[0064] Figure 3 A flowchart of a detection method of an ice layer pore distribution detector according to the present application. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0066] With reference to Figure 1 The present application provides an ice layer pore distribution detector, which adopts the principle of ultrasonic longitudinal wave detection, acquires ice layer echo signals obtained by excitation at different frequencies, fuses ice layer features identified at multiple frequencies, acquires ice layer pore distribution information, and realizes multi-dimensional and high-precision icing detection. The detector comprises an ultrasonic pulse generation circuit, a multi-frequency ultrasonic transducer probe, an ultrasonic pulse receiving circuit, a high-frequency voltage signal acquisition and amplification circuit, a high-precision resistance temperature measurement module, and a multi-source digital signal processing module.

[0067] The ultrasonic pulse generating circuit is used for generating and emitting a starting pulse signal of different frequencies; the multi-frequency ultrasonic transducer probe is installed on the aircraft wing surface, and is electrically connected with the ultrasonic pulse generating circuit, used for receiving the starting pulse signal and emitting it to the ice layer to be measured, and receiving and emitting the echo signal and the temperature signal from the ice layer to be measured; the ultrasonic pulse receiving circuit is electrically connected with the multi-frequency ultrasonic transducer probe, used for receiving the echo signal; the high-frequency voltage signal acquisition and amplification circuit is electrically connected with the ultrasonic pulse receiving circuit, used for acquiring and amplifying the echo signal, and transmitting the amplified echo signal; the high-precision resistance temperature measurement module is electrically connected with the multi-frequency ultrasonic transducer probe, used for acquiring and transmitting the temperature signal; the multi-source digital signal processing module is electrically connected with the high-frequency voltage signal acquisition and amplification circuit and the high-precision resistance temperature measurement module, used for receiving and processing the echo signal and the temperature signal, so as to obtain the characteristics of the ice layer to be measured.

[0068] In the embodiment, the sampling rate of the original data requires to reach 200 times of the center frequency of the excitation function, and the echo signal is intercepted from the beginning of the excitation signal to the end of the second echo as a signal acquisition band.

[0069] With reference to Figure 2 , the multi-frequency ultrasonic transducer probe is connected with the high-precision resistance temperature measurement module through a temperature signal transmission cable, and is connected with the ultrasonic pulse generating circuit and the ultrasonic pulse receiving circuit through an ultrasonic pulse signal transmission cable. The multi-frequency ultrasonic transducer probe is composed of a sound transmission wedge, a piezoelectric wafer group and a temperature sensing element. A protective film is installed on the upper end surface (A surface in Figure 2 ) of the sound transmission wedge, and the piezoelectric wafer group and the temperature sensing element are adhered with damping blocks and are installed on the lower end surface of the sound transmission wedge in a rectangular array. The temperature sensing element is connected with the temperature signal transmission cable. The piezoelectric wafer group is connected with the ultrasonic pulse signal transmission cable. The piezoelectric wafer group includes a high-frequency wafer 101, a medium-frequency wafer 102 and a low-frequency wafer 103, and is used for converting the echo signal of the ice layer to be measured into an electric signal. The high-frequency wafer 101 of the piezoelectric wafer group is selected from wafers with a resonance frequency of 5-50 MHz, the medium-frequency wafer 102 is selected from wafers with a resonance frequency of 1-5 MHz, and the low-frequency wafer 103 is selected from wafers with a resonance frequency of 10-1000 KHz. In the present application, the high-frequency wafer with a resonance frequency of 20 MHz, the medium-frequency wafer with a resonance frequency of 1 MHz and the low-frequency wafer with a resonance frequency of 100 KHz are selected. In order to meet the emission and reception requirements of different frequency excitations, the wafer material can be selected from silicon dioxide, lithium sulfate, lithium iodate and lithium niobate, and preferably, the wafer material is selected from lithium sulfate with good receiving performance, the sound transmission wedge is selected from organic glass, and the damping block is selected from epoxy resin.

[0070] The piezoelectric wafer group and the temperature sensing element are installed on the upper end inclined surface of the sound transmission wedge in a rectangular array mode, and are connected to the ultrasonic pulse signal transmission cable and the temperature signal transmission cable, and the protective film is installed on the lower end surface of the sound transmission wedge to form the detection end surface which contacts the ice layer to be detected.

[0071] The array structure of the piezoelectric wafer and the temperature sensing element is designed in the multi-frequency ultrasonic transducer probe structure, so that the multi-frequency ultrasonic transducer probe structure is exquisite, the installation position is flexible, and the multi-frequency ultrasonic transducer probe structure can be installed on the structure surface such as a wing which has a flush requirement.

