A turbine-based ramjet combined engine and its design method

Abstract

The present application belongs to the technical field of turbine-based ramjet combination engine design, and specifically relates to a turbine-based ramjet combination engine and a design method thereof. The design is that a turbine engine and a subsonic ramjet engine are connected in parallel to share an air intake and an afterburner / ramjet combustion chamber, and combines the main advantages of a tandem turbine-based ramjet combination engine and a parallel turbine-based ramjet combination engine. Compared with a tandem turbine-based ramjet combination engine, when working in a ramjet engine mode, it can use a mode selection valve set at the inlet of a low-speed channel and a high-speed channel of the air inlet to close the low-speed channel of the air inlet, thereby achieving a closed and sealed turbine engine channel. It has good reliability and high efficiency at high Mach numbers. Compared with a parallel turbine-based ramjet combination engine, it reduces one set of ramjet combustion chambers and one combined nozzle channel, which can reduce the weight by 12% to 15%, can improve the aircraft mission payload and transonic performance, and reduce the control difficulty.

Description

Technical Field

[0001] The present application belongs to the technical field of turbine-based ramjet combination engine design, and specifically relates to a turbine-based ramjet combination engine and a design method thereof. Background Art

[0002] Turbine-ramjet engines are ideal propulsion systems for high-Mach-number spacecraft. The maximum operating Mach number is defined as Mach 5. Ramjets operating below Mach 5 use subsonic ramjets, while those above Mach 5 use dual-mode ramjets or scramjets. Currently, turbine-ramjet engines within Mach 5 primarily come in two configurations: tandem turbine-ramjet and parallel turbine-ramjet.

[0003] In a tandem turbine-ramjet combination, the turbine engine and ramjet are coaxially connected in series, sharing a common inlet, a common turbine engine afterburner, and a common ramjet (afterburner / ramjet), as well as a common nozzle. Airflow is compressed in a single-channel inlet and then split, with the central flow entering the turbine engine and the outer flow passing through an annular ramjet duct into the ramjet. After combustion in the turbine engine afterburner and ramjet, the airflow expands and is discharged through the nozzle. When operating in ramjet mode, a tandem turbine-ramjet combination has difficulty sealing the turbine engine ducts, resulting in poor reliability at high Mach numbers.

[0004] In a parallel turbo-ramjet combination engine, the turbine and ramjet are connected in parallel. Airflow is compressed through dual inlets before entering the turbine and ramjet engines, respectively, and then expanded and discharged through a dual-channel nozzle. This dual-channel arrangement makes the engine relatively tall and heavy, hindering the integrated flight and engine layout and resulting in poor maneuverability.

[0005] This application is proposed in view of the above-mentioned technical defects. Summary of the Invention

[0006] The purpose of this application is to provide a turbine-based ramjet combination engine and a design method thereof to overcome or alleviate at least one of the technical deficiencies of the known ones.

[0007] The technical solution of this application is:

[0008] A turbine-based ramjet combination engine, comprising a parallel combined air intake, a mode selection valve, an air intake low-speed passage, a turbine engine main engine, an air intake high-speed passage, a flow mixing device, an afterburner / ramjet combustion chamber, and a nozzle;

[0009] The inlets of the low-speed channel and the high-speed channel of the intake duct are connected to the outlet of the parallel-combined intake duct, and a mode selection valve is provided at the inlets of the low-speed channel and the high-speed channel of the intake duct. The mode selection valve can open or close the inlets of the low-speed channel and the high-speed channel of the intake duct, and adjust the relative opening of the inlets of the low-speed channel and the high-speed channel of the intake duct;

[0010] The main inlet of the turbine engine is connected to the outlet of the low-speed channel of the air inlet, and the low-speed channel of the air inlet, the main turbine engine and the high-speed channel of the air inlet are arranged in parallel;

[0011] The inlet of the mixing flow device is connected to the main engine of the turbine engine and the outlet of the high-speed channel of the air inlet;

[0012] The inlet of the afterburner / ramjet combustion chamber is connected to the outlet of the mixing flow device;

[0013] The nozzle is set at the outlet of the afterburner / ramjet combustion chamber.

