Wide-speed-range integrated series TBCC inlet and its internal contraction ratio control method

Abstract

The present invention discloses a wide-speed-range integrated series TBCC inlet and its internal contraction ratio control method. The inlet includes a center cone, a movable throat, a ram channel, and a turbine channel. Among them, both ends of the center cone are pointed and the middle part is thick. The maximum outer diameter of the middle part is located at the lip of the inlet. Half of the center cone is located inside the inlet and half is located outside it. The front end of the inlet is the lip, and behind the lip is the ram channel. Inside the inlet, outside the center cone is the turbine channel. A movable throat is provided between the turbine channel and the ram channel, and functions such as controlling the internal contraction ratio of the axisymmetric series TBCC inlet, flow rate regulation, and flow path switching during the mode conversion process are achieved through the forward and backward movement of the throat. At low speeds, the internal contraction ratio of the inlet is relatively small, and the air flow mainly enters the turbine channel, and the ram channel is a bypass. At high speeds, the internal contraction ratio of the inlet increases, and the air flow mainly enters the ram channel. The turbine channel is a bypass and overflows the boundary layer developed from the center cone, thereby improving the starting characteristics of the inlet.

Description

Technical Field

[0001] The present invention relates to a design of a tandem TBCC inlet, belonging to the research field of combined power inlets. Background Art

[0002] Scramjet-powered hypersonic vehicles have strong penetration capabilities, high specific impulse, can take off and land horizontally, and can be reused. Currently, the thrust of most flight devices flying in the atmosphere is provided by jet engines. In different Mach number ranges, various scramjet engines have different specific impulses. When the Mach number of a turbojet engine is greater than 3, its efficiency will drop sharply, and it is difficult for the turbojet engine to be used as the power source of the vehicle again. At this time, the ramjet engine with poor performance at low Mach numbers can efficiently compress the oncoming flow through high-speed air ramming. Therefore, if we want to meet the thrust requirements of the vehicle at the entire operating Mach number and have high efficiency, the combined power engine is a solution with good application prospects.

[0003] In order to enable the engine to work in a wider range with better performance and meet the requirements of self-acceleration and reusability of hypersonic flight devices, researchers have proposed various combined cycle power systems such as air turbine rocket / ramjet combined cycle engines (ATR), turbine-based combined cycle engines (TBCC), and rocket-based combined cycle engines (RBCC), and a large amount of research work has been carried out around these combined engines. Among them, the TBCC engine is an organic integration of a turbofan / turbojet engine and a ramjet engine. During the takeoff phase, the engine operates in the turbofan / turbojet mode. During the mode transition phase, the ramjet engine and the turbofan / turbojet engine work together. As the flight Mach number increases, the inlet of the turbine engine gradually closes. When the Mach number reaches a certain condition, the turbine engine stops operating and the ramjet engine starts to work.

[0004] First of all, the combined power engine requires its inlet to work efficiently and stably in a wide airspace and wide speed range, including having good total pressure recovery ability and anti-backpressure ability when operating in a wide Mach number range, having a high flow coefficient in the operating range, and having good performance at low Mach numbers. Secondly, with the continuous development of aeroengine control systems, as an important component of an aeroengine, inlet control technology is indispensable. To achieve the stable and efficient operation of the engine, it is necessary to achieve a good match between the inlet and the engine flow. It can be seen that the performance of the combined power engine inlet is very crucial to the engine. Improving the applicability and aerodynamic performance of the inlet under different flight conditions is recognized internationally as the key to the development of combined power engines. Therefore, it is necessary to design a reasonable variable geometry and mode conversion scheme for the TBCC inlet to achieve stable operation of the inlet in a wide speed range. Summary of the Invention

[0005] It is difficult to vary the geometry of an axisymmetric inlet. Usually, the geometry adjustment of an axisymmetric inlet is achieved by moving the center cone and the cowl. The present invention proposes a method of moving the throat to achieve functions such as internal contraction ratio control, flow rate adjustment, and flow path switching during mode conversion in an axisymmetric TBCC inlet at different flight states.

[0006] This application is for a wide-speed-range integrated series TBCC inlet. The inlet includes a center cone, a movable throat, a ram channel, and a turbine channel. Among them, both ends of the center cone are pointed and the middle part is thick. The maximum outer diameter at the middle part is located at the cowl of the inlet. Half of the center cone is inside the inlet and half is outside it. The front end of the inlet is the cowl, and behind the cowl is the ram channel. Inside the inlet, outside the center cone is the turbine channel, and a movable throat is provided between the turbine channel and the ram channel.

[0007] Further, the movable throat is located at the front end of the turbine channel and is sleeved outside the turbine channel for moving along the axis of the center cone outside the center cone.

