A four-hole supersonic probe without experimental calibration

Abstract

A four-hole supersonic probe that does not require test calibration relates to a supersonic probe. The probe body adopts a seamless steel pipe with a bend near the bottom end, and four channel tubes extending with the probe body are arranged in the middle position inside. The four channel tubes are arranged at equal angles along the axis of the probe body and are solidly welded to the probe body. The front edge of the probe body is polished to form a conical probe for the measuring end. The four channel tubes are vertically connected with the conical probe busbar to form 4 holes. The 4 holes are all located at 50% of the busbar of the conical probe. The probe uses the slender cone theory under supersonic conditions to derive various aerodynamic parameters. The shock wave loss is small, and it helps to ensure the static pressure of the leading edge of the measured cone. The calibration coefficients are obtained through the slender cone theory, which greatly shortens the experimental time.

Description

Technical Field

[0001] The invention relates to a super transonic probe, in particular to a four-hole super transonic probe which does not require test calibration, and belongs to the technical field of contact flow field measurement. Background Art

[0002] With the advancement of science and technology and the cross-application of disciplines, optical measurement is often used in flow field measurement due to its non-contact and high-precision measurement. However, optical measurement is based on the principle of optical contrast, so it has high requirements for measurement viewing angle, temperature, lighting, and surface reflection. In addition, it is often impossible to install optical windows in flow fields with complex internal structures such as the engine, resulting in non-contact measurement of internal flow field parameters. The pneumatic pressure probe based on differential pressure measurement can be used inside high-temperature and high-pressure engines, and the use of a tiny-sized probe has less obstruction and influence on the flow field. Therefore, it is often used in various flow field experiments such as compressor flow field, turbine rotor outlet flow field, guide vane outlet flow field, and supersonic flow.

[0003] Since the probe itself has a certain interference on the measured flow field, especially in the supersonic flow field, a detached shock wave often appears at the leading edge of the probe, increasing the flow field exit loss. In order to minimize the shock wave loss of the probe itself, a smaller semi-cone angle is often used, generally 5-10°. This also causes the incoming flow to easily separate at the probe measuring hole when the angle of attack is above 15°, resulting in a decrease in measurement accuracy and even unacceptable errors in engineering. In addition, the probe needs to be calibrated for measurement data before use, and the measurement of calibration parameters often takes up more experimental resources and time, resulting in inconvenience in the actual use of the probe.

[0004] Therefore, designing a four-hole supersonic probe that does not require calibration is of great significance in engineering applications. Summary of the invention

[0005] In order to solve the shortcomings of the background technology, the present invention provides a four-hole supersonic probe that does not require experimental calibration. It has a small shock wave loss and helps to ensure the static pressure at the leading edge of the measured cone. The calibration coefficients are obtained through theoretical calculation of a slender cone, which greatly shortens the experimental time.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A four-hole supersonic probe that does not require test calibration, including a probe body and a conical probe. The probe body adopts a seamless steel pipe with a bend near the bottom, and four channel tubes extending with the probe body are arranged in the middle of the probe body. The four channel tubes are arranged at equal angles along the axis of the probe body and are solidly welded to the probe body. The front edge of the probe body is polished to form a conical probe for the measuring end. The four channel tubes are vertically connected with the generatrix of the conical probe to form 4 hole positions including No. 1 hole position, No. 2 hole position, No. 3 hole position and No. 4 hole position. The 4 hole positions are all located at 50% generatrix of the conical probe. The aerodynamic parameters of the probe derived by the slender cone theory under supersonic conditions are as follows:

[0008] Cone probe zero angle of attack surface pressure coefficient distribution:

[0009]

[0010] Distribution of additional pressure coefficient of cone probe at non-zero attack angle:

[0011]

[0012] The conversion relationship between pitch angle and yaw angle and circular angle and cone angle is:

[0013]

[0014]

[0015]

[0016]

[0017] Pressure coefficient distribution of cone probe at non-zero attack angle:

[0018] C p =C p0 +ΔC p

[0019] Substitute the pressure coefficient definition formula into The pressure distribution of the four holes is obtained:

[0020]

[0021]

[0022]

[0023]

[0024] In the formula, δ represents the cutting angle at the location, γ represents the specific heat ratio of 1.4, α represents the yaw angle, β represents the pitch angle, and θ represents the cone angle. represents the circumference angle, represents the unified similarity parameter, represents the incoming flow density, R represents the thermodynamic constant, which is 8.314 J·mol -1 ·K -1 , T represents the static temperature of the incoming flow, V ∞ Indicates the incoming flow velocity, P ∞ Indicates the static pressure of the incoming flow;