[0014] According to at least one embodiment of the present application, the turbine-based ramjet combined engine has:

[0015] In turbine engine mode, the mode selection valve closes the inlet of the high-speed channel of the inlet duct;

[0016] In ramjet mode, the mode selection valve closes the inlet of the low-speed channel of the inlet;

[0017] In the intermediate conversion mode, the mode selection valve opens the inlet of the low-speed channel of the intake duct and the inlet of the high-speed channel of the intake duct.

[0018] According to at least one embodiment of the present application, in the above-mentioned turbine-based ramjet combination engine, the nozzle is a single-sided expansion nozzle.

[0019] According to at least one embodiment of the present application, in the above-mentioned turbine-based ramjet combination engine, the high-speed channel of the inlet is circular or elliptical;

[0020] The flow mixing device includes an internal high-speed channel and an internal low-speed channel, and the outlets of the internal high-speed channel and the internal low-speed channel are connected inside the flow mixing device and connected to the outlet of the flow mixing device;

[0021] The internal high-speed channel is an annular channel, and its inlet is connected to the outlet of the high-speed channel of the air inlet through a volute structure, serving as the outer duct of the afterburner / ramjet combustion chamber. The inlet of the internal low-speed channel is connected to the outlet of the turbine engine main engine, and a variable-area duct ejector structure is provided at the outlet of the internal high-speed channel.

[0022] A method for designing a turbine-based ramjet combination engine is provided, for designing the turbine-based ramjet combination engine, comprising:

[0023] Step 1: Task and requirements analysis:

[0024] Sort out aircraft requirements, clarify the power requirements and constraints of aircraft missions, and integrate upstream and downstream engine requirements and constraints to clarify the inputs for engine design;

[0025] Step 2: Thermodynamic cycle analysis:

[0026] Taking the turbine engine design point as the target and taking into account typical conditions, carry out turbine engine thermodynamic cycle parameter analysis;

[0027] Taking the design point of the ramjet engine as the target and taking into account the typical conditions, the thermodynamic cycle parameter analysis of the ramjet engine is carried out;

[0028] Step 3: Design point performance calculation:

[0029] Carry out design point performance calculations for turbine engines and sub-combustion ramjet engines;

[0030] Step 4: Main flow path design:

[0031] Design the main flow path of turbine engines and ramjet engines based on their design point performance and parameters;

[0032] Step 5. Typical state performance calculation:

[0033] Considering the aircraft requirements and the engine's own characteristics, calculate the typical state performance of the turbine engine and the sub-combustion ramjet engine. If the typical state performance does not meet the aircraft requirements, repeat steps 1 to 5.

[0034] Step 6: Combined intake flow split ratio design:

[0035] The common working range is clarified, requiring the total pressure at the outlet of the high-speed channel of the inlet duct Pcy2 to be greater than or equal to the static pressure at the outlet of the low-pressure turbine of the main engine of the turbine Ps6 or the static pressure at the outlet of the outer duct of the main engine of the turbine Ps16;

[0036] In response to the aircraft's power requirements, based on the performance of the turbine engine and sub-combustion ramjet within the common operating range, the combined intake flow is distributed. Combined with the performance calculation of the combined power common operating range, the split ratio is optimized to determine the optimal split ratio of the combined intake flow within the executable common operating range;

[0037] Step 7: Calculation of modal transition point performance:

[0038] Based on the optimal split ratio of the combined intake flow, the combined power, and the performance of each power unit within the executable common working range, the mode transition point is determined according to the inlet duct characteristics, the performance matching of the turbine engine and the sub-combustion ramjet engine within the mode transition range, the characteristics of the mixing flow device, and the characteristics of the afterburner / ramjet combustion chamber;

[0039] Based on the matching of the inlet characteristics and the characteristics of the turbine engine and the ramjet engine, calculate the modal transition point performance. If the modal transition point performance does not meet the aircraft requirements, repeat steps 1 to 7.

