A flow loss measurement system for a precooler arranged in series with the air intake duct

Abstract

The present invention discloses a precooler flow loss measurement system arranged in series with an air inlet duct, comprising a pressure regulating section, an equipment nozzle, a straight throat section, an expansion section, a precooler and a contraction section arranged in sequence according to the direction of airflow; the measurement system also comprises: a blocking cone, a throttling blocking cone is arranged at the outlet of the precooler to simulate different compressor inlet pressure working conditions; a temperature sensor, measuring the static temperature at the outlet of the precooler; a schlieren instrument, cooperating with the scale of the expansion section to determine the position of the end shock wave; a total pressure rake and a static pressure rake, arranged at the outlet of the precooler, respectively used to measure the total pressure and static pressure, and the total pressure recovery coefficient of the precooler is obtained by calculating the various parameters, so that the total pressure loss of the air in the precooling combination engine when flowing through the precooler can be quickly estimated under the condition of incoming flow, thereby realizing a reasonable layout design of the inlet duct precooler, reducing the design cost and improving the design efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of hypersonic combined power heat exchange precooling, and in particular to a precooler flow loss measurement system arranged in series with an air inlet. Background Art

[0002] Horizontal takeoff and landing, reusable hypersonic aircraft have significant military and civilian applications and are a current research hotspot in the aerospace field. Hypersonic aircraft place high demands on their propulsion systems, and high-performance power systems are crucial for their development. Hypersonic aircraft propulsion systems must be able to accelerate from subsonic to supersonic and then to hypersonic speeds. However, single turbine, ramjet, or rocket propulsion systems struggle to operate across a wide range of speeds and airspaces. Existing hypersonic propulsion system solutions include turboramjet, rocket-ramjet, turboramjet-rocket, and pre-cooled engines.

[0003] Among them, pre-cooling combined engines have received more attention in recent years; when hypersonic aircraft fly at high Mach numbers, the stagnation temperature of the incoming air is very high, far exceeding the tolerable range of the compressor blades, and the excessively high incoming air temperature will make the air difficult to compress, and the engine performance will be greatly reduced. The use of intake pre-cooling technology can improve the engine performance during hypersonic aircraft flight, improve engine efficiency, and alleviate thermal protection problems in the engine hot end and intake channel, which is of great significance for expanding the aircraft flight envelope and improving the engine thrust-to-weight ratio.

[0004] The precooler cools the high-temperature airflow captured by the inlet duct to avoid excessively high airflow temperatures in front of the compressor under high Mach number inlet conditions. However, due to the addition of the precooler, the total pressure recovery coefficient of the air flowing through the precooler is low, which will cause large losses. The drop in total air pressure will affect engine performance. Therefore, a precooler flow loss measurement system arranged in series with the inlet duct is proposed to measure the flow loss of the precooler, so as to shorten the design time of the precooling inlet duct in a shorter time. Summary of the Invention

[0005] The purpose of the present invention is to provide a precooler flow loss measurement system arranged in series with the air intake duct, which can effectively solve the problems existing in the above-mentioned prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: a precooler flow loss measurement system arranged in series with the air inlet duct, comprising a pressure regulating section, an equipment nozzle, a straight throat section, a precooler and a contraction section arranged in sequence according to the air flow direction; the measurement system is provided with an expansion section, which is located between the straight throat section and the precooler, and

[0007] Also includes:

[0008] Blocking cone: a throttling blocking cone is set at the outlet of the precooler to simulate different compressor inlet pressure conditions;

[0009] A temperature sensor, for measuring the static temperature at the outlet of the precooler;

[0010] Schlieren instrument, used in conjunction with the scale of the expansion section to determine the position of the ending shock wave;

[0011] The total pressure rake and static pressure rake are arranged at the outlet of the precooler and are used to measure the total pressure and static pressure respectively.

[0012] Preferably, by adjusting the blocking cone, a terminal shock wave is created in the expansion channel; and one-dimensional adiabatic isentropic flow is assumed from the expansion section inlet to the terminal shock wave and from the terminal shock wave to the precooler inlet.

[0013] Preferably, the expansion section area change rule A is pre-designed diffuer =A(x), with a scale indicating the position, and the cross-sectional area A1 of the end shock wave is determined by the schlieren;

[0014] The Mach number M1 of the terminal shock wave front can be obtained by combining the flow continuity equation and the flow function equation at the inlet of the expansion section:

[0015]

[0016] M0 is the Mach number of the straight throat section and A0 is the cross-sectional area of ​​the straight throat section, k is the specific heat ratio;

[0017] The Mach number M2 of the airflow behind the normal shock wave is determined by the relationship between the front and rear parameters of the normal shock wave:

[0018]

[0019] Then, by combining the flow continuity equation and flow function equation of the tail shock wave rear section A2 and the precooler inlet section A3, the precooler inlet Mach number M3 can be obtained:

[0020]

[0021] Preferably, a total pressure rake and a static pressure rake are arranged at the outlet of the precooler to measure the total pressure and static pressure of the outlet airflow, and convert the outlet Mach number; and the outlet airflow static temperature T4 is measured based on the temperature sensor, and the total temperature is calculated by the following formula:

[0022]

[0023] The total pressure recovery coefficient is:

[0024]

[0025] in, is the total temperature at the expansion section inlet, A4 is the precooler outlet area, and M4 is the precooler outlet Mach number; M4 is the precooler outlet Mach number, which is obtained by measuring the total pressure rake and static pressure rake at the precooler outlet.