[0025] The idea of ​​partition calibration is to divide the probe into four areas according to the circular angle. The calibration formula is as follows:

[0026] Calibration coefficient of airflow yaw angle α for each partition:

[0027]

[0028] Calibration coefficient of airflow pitch angle β for each partition:

[0029]

[0030] Total pressure calibration coefficient for each partition:

[0031]

[0032] Static pressure calibration coefficient for each zone:

[0033]

[0034] Where P n Indicates the hole with the highest pressure, K αn Indicates the n-zone yaw angle calibration coefficient, K βn represents the pitch angle calibration coefficient of zone n, C ptn Indicates the total pressure calibration coefficient of zone n, C psn Indicates the static pressure calibration coefficient of zone n, n = 1 to 4, corresponding to the circumferential angle interval Where: when n = 1, n-1 = 4, when n = 4, n+1 = 1, P t and P s Indicates the total pressure and static pressure of the incoming flow.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The probe of the present invention has a smaller shock wave angle. In particular, when the semi-cone angle of the conical probe is set to 15°, studies have shown that the cone can still maintain a conical shock wave within a larger attack angle range. Therefore, compared with the blunt body shock wave generated by a probe with a total pressure hole at the leading edge of a conventional five-hole or three-hole probe, the probe of the present invention has a smaller shock wave loss;

[0037] 2. The four holes are arranged at equal angles along the axis of the probe body and are vertically connected to the generatrix of the cone probe. This design can reduce the deviation caused by the different direction components of the measured pressure due to the large pressure measuring area, and ensure the static pressure of the front edge of the measured cone as much as possible;

[0038] 3. The direction of the probe is obtained by calculation, which avoids the calibration process required before the probe is used, greatly shortening the experimental time;

[0039] 4. The idea of ​​partition calibration is adopted to ensure the capture of total pressure when the probe is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the overall structure of the probe of the present invention;

[0041] Figure 2 It is a schematic structural diagram of a conical probe of the probe of the present invention;

[0042] Figure 3 is a schematic diagram of the pitch angle and yaw angle of the probe of the present invention;

[0043] Figure 4 is a schematic diagram of the circumference angle and cone angle of the probe of the present invention;

[0044] Figure 5 It is a schematic diagram of the area division of the conical probe of the probe of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0046] like Figure 1 to Figure 5As shown, a four-hole supersonic probe that does not require test calibration includes a probe body 5 and a conical probe 6. The probe body 5 is a seamless steel pipe with a bend near the bottom end, and four channel tubes extending with the probe body 5 are arranged at equal angles along the axis of the probe body 5 and are solidly welded to the probe body 5. The front edge of the probe body 5 is polished to form a conical probe 6 as a measuring end. The four channel tubes are vertically connected with the generatrix of the conical probe 6 to form 4 hole positions including No. 1 hole position 1, No. 2 hole position 2, No. 3 hole position 3 and No. 4 hole position 4. The 4 hole positions are all located at 50% of the generatrix of the conical probe 6. The 4 hole positions are used as measuring holes. The channel tube is at the bend of the conical probe 6 to the probe body 5 as the inlet section, and the channel tube is at the bend of the probe body 5 to the top of the probe body 5 as the collection section. The aerodynamic parameters of the probe derived by the slender cone theory under supersonic conditions are as follows:

[0047] Cone probe 6 zero attack angle surface pressure coefficient distribution:

[0048]

[0049] Distribution of additional pressure coefficient of cone probe 6 at non-zero attack angle:

[0050]

[0051] The conversion relationship between pitch angle and yaw angle and circular angle and cone angle is:

[0052]

[0053]

[0054]

[0055]

[0056] Pressure coefficient distribution of cone probe 6 at non-zero attack angle:

[0057] C p =C p0 +ΔC p

[0058] Substitute the pressure coefficient definition formula into The pressure distribution of the four holes is obtained:

[0059]

[0060]

[0061]

[0062]

[0063] In the formula, δ represents the cutting angle at the location, γ represents the specific heat ratio of 1.4, α represents the yaw angle, β represents the pitch angle, and θ represents the cone angle. represents the circumference angle, represents the unified similarity parameter, represents the incoming flow density, R represents the thermodynamic constant, which is 8.314 J·mol -1 ·K -1 , T represents the static temperature of the incoming flow (measured by a temperature probe in a wind tunnel), V ∞ represents the incoming flow velocity (calculated from the data measured by the Pitot tube in front of the wind tunnel), P ∞ Indicates the static pressure of the incoming flow (measured by the pitot tube in front of the wind tunnel);