[0040] Step 8. Determine the design requirements of each component and system:

[0041] Based on the performance calculation results of turbine engines and ramjet engines at design points, typical states, and modal transition points, requirements for engine components and systems are proposed;

[0042] Step 9: Determine the overall performance concept plan:

[0043] The overall engine performance concept is formed by considering the aircraft mission's power requirements and constraints, the engine's upstream and downstream requirements and constraints, the turbine engine and ramjet engine's design points, typical state performance, and modal transition point performance. If the engine's overall performance does not meet the design requirements, repeat steps 1 to 9.

[0044] This application has at least the following beneficial technical effects:

[0045] Provided are a turbine-based ramjet combination engine and a design method thereof. The design employs a turbine engine and a subsonic ramjet engine with a parallel air intake and a shared afterburner / ramjet combustion chamber, combining the main advantages of a tandem turbine-based ramjet combination engine and a parallel turbine-based ramjet combination engine. Compared with the tandem turbine-based ramjet combination engine, when operating in ramjet engine mode, the low-speed inlet channel can be closed by setting mode selection valves at the inlets of the low-speed inlet channel and the high-speed inlet channel, thereby achieving a tight closure and sealing of the turbine engine channel. The engine has good reliability and high efficiency when operating at high Mach numbers. Compared with the parallel turbine-based ramjet combination engine, one set of ramjet combustion chambers and one combined nozzle channel are reduced, thereby reducing weight by 12% to 15%, thereby improving aircraft mission payload and transonic performance, and reducing control difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of a turbine-based ramjet combination engine provided in an embodiment of the present application;

[0047] Figure 2 It is a schematic diagram of the turbine-based ramjet combination engine design method provided in an embodiment of the present application.

[0048] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be understood as limiting this application. DETAILED DESCRIPTION

[0049] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0050] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should have the usual meanings understood by those skilled in the art in the field to which this application belongs. The words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application means that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0051] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0052] A turbine-based ramjet combination engine, such as Figure 1 As shown, it includes a parallel combined air intake, a mode selection valve, an air intake low-speed channel, a turbine engine main unit, an air intake high-speed channel, a mixing flow device, an afterburner / ramjet combustion chamber, and a nozzle.

[0053] The inlets of the low-speed channel and the high-speed channel of the intake duct are connected to the outlet of the intake duct in parallel. Mode selection valves are set at the inlets of the low-speed channel and the high-speed channel of the intake duct. The mode selection valves can open or close the inlets of the low-speed channel and the high-speed channel of the intake duct, and adjust the relative openings of the inlets of the low-speed channel and the high-speed channel of the intake duct.

[0054] The main inlet of the turbine engine is connected to the outlet of the low-speed channel of the air inlet, and the low-speed channel of the air inlet and the main turbine engine are located on the periphery of the high-speed channel of the air inlet.

[0055] The inlet of the mixing flow device is connected to the main engine of the turbine engine and the outlet of the high-speed channel of the air inlet.

[0056] The inlet of the afterburner / ramjet combustion chamber is connected to the outlet of the mixing flow device.

[0057] The nozzle can specifically adopt a single-sided expansion nozzle, which is arranged at the outlet of the afterburner / ramjet combustion chamber.

[0058] The turbine-based ramjet combination engine disclosed in the above embodiment has a turbine engine mode, a ramjet engine mode, and an intermediate conversion mode.

[0059] In turbine engine mode, the mode selector valve closes the inlet of the high-speed inlet channel. Air flows through the parallel combined inlet and the low-speed inlet channel into the turbine engine main engine for combustion. Air then flows through the mixing flow device into the afterburner / ramjet combustor for supplementary combustion, and is discharged through the nozzle. This turbine engine mode is suitable for low Mach number flight, Mach 0 to Mach 2.

[0060] In ramjet mode, the mode selector valve closes the low-speed inlet channel. Air flows through the parallel combined inlet and high-speed inlet channels into the mixing flow device, then into the afterburner / ramjet combustor for combustion, expanding and exhausting through the nozzle. Ramjet mode is suitable for high Mach number flight, Mach 3 to Mach 5.