[0072] The excitation function of the start pulse signal is:

[0073]

[0074] wherein,

[0075]

[0076] In the formula, f0 is the center frequency of the excitation pulse, t is the time of excitation, t1 is the time of the medium frequency excitation pulse, t2 is the time of the high frequency excitation pulse, and n is the number of added Hanning windows.

[0077] The piezoelectric wafer group of the present application adopts the time division multiplexing mode, when the center frequency of the start pulse is high frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the high frequency wafer; when the center frequency of the start pulse is medium frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the medium frequency wafer; and when the center frequency of the start pulse is low frequency, the ultrasonic pulse signal transmission cable transmits the echo signal from the low frequency wafer.

[0078] In the present embodiment, when the center frequency f0 of the start pulse is 20MHz, the transmission and reception cable transmits the echo signal from the high frequency wafer pair; when f0 is 1MHz, the transmission and reception cable transmits the echo signal from the medium frequency wafer pair; and when f0 is 100KHz, the transmission and reception cable transmits the echo signal from the low frequency wafer pair.

[0079] Reference Figure 3The application further provides a detection method based on the ice layer pore distribution detector, wherein the embedded data processing device receives the echo signal from the high-frequency voltage signal collection and amplification circuit and the ice layer temperature signal from the high-precision resistance temperature measurement module, and calculates the peak time t0 of the first echo of the ice layer to be detected according to the echo signal, the relative peak amplitude P dk of the first echo, and the size relationship between the relative peak amplitude P dk of the first echo and the corresponding threshold value to determine the state of the ice layer to be detected. Furthermore, the ratio of the high-order harmonic wave η and the scale lateral compression characteristic A p and the depth compression characteristic N s are calculated to identify the icing type of the ice layer to be detected. Specifically, the method comprises the following steps:

[0080] Step 1: Establishing an ice layer information database. The ice layer detection system collects the echo signals under high-frequency, medium-frequency and low-frequency excitation when the ice layer thickness is 1-5 mm and the ice layer state is water film, clear ice, mixed ice and frost ice, wherein the ice layer state covers different pore distribution ice layers formed under various weather conditions.

[0081] The relative peak amplitude P dk , the ratio of the high-order harmonic wave η, the scale lateral compression characteristic A p and the depth compression characteristic N s of the ice layer with different pore distributions under different thickness conditions are calculated. The range of the ratio of the high-order harmonic wave η of the ice layer with different thicknesses corresponding to the three icing types of clear ice, mixed ice and frost ice is obtained to obtain the harmonic ratio threshold η G of clear ice and the harmonic ratio threshold η R of frost ice, and the proportional relationship between the pore diameter and the depth compression characteristic N s under different thickness conditions and the relationship curve between the pore distribution and the relative peak amplitude P dk and the scale lateral compression characteristic A p are fitted respectively.

[0082] Step 2: The peak time t0 and the relative peak amplitude P dk of the first echo of the echo signal under the medium-frequency pulse signal are extracted by using the time domain signal analysis method.

[0083] Step 3: The thickness d of the ice layer to be detected is calculated according to the temperature and the peak time t0 of the first echo. The thickness d of the ice layer to be detected is calculated by the following formula:

[0084]

[0085] In the formula, v(T) is the ultrasonic signal propagation speed, and d0 is the thickness of the sound-transparent wedge.

[0086] Step 4: Based on the thickness d and the relative peak amplitude P of the first echo. dk The state of the ice layer to be measured is identified. Combined with the calculated ice thickness d, when the relative peak amplitude P of a single echo... dk When the value is 0, the state of the ice layer to be measured is unloaded. When the relative peak amplitude P of a single echo is 0, the state of the ice layer to be measured is unloaded. dk Not less than the relative peak threshold of the current ice thickness At that time, the state of the ice layer to be measured is icy, and when the relative peak amplitude P of a single echo is... dk The relative peak threshold of ice layers smaller than the current thickness When the value is greater than 0, the state of the ice layer to be tested is a water film.

[0087]

[0088] in,

[0089]

[0090] In the formula, V0 is the excitation voltage. This represents the peak amplitude of a single echo under the current thickness conditions in the water film state.

[0091] Step 5: When the ice layer to be tested is determined to be in an icy state, calculate the higher harmonic ratio η of the echo signal and compare it with the range measured in the ice layer information database. Based on the higher harmonic ratio η, identify the icing type of the ice layer to be tested.

[0092] The higher harmonic ratio η of the echo signal is calculated using the following formula:

[0093]

[0094] In the formula, The fundamental amplitude, This represents the amplitude of the second harmonic.