[0026] Beneficial effect: Through the measurement system of the present invention, the total pressure loss of air in the pre-cooling combination engine when it flows through the pre-cooler can be quickly estimated under incoming flow conditions, thereby achieving a reasonable intake duct pre-cooler layout design, reducing design costs and improving design efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0028] In the attached figure:

[0029] Figure 1 It is a diagram of the measurement system of the present invention;

[0030] Figure 2 It is an enlarged view of the measuring system of the present invention;

[0031] Numbers in the figure: 1. Pressure regulating section; 2. Equipment nozzle; 3. Straight throat section; 4. Expansion section; 5. Precooler; 6. Contraction section; 7. Blocking cone; 8. Control valve. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention in conjunction with the accompanying drawings. The terms used in the embodiments of the present invention are only used to explain the specific embodiments of the present invention and are not intended to limit the present invention. The following describes the embodiments of the present application in conjunction with the accompanying drawings.

[0033] like Figure 1-Figure 2 As shown, a precooler flow loss measurement system arranged in series with the air inlet duct includes: Figure 1 From left to right, the pressure regulating section 1, the equipment nozzle 2, and the straight throat section 3 are arranged. The straight throat section is also equipped with a regulating valve 8, an expansion section 4, a precooler 5, and a contraction section 6. The measurement system also includes:

[0034] Blocking cone 7, a throttling blocking cone is set at the outlet of the precooler to simulate different compressor inlet pressure conditions;

[0035] By adjusting the blocking cone, a terminal shock wave is created in the expansion channel. One-dimensional adiabatic isentropic flow is assumed from the expansion section inlet to the terminal shock wave and from the terminal shock wave to the precooler inlet.

[0036] Temperature sensor, measuring the static temperature at the outlet of precooler 5;

[0037] Schlieren instrument, used in conjunction with the scale of the expansion section to determine the position of the ending shock wave;

[0038] Pre-designed expansion section area change law A diffuer =A(x), with a scale indicating the position, and the cross-sectional area A1 of the end shock wave is determined by the schlieren;

[0039] The Mach number M1 of the terminal shock wave front can be obtained by combining the flow continuity equation and the flow function equation at the inlet of the expansion section 4:

[0040]

[0041] k is the specific heat ratio, which is taken as 1.4 for air, M0 is the Mach number of the straight throat section, and A0 is the cross-sectional area of ​​the straight throat section;

[0042] The Mach number M2 of the airflow behind the normal shock wave is determined by the relationship between the front and rear parameters of the normal shock wave:

[0043]

[0044] Then, by combining the flow continuity equation and flow function equation of the tail shock wave rear section A2 and the precooler 5 inlet section A3, the precooler 5 inlet Mach number M3 can be obtained:

[0045]

[0046] The total pressure rake and static pressure rake are arranged at the outlet of the precooler 5 to measure the total pressure and static pressure of the outlet airflow and convert them into the outlet Mach number; and based on the temperature sensor, the outlet airflow static temperature T4 is measured and the total temperature is calculated by the following formula

[0047]

[0048] The total pressure recovery coefficient is:

[0049]

[0050] in, is the total temperature at the inlet of expansion section 4, A4 is the outlet area of ​​precooler 5, and M4 is the Mach number at the outlet of precooler 5. M4 is the Mach number at the outlet of precooler 5, which is obtained by measuring the total pressure rake and static pressure rake at the outlet of precooler 5.

[0051] The above describes the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. After knowing the contents described in the present invention, ordinary technicians in this technical field can make several equivalent changes and substitutions without departing from the principles of the present invention. These equivalent changes and substitutions should also be regarded as falling within the scope of protection of the present invention.

Claims

1. A precooler flow loss measurement system arranged in series with an air inlet duct, comprising a pressure regulating section, an equipment nozzle, a straight throat section, a precooler, and a contraction section arranged in sequence according to the airflow direction; characterized in that: The measuring system is provided with an expansion section located between the straight throat section and the precooler, and Also includes: Blocking cone: a throttling blocking cone is set at the outlet of the precooler to simulate different compressor inlet pressure conditions; A temperature sensor, for measuring the static temperature at the outlet of the precooler; Schlieren instrument, used in conjunction with the scale of the expansion section to determine the position of the ending shock wave; Total pressure rake and static pressure rake are arranged at the outlet of precooler and are used to measure total pressure and static pressure respectively; By adjusting the blocking cone, a terminal shock wave is created in the expansion channel; and one-dimensional adiabatic isentropic flow is assumed from the expansion section inlet to the terminal shock wave and from the terminal shock wave to the precooler inlet.

2. The precooler flow loss measurement system arranged in series with the air intake duct according to claim 1, characterized in that: Pre-designed expansion section area change law A diffuer =A(x), with a scale indicating the position, and the cross-sectional area A1 of the end shock wave is determined by the schlieren; the Mach numbers M1 and M2 after the normal shock wave front in the expansion section and the Mach number M3 at the precooler inlet are determined based on the flow conservation law and the normal shock wave hypothesis: Where k is the specific heat ratio, A2 is the rear cross section of the tail shock wave, A3 is the precooler inlet cross section; M0 is the Mach number of the straight throat section and A0 is the cross-sectional area of ​​the straight throat section.

3. The precooler flow loss measurement system arranged in series with the air intake duct according to claim 2, characterized in that: By arranging a total pressure rake and a static pressure rake at the outlet of the precooler, the total pressure and static pressure of the outlet airflow are measured and the outlet Mach number is obtained by conversion; and the outlet airflow static temperature T4 is measured based on the temperature sensor, and the total temperature is calculated by the following formula And the total pressure recovery coefficient of the precooler is determined according to the following formula: in, is the total temperature at the expansion section inlet, A4 is the precooler outlet area, and M4 is the precooler outlet Mach number; M4 is the precooler outlet Mach number, which is obtained by measuring the total pressure rake and static pressure rake at the precooler outlet.

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