[0061] In the intermediate transition mode, the mode selector valve opens the inlets of the low-speed and high-speed inlet channels. Airflow enters the parallel combined inlet ducts, then passes through the low-speed inlet channel to the turbine engine main engine for combustion before entering the mixing flow device. It then passes through the high-speed inlet channel to the mixing flow device, where it mixes and enters the afterburner / ramjet combustor for combustion, before expanding and being discharged through the nozzle. The intermediate transition mode is suitable for flight between low and high Mach numbers, from Mach 2 to Mach 3.

[0062] Taking into account factors such as the integrated layout with the turbine engine main engine, the high-speed channel of the air inlet can be designed to be circular, elliptical or even irregular in shape.

[0063] The mixing flow device includes an internal high-speed channel and an internal low-speed channel. The outlets of the internal high-speed channel and the internal low-speed channel are connected within the mixing flow device and connected to the outlet of the mixing flow device. The internal high-speed channel is an annular channel. Its inlet is connected to the outlet of the high-speed channel of the intake duct through a volute structure, serving as the outer duct inlet of the afterburner / ramjet combustion chamber. The inlet of the internal low-speed channel is connected to the outlet of the turbine engine. A variable-area duct ejector structure is installed at the outlet of the internal high-speed channel to adjust the static pressure of the exhaust gas of the internal high-speed channel and the internal low-speed channel, and to balance the static pressure of the exhaust gas of the low-pressure turbine of the turbine engine and the exhaust gas of the outer duct inlet.

[0064] The turbine-based ramjet combination engine disclosed in the above embodiment is designed to have a turbine engine and a subsonic ramjet engine connected in parallel with a shared afterburner / ramjet combustion chamber, combining the main advantages of a tandem turbine-based ramjet combination engine and a parallel turbine-based ramjet combination engine. Compared to a tandem turbine-based ramjet combination engine, when operating in ramjet mode, the low-speed inlet passage can be closed by means of mode selection valves provided at the inlets of the low-speed inlet passage and the high-speed inlet passage, thereby achieving a tight closure and sealing of the turbine engine passage. It has good reliability and high efficiency at high Mach numbers. Compared to a parallel turbine-based ramjet combination engine, one ramjet combustion chamber and one combined nozzle passage are omitted, resulting in a weight reduction of 12% to 15%, which can improve the aircraft's mission payload and transonic performance, and reduce control difficulty.

[0065] A method for designing a turbine-based ramjet combination engine is used to design the turbine-based ramjet combination engine disclosed in the above embodiment, such as Figure 2 shown.

[0066] Step 1: Task and requirements analysis.

[0067] Sort out aircraft requirements, clarify the power requirements and constraints of aircraft missions, and integrate upstream and downstream engine requirements and constraints to clarify the input of engine design.

[0068] Step 2: Thermal cycle analysis.

[0069] Taking the turbine engine design point as the target and taking into account typical conditions, the analysis of thermodynamic cycle parameters such as turbine engine compression ratio, turbine pre-turbine temperature, afterburner temperature, etc. is carried out. Factors such as component technology, material process limitations, temperature constraints, cooling type and cooling air volume coefficient need to be considered.

[0070] Taking the design point of the subsonic ramjet engine as the target and taking into account the typical conditions, the analysis of thermodynamic cycle parameters such as the total pressure recovery coefficient and flow coefficient of the subsonic ramjet engine inlet, the combustion efficiency and outlet temperature of the ramjet combustion chamber, the nozzle thrust coefficient and expansion ratio is carried out. Factors such as component technology, temperature constraints and cold air volume coefficient need to be considered.

[0071] Step 3: Calculate design point performance.

[0072] Carry out design point performance calculations for turbine engines and sub-combustion ramjet engines.

[0073] Step 4: Main flow path design.

[0074] Based on the design point performance and parameters of turbine engines and sub-steam ramjet engines, the main flow paths of turbine engines and sub-steam ramjet engines are designed.