[0095] When the higher harmonic ratio η is less than the Mingbing harmonic ratio threshold η G At that time, the ice layer to be tested was open ice;

[0096] When the higher harmonic ratio η is greater than the luminous ice harmonic ratio threshold η G And less than the frost harmonic ratio threshold η R At that time, the ice layer being tested was of mixed ice type;

[0097] When the higher harmonic ratio η is greater than the frost harmonic ratio threshold η R At that time, the ice layer to be tested was classified as frost ice.

[0098]

[0099] The sixth step is to obtain the echo signals corresponding to different frequency pulses according to the identified icing type, and calculate the scale lateral compression characteristic A of the ice layer pore through the time-frequency dynamic compression method p And the scale longitudinal compression characteristic N s .

[0100] When the icing type of the ice layer to be measured is clear ice, a high-frequency echo signal of 20MHz is selected for pore characteristic extraction; when the icing type of the ice layer to be measured is mixed ice, a medium-frequency echo signal of 1MHz is selected; and when the icing type of the ice layer to be measured is frost ice, a low-frequency echo signal of 100KHz is selected. According to the selected echo signal, the time-frequency dynamic compression analysis method is used to calculate the ice layer pore distribution characteristics: the first echo signal is intercepted for wavelet transform, the obtained wavelet coefficients are normalized to obtain wavelet scales and are mapped to a three-dimensional coordinate space, the wavelet three-dimensional image is cut into several interval segments from top to bottom using an increasing scale interval, and the interval segments are compressed to a two-dimensional plane, and the scale lateral compression characteristic A p And the longitudinal compression characteristic N s ,

[0101] The scale lateral compression characteristic A p And the longitudinal compression characteristic N s of the ice layer pore are calculated by the following formula:

[0102]

[0103]

[0104] In the formula, is the number of interval segments with a wavelet scale of s i , A s is the total area of the first echo time-frequency region, is the sum of pixels of the interval segment with a wavelet scale of s i after compression, and i is the serial number of the scale interval, which is 1, 3, 5, 7, ….

[0105] The seventh step is to substitute the scale longitudinal compression characteristic N s of the ice layer pore calculated through the time-frequency dynamic compression method into the proportional relationship to identify the range of pore diameter; and substitute the relative peak amplitude P dk of the first echo and the scale lateral compression characteristic A p into the relationship curve to identify the pore quantity and size information of the ice layer to be measured.

[0106] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims include all such modifications and variations as fall within the scope of the present application.

[0107] It is apparent that those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. It is therefore intended that the present application cover all such changes and modifications that are within its scope.

Claims

1. A method of detecting a pore distribution of an ice layer, characterized by, The ice layer pore distribution detector comprises: An ultrasonic pulse generating circuit for generating and emitting a starting pulse signal of different frequencies; A multi-frequency ultrasonic transducer probe installed on the aircraft wing surface and electrically connected to the ultrasonic pulse generating circuit, for receiving and emitting the starting pulse signal into the ice layer to be measured, and receiving and emitting echo signals and temperature signals from the ice layer to be measured; An ultrasonic pulse receiving circuit electrically connected to the multi-frequency ultrasonic transducer probe, for receiving the echo signals; A high-frequency voltage signal acquisition and amplification circuit electrically connected to the ultrasonic pulse receiving circuit, for acquiring, amplifying and transmitting the echo signals; A high-precision resistance temperature measurement module electrically connected to the multi-frequency ultrasonic transducer probe, for acquiring and transmitting the temperature signals; A multi-source digital signal processing module electrically connected to the high-frequency voltage signal acquisition and amplification circuit and the high-precision resistance temperature measurement module, for receiving and processing the echo signals and the temperature signals; The detection method comprises the following steps: Adopt time domain signal analysis method to extract the peak time of the first echo of the echo signal under the medium frequency pulse signal and relative peak amplitude ; According to the temperature signal and the peak time of the first echo , the thickness of the ice layer to be measured is calculated ; According to the thickness Relative peak amplitude of the first echo identifying the state of the ice layer When the ice layer to be measured is determined to be in the icing state, a high harmonic ratio of the echo signal is calculated , and the icing type of the ice layer to be measured is identified according to the high harmonic ratio . According to the identified icing type, the echo signals corresponding to different frequency pulses are obtained, and the scale lateral compression characteristics and scale longitudinal compression characteristics of the ice layer pores are calculated by a time-frequency dynamic compression method and scale longitudinal compression characteristics ​ By scale depth compression features Identifying a range of pore diameters from the relative peak amplitude of the first echo With scale lateral compression features Identifying the number and size information of the pores of the ice layer to be measured The scale lateral compression characteristic of the ice layer pore is calculated by the following formula and the scale longitudinal compression characteristic : In the formula, is the wavelet scale intercepted the number of interval segments; is the total area of the first echo time-frequency region, is the wavelet scale after wavelet image compression the sum of the pixels of the interval segment, is the serial number of the scale interval, taking values of 1, 3, 5, 7, … 2. A method of detecting an ice layer porosity probe according to claim 1, wherein, The multi-frequency ultrasonic transducer probe is connected to the high-precision resistance temperature measurement module through a temperature signal transmission cable, and is connected to the ultrasonic pulse generating circuit and the ultrasonic pulse receiving circuit through an ultrasonic pulse signal transmission cable, and the multi-frequency ultrasonic transducer probe comprises: An acoustic wedge with a protective film installed on the upper end surface; A temperature sensing element (104) connected to the temperature signal transmission cable, for acquiring the temperature signals of the ice layer to be measured; A piezoelectric wafer set connected to the ultrasonic pulse signal transmission cable, the piezoelectric wafer set comprising a high-frequency wafer (101), a medium-frequency wafer (102) and a low-frequency wafer (103), for receiving and emitting the starting pulse signal into the ice layer to be measured, and receiving and emitting the echo signals from the ice layer to be measured, and converting the echo signals of the ice layer to be measured into electrical signals; The piezoelectric wafer set and the temperature sensing element are installed on the lower end surface of the acoustic wedge in a rectangular array.