[0064] The idea of ​​partition calibration is to divide the probe into four areas according to the circular angle. The calibration formula is as follows:

[0065] Calibration coefficient of airflow yaw angle α for each partition:

[0066]

[0067] Calibration coefficient of airflow pitch angle β for each partition:

[0068]

[0069] Total pressure calibration coefficient for each partition:

[0070]

[0071] Static pressure calibration coefficient for each zone:

[0072]

[0073] Where P n Indicates the hole with the highest pressure, K αn Indicates the n-zone yaw angle calibration coefficient, K βn represents the pitch angle calibration coefficient of zone n, C ptn Indicates the total pressure calibration coefficient of zone n, C psn Indicates the static pressure calibration coefficient of zone n, n = 1 to 4, corresponding to the circumferential angle interval Where: when n = 1, n-1 = 4, when n = 4, n+1 = 1, P t and P s Indicates the total pressure and static pressure of the incoming flow (measured by the Pitot tube at the inlet section of the wind tunnel).

[0074] The semi-cone angle of the conical probe 6 of the present invention is preferably set to 15°, which reduces the volume of the conical probe 6 as much as possible while ensuring the installation volume required for each measuring hole. Compared with the blunt body shock wave generated by a probe with a total pressure hole at the leading edge of a conventional five-hole or three-hole probe, it has smaller shock wave losses. The probe has only four measuring holes, and the total pressure probe at the leading edge of the cone head of the conventional probe is eliminated, reducing the influence of the detached shock wave at the leading edge of the probe on the measurement result in the supersonic flow field. In addition, various calibration coefficients are obtained through theoretical calculation of a slender cone, which saves a lot of calibration time for conventional probes in non-object measurement methods.

[0075] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0076] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A four-hole supersonic probe that does not require test calibration, characterized in that: The invention comprises a probe body (5) and a conical probe (6), wherein the probe body (5) is a seamless steel pipe having a bend at a position near the bottom end, wherein four channel tubes extending along with the probe body (5) are arranged at equal angles along the axis of the probe body (5) and are solidly welded to the probe body (5) at intervals therebetween, wherein the front edge of the probe body (5) is polished to form a conical probe (6) as a measuring end, wherein the four channel tubes are vertically connected to the generatrix of the conical probe (6) to form four hole positions including a No. 1 hole position (1), a No. 2 hole position (2), a No. 3 hole position (3) and a No. 4 hole position (4), wherein the four hole positions are all located at 50% of the generatrix of the conical probe (6), and wherein the aerodynamic parameters of the probe derived by the slender cone theory under supersonic conditions are as follows: Cone probe (6) zero angle of attack surface pressure coefficient distribution: The distribution of additional pressure coefficient of cone probe (6) at non-zero attack angle: The conversion relationship between pitch angle and yaw angle and circular angle and cone angle is: Pressure coefficient distribution of cone probe (6) at non-zero attack angle: C p =C p0 +ΔC p Substitute the pressure coefficient definition formula into The pressure distribution of the four holes is obtained: In the formula, δ represents the cutting angle at the location, γ represents the specific heat ratio of 1.4, α represents the yaw angle, β represents the pitch angle, and θ represents the cone angle. represents the circumference angle, represents the unified similarity parameter, represents the incoming flow density, R represents the thermodynamic constant, which is 8.314 J·mol -1 ·K -1 , T represents the static temperature of the incoming flow, V ∞ Indicates the incoming flow velocity, P ∞ Indicates the static pressure of the incoming flow; The idea of ​​partition calibration is to divide the probe into four areas according to the circular angle. The calibration formula is as follows: Calibration coefficient of airflow yaw angle α for each partition: Calibration coefficient of airflow pitch angle β for each partition: Total pressure calibration coefficient for each partition: Static pressure calibration coefficient for each zone: Where P n Indicates the hole with the highest pressure, K αn Indicates the n-zone yaw angle calibration coefficient, K βn represents the pitch angle calibration coefficient of zone n, C ptn Indicates the total pressure calibration coefficient of zone n, C psn Indicates the static pressure calibration coefficient of zone n, n = 1 to 4, corresponding to the circumferential angle interval Where: when n = 1, n-1 = 4, when n = 4, n+1 = 1, P t and P s Indicates the total pressure and static pressure of the incoming flow.

2. A four-hole supersonic probe that does not require test calibration according to claim 1, characterized in that: The semi-cone angle of the conical probe (6) is set to 15°.

Images