Flow loss measuring system of precooler connected in series with air inlet channel

Abstract

The invention discloses a flow loss measuring system for a precooler connected in series with an air inlet channel. The flow loss measuring system comprises a pressure adjusting section, an equipment spray pipe, an equal straight throat section, an expansion section, the precooler and a contraction section which are sequentially arranged in the airflow direction. The measuring system further comprises a plugging cone, a throttling plugging cone is arranged at an outlet of the precooler, and different compressor inlet pressure intensity working conditions are simulated; the temperature sensor is used for measuring the static temperature of an outlet of the precooler; the schlieren instrument is matched with the scale of the expansion section to determine an ending shock wave position; the total pressure rake and the static pressure rake are arranged at an outlet of the precooler and used for measuring the total pressure and the static pressure respectively, and the total pressure recovery coefficient of the precooler is obtained through calculation of all parameters, so that the total pressure loss when air in the precooling combined engine flows through the precooler can be quickly estimated under the incoming flow condition, and then reasonable layout design of the precooler of the air inlet channel is achieved. The design cost is reduced and the design efficiency is improved.

Description

Technical Field

[0001] The 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 take-off and landing, reusable hypersonic aircraft have important military and civilian value and are a hot topic in the current aerospace field. Hypersonic aircraft have high requirements for propulsion systems, and high-performance power systems are crucial for the development of hypersonic aircraft. The power system of a hypersonic aircraft must have the ability to accelerate from subsonic speed to supersonic speed and then to hypersonic speed. However, a single turbine, ramjet, or rocket power unit is difficult to operate in a wide speed range and wide airspace. To date, the existing hypersonic power system solutions include a variety of solutions, including a turboramjet combination engine, a rocket ramjet combination engine, a turboramjet rocket combination engine, and a pre-cooled combination engine.

[0003] Among them, the pre-cooling combined engine has received more attention in recent years; when a hypersonic aircraft flies at a high Mach number, the stagnation temperature of the incoming air is very high, far exceeding the tolerable range of the compressor blades, and the excessively high incoming temperature will make the air difficult to compress, and the engine performance will be greatly reduced. The use of intake precooling technology can improve the engine performance during hypersonic aircraft flight, improve the engine efficiency, and alleviate the thermal protection problems in the engine hot end and the intake passage, 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 temperature 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 is low when it flows through the precooler, which will cause greater losses. The drop in total air pressure will affect the 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 an 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] The Schlieren instrument is used to determine the position of the ending shock wave within the scale of the expansion section;

[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 inlet of the expansion section to the terminal shock wave and from the terminal shock wave to the inlet of the precooler.

[0013] Preferably, the expansion section area variation rule A is pre-designed diffuer =A(x), with a scale indicating the position, and the cross-sectional area A1 at the location 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 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 parameters before and after the normal shock wave:

[0018]

[0019] Then, by combining the flow continuity equation and flow function equation of the rear section A2 of the tail shock wave 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 precooling combination engine when it flows through the precooler can be quickly estimated under incoming flow conditions, thereby achieving a reasonable intake duct precooler 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 picture:

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

[0030] Figure 2 is an enlarged view of the measurement 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 embodiments of the present invention are described below in conjunction with the drawings in the embodiments of the present invention. The terms used in the implementation mode 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 embodiments of the present application are described below in conjunction with the 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, there are pressure regulating section 1, equipment nozzle 2, straight throat section 3, and the straight throat section is also equipped with a regulating valve 8, expansion section 4, precooler 5 and 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; and the flow from the expansion section inlet to the terminal shock wave and from the terminal shock wave to the precooler inlet is assumed to be a one-dimensional adiabatic isentropic flow;

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

[0037] The Schlieren instrument is used to determine the position of the ending shock wave within the scale of the expansion section;

[0038] Pre-design the expansion section area change law A diffuer =A(x), with a scale indicating the position, and the cross-sectional area A1 at the location 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 flow function equation at the inlet of 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 parameters before and after the normal shock wave:

[0043]

[0044] Then, by combining the flow continuity equation and flow function equation of the rear section A2 of the tail shock wave and the inlet section A3 of the precooler 5, 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 to obtain 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 embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. For ordinary technicians in this technical field, after knowing the contents recorded in the present invention, they can make several equivalent changes and substitutions without departing from the principle of the present invention. These equivalent changes and substitutions should also be regarded as belonging to the protection scope 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, an equal straight throat section, a precooler and a contraction section arranged in sequence according to the air flow 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; The Schlieren instrument is used to determine the position of the ending shock wave within the scale of the expansion section; 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.

2. The precooler flow loss measurement system arranged in series with the air intake duct according to claim 1, characterized in that: By adjusting the blocking cone, an end shock wave is made to exist in the expansion channel; and one-dimensional adiabatic isentropic flow is assumed from the inlet of the expansion section to the end shock wave and from the end shock wave to the inlet of the precooler.

3. The precooler flow loss measurement system arranged in series with the air intake duct according to claim 2, characterized in that: Pre-design the 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 front wave of the normal shock wave in the expansion section and the Mach number M3 of the precooler inlet are determined according to the flow conservation and the normal shock wave hypothesis: Among them, k is the specific heat ratio, A2 is the rear section of the ending shock wave, A3 is the precooler inlet section; M0 is the Mach number of the straight throat section and A0 is the cross-sectional area of ​​the straight throat section.

4. The precooler flow loss measurement system arranged in series with the air intake duct according to claim 3, 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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