3. A method of detecting a distribution of ice layer porosity as claimed in claim 2, wherein, The excitation function of the starting pulse signal is: Wherein, wherein is the center frequency of the excitation pulse, is the time of excitation onset, is the time of mid-frequency excitation pulse onset, is the time of high-frequency excitation pulse onset, is the number of Hanning windows applied.

4. A method of detecting a distribution of ice layer porosity as claimed in claim 2, wherein, The piezoelectric wafer set adopts time division multiplexing, when the center frequency of the starting pulse is high frequency, the ultrasonic pulse signal transmission cable transmits the echo signals from the high-frequency wafer (101); when the center frequency of the starting pulse is medium frequency, the ultrasonic pulse signal transmission cable transmits the echo signals from the medium-frequency wafer (102); when the center frequency of the starting pulse is low frequency, the ultrasonic pulse signal transmission cable transmits the echo signals from the low-frequency wafer (103).

5. A method of detecting a distribution of ice layer porosity as claimed in claim 2, wherein, The thickness of the ice layer to be measured is calculated by the following formula : wherein is the speed of ultrasound signal propagation, is the thickness of the acoustic wedge; The ratio of the higher harmonics of the echo signal is calculated by the formula : wherein is the fundamental amplitude, is the second harmonic amplitude.

6. A method of detecting a distribution of ice layer porosity as claimed in claim 1, wherein, According to the thickness Relative peak amplitude of the first echo Identify the state of the ice layer to be measured, including the following cases: When the relative peak amplitude of the once-echo is 0, the state of the ice layer to be measured is empty load; when the relative peak amplitude of the once-reflected echo is not less than the relative peak threshold value of the current thickness ice layer the state of the ice layer to be measured is frozen; When the relative peak amplitude of the once-echo is less than the relative peak threshold of the current thickness ice layer and greater than 0, the state of the ice layer under test is a water film; Wherein, wherein is the excitation voltage, is the peak amplitude of the first echo at the current thickness condition for the water film state.

7. A method of detecting a distribution of ice layer porosity as claimed in claim 1, wherein, Also included is the establishment of an ice layer information database by experimental methods, the database including clear ice harmonic ratio threshold values and hoar frost harmonic ratio threshold values , the proportional relationship between pore diameter and scale depth compression characteristics under different thickness conditions, and the relationship curve between pore distribution and relative peak amplitude and scale transverse compression characteristics.

8. A method of detecting a distribution of ice layer porosity as claimed in claim 7, wherein, According to the ratio of the higher harmonic The ice layer to be measured is identified, and the ice formation type is identified The following cases are included: When the high harmonic ratio is less than the clear ice harmonic ratio threshold , the ice layer icing type to be measured is clear ice; When the high harmonic ratio is greater than the clear ice harmonic ratio threshold and less than the hoar ice harmonic ratio threshold , the ice layer icing type to be measured is mixed ice; When the high harmonic ratio is greater than the frost ice harmonic ratio threshold , the ice layer icing type to be measured is frost ice.

9. A method of detecting a distribution of ice layer porosity as claimed in claim 7, wherein, The scale longitudinal compression characteristics of the ice layer pore are calculated by the time-frequency dynamic compression method The range of the pore diameter is identified in the proportional relationship; the relative peak amplitude of the first echo and the scale lateral compression characteristics The ice layer pore quantity and size information to be measured are identified in the relationship curve.

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