[0075] Step 5: Calculate the performance under typical conditions.

[0076] Considering the aircraft requirements and the engine's own characteristics, calculate the typical state performance of the turbine engine and sub-combustion ramjet engine. If the typical state performance does not meet the aircraft requirements, repeat steps 1 to 5.

[0077] Step 6: Design the combined intake flow split ratio.

[0078] The executable common working range is clearly defined, requiring that the total pressure Pcy2 at the outlet of the high-speed channel of the inlet duct is greater than or equal to the static pressure Ps6 at the outlet of the low-pressure turbine of the main engine of the turbine or the static pressure Ps16 at the outlet of the outer duct of the main engine of the turbine.

[0079] In response to the aircraft's power requirements, the combined intake flow is distributed based on the performance of the turbine engine and sub-combustion ramjet engine in the common working range. Combined with the performance calculation of the combined power common working range, the split ratio is optimized to determine the optimal split ratio of the combined intake flow in the executable common working range.

[0080] Step 7: Calculate the performance of the modal transition point.

[0081] Based on the optimal split ratio of the combined intake flow, the combined power and the performance of each power unit within the executable common working range, the modal transition point is determined according to the inlet duct characteristics, the performance matching of the turbine engine and the sub-combustion ramjet engine in the modal transition range, the characteristics of the mixing flow device, and the characteristics of the afterburner / ramjet combustion chamber.

[0082] Based on the matching of the inlet characteristics and the characteristics of the turbine engine and the ramjet engine, calculate the modal transition point performance. If the modal transition point performance does not meet the aircraft requirements, repeat steps 1 to 7.

[0083] Step 8. Determine the design requirements of each component and system.

[0084] Based on the performance calculation results of the design points, typical states and modal transition points of turbine engines and sub-species combustion ramjet engines, requirements for various engine components and systems are proposed.

[0085] Step 9: Determine the overall performance concept plan.

[0086] The overall engine performance concept is formed by considering the aircraft mission's power requirements and constraints, the engine's upstream and downstream requirements and constraints, the turbine engine and ramjet engine's design points, typical state performance, and modal transition point performance. If the engine's overall performance does not meet the design requirements, repeat steps 1 to 9.

[0087] The above embodiments disclosed

[0088] The turbine-based ramjet combination engine design method disclosed in the above embodiment is used to design the turbine-based ramjet combination engine disclosed in the above embodiment. The description is relatively simple. For specific related matters, please refer to the relevant description of the turbine-based ramjet combination engine part. Its technical effects can also refer to the technical effects of the relevant parts of the turbine-based ramjet combination engine, and will not be repeated here.

[0089] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for designing a turbine-based ramjet combination engine, comprising a parallel combination inlet, a mode selection valve, a low-speed inlet passage, a turbine engine main engine, a high-speed inlet passage, a flow mixing device, an afterburner / ramjet combustion chamber, and a nozzle; The inlets of the low-speed channel and the high-speed channel of the intake duct are connected to the outlet of the parallel-combined intake duct, and a mode selection valve is provided at the inlets of the low-speed channel and the high-speed channel of the intake duct. The mode selection valve can open or close the inlets of the low-speed channel and the high-speed channel of the intake duct, and adjust the relative opening of the inlets of the low-speed channel and the high-speed channel of the intake duct; The main inlet of the turbine engine is connected to the outlet of the low-speed channel of the air inlet, and the low-speed channel of the air inlet, the main turbine engine and the high-speed channel of the air inlet are arranged in parallel; The inlet of the mixing flow device is connected to the main engine of the turbine engine and the outlet of the high-speed channel of the air inlet; The inlet of the afterburner / ramjet combustion chamber is connected to the outlet of the mixing flow device; The nozzle is arranged at the outlet of the afterburner / ramjet combustion chamber; The turbine-based ramjet engine design method is characterized by comprising: Step 1: Task and requirements analysis: Sort out aircraft requirements, clarify the power requirements and constraints of aircraft missions, and integrate upstream and downstream engine requirements and constraints to clarify the inputs for engine design; Step 2: Thermodynamic cycle analysis: Taking the turbine engine design point as the target and taking into account typical conditions, carry out turbine engine thermodynamic cycle parameter analysis; Taking the design point of the ramjet engine as the target and taking into account the typical conditions, the thermodynamic cycle parameter analysis of the ramjet engine is carried out; Step 3: Design point performance calculation: Carry out design point performance calculations for turbine engines and sub-combustion ramjet engines; Step 4: Main flow path design: Design the main flow path of turbine engines and ramjet engines based on their design point performance and parameters; Step 5. Typical state performance calculation: Considering the aircraft requirements and the engine's own characteristics, calculate the typical state performance of the turbine engine and the sub-combustion ramjet engine. If the typical state performance does not meet the aircraft requirements, repeat steps 1 to 5. Step 6: Combined intake flow split ratio design: The common working range is clarified, requiring the total pressure at the outlet of the high-speed channel of the inlet duct Pcy2 to be greater than or equal to the static pressure at the outlet of the low-pressure turbine of the main engine of the turbine Ps6 or the static pressure at the outlet of the outer duct of the main engine of the turbine Ps16; In response to the aircraft's power requirements, based on the performance of the turbine engine and sub-combustion ramjet within the common operating range, the combined intake flow is distributed. Combined with the performance calculation of the combined power common operating range, the split ratio is optimized to determine the optimal split ratio of the combined intake flow within the executable common operating range; Step 7: Calculation of modal transition point performance: Based on the optimal split ratio of the combined intake flow, the combined power, and the performance of each power unit within the executable common working range, the mode transition point is determined according to the inlet duct characteristics, the performance matching of the turbine engine and the sub-combustion ramjet engine within the mode transition range, the characteristics of the mixing flow device, and the characteristics of the afterburner / ramjet combustion chamber; Calculate the modal transition point performance based on the inlet characteristics and the matching characteristics of the turbine engine and the ramjet engine. If the modal transition point performance does not meet the aircraft requirements, repeat steps 1 to 7. Step 8. Determine the design requirements of each component and system: Based on the performance calculation results of turbine engines and ramjet engines at design points, typical states, and modal transition points, requirements for engine components and systems are proposed; Step 9: Determine the overall performance concept plan: Consider the aircraft mission's power requirements and constraints, the engine's upstream and downstream requirements and constraints, the turbine engine and ramjet engine's design points, typical state performance, and modal transition point performance to form a conceptual plan for the engine's overall performance. If the engine's overall performance does not meet the design requirements, repeat steps one through nine.

2. The method for designing a turbine-based ramjet engine according to claim 1, characterized in that: A turbo-ramjet combination engine with: In turbine engine mode, the mode selection valve closes the inlet of the high-speed channel of the inlet duct; In ramjet mode, the mode selection valve closes the inlet of the low-speed channel of the inlet; In the intermediate conversion mode, the mode selection valve opens the inlet of the low-speed channel of the intake duct and the inlet of the high-speed channel of the intake duct.

3. The method for designing a turbine-based ramjet engine according to claim 1, characterized in that: In the turbine-based ramjet combination engine, the nozzle is a single-sided expansion nozzle.

4. The method for designing a turbine-based ramjet engine according to claim 1, wherein: In a turbine-based ramjet combination engine, the high-speed channel of the inlet is circular or elliptical; The flow mixing device includes an internal high-speed channel and an internal low-speed channel, and the outlets of the internal high-speed channel and the internal low-speed channel are connected inside the flow mixing device and connected to the outlet of the flow mixing device; The internal high-speed channel is an annular channel, and its inlet is connected to the outlet of the high-speed channel of the air inlet through a volute structure, serving as the outer duct of the afterburner / ramjet combustion chamber. The inlet of the internal low-speed channel is connected to the outlet of the turbine engine main engine, and a variable-area duct ejector structure is provided at the outlet of the internal high-speed channel.

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