[0008] Further, the length of the ram channel is less than half of the length of the center cone.

[0009] Further, the outer profile of the movable throat is designed with a spline curve. The outer diameter in the middle is large and the outer diameters at both ends are small. The middle part of the movable throat is a hollow channel along the axial direction. After the fluid enters the channel, it then enters the turbine channel.

[0010] Further, the inner diameter of the inlet is large near the cowl position and small at the rear ram channel. Its inner profile cooperates with the outer profile of the movable throat. The maximum outer diameter of the movable throat moves along the axis towards the cowl until it abuts against the inner wall of the inlet, and moves in the reverse direction until the inner diameter of the movable throat abuts against the outer diameter of the turbine channel.

[0011] Based on the above integrated series TBCC inlet, this application also provides a method for controlling its internal contraction ratio. The engine rotor speed signal and the inlet temperature signal are collected to obtain the command signal adjustment voltage U of the movable throat in , which is compared with the feedback signal U of the movable throat back to form a differential voltage ΔU. After being amplified by a servo amplifier and converted from voltage to current, a driving current is generated to control the electro-hydraulic servo valve to act on the hydraulic cylinder, thereby changing the horizontal position of the movable throat and adjusting the internal contraction ratio of the inlet.

[0012] The beneficial effects of the present invention are:

[0013] Adopting this solution can achieve the control of the internal contraction ratio, thereby broadening the working range of the axisymmetric TBCC inlet and completing the flow regulation during the mode conversion process and the switching between high- and low-speed channels. Brief Description of the Drawings

[0014] The present invention will be further described below in conjunction with the drawings and examples:

[0015] Figure 1 It is a schematic diagram of a turbine-mode series TBCC inlet;

[0016] Figure 2 It is a schematic diagram of a series TBCC inlet during the mode conversion process;

[0017] Figure 3 It is a schematic diagram of a ram-mode series TBCC inlet;

[0018] Figure 4 It is a schematic diagram of the structure of the inlet regulation control system;

[0019] Figure 5 It is a simulation model of the inlet regulation system based on Simulink;

[0020] Figure 6 It is a schematic diagram of the flow coefficient of the main channel and bypass channel of the series TBCC inlet;

[0021] Figure 7 It is a schematic diagram of the step input and dynamic response curve of the inlet throat position from 0 to 100%;

[0022] The meanings of the horizontal and vertical coordinates and the icons in the figure are as follows:

[0023] Ma: Mach number;

[0024] Flow coefficient;

[0025] Bypass flow coefficient;

[0026] Reference numerals in the figure: 1 - center cone, 2 - lip, 3 - movable throat, 4 - ram channel, 5 - turbine channel. Detailed Embodiments

[0027] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0028] The present invention aims at an axisymmetric series TBCC integrated inlet, and proposes a design idea and method for a movable throat, so as to realize functions such as contraction ratio control, flow regulation and flow path switching in the modal conversion process in the inlet. First, according to the conical flow theory, a fixed-geometry axisymmetric inlet is designed, and a reasonable design point is selected to balance the performance at the design point and off-design points; secondly, according to the characteristics of the TBCC engine, a turbine / ramjet channel and a movable throat are designed, and the functions such as contraction ratio control, flow regulation and flow path switching in the modal conversion process in the axisymmetric series TBCC inlet are realized by moving the throat back and forth. The upper and lower profiles of the movable throat are designed with spline curves to match the inner profile of the turbine channel and the outer profile of the ramjet channel.

[0029] This application is for a wide-speed-range integrated series TBCC inlet. The inlet includes a center cone, a movable throat, a ramjet channel and a turbine channel; wherein, both ends of the center cone are pointed and the middle part is thick, and the maximum outer diameter at the middle part is located at the lip of the inlet. Half of the center cone is located inside the inlet and half is located outside it; the front end of the inlet is the lip, and behind the lip is the ramjet channel; inside the inlet, outside the center cone is the turbine channel, and a movable throat is arranged between the turbine channel and the ramjet channel.

[0030] Further, the movable throat is located at the front end of the turbine channel and is sleeved outside the turbine channel for moving along the axis of the center cone outside the center cone.

[0031] Further, the length of the ramjet channel is less than half of the length of the center cone.

[0032] Further, the outer profile of the movable throat is designed with spline curves, the outer diameter in the middle is large, and the outer diameters at both ends are small. The middle of the movable throat is a hollow channel along the axial direction, and the fluid enters the channel and then enters the turbine channel.

[0033] Further, the inner diameter of the inlet is large near the lip position and small at the inner diameter of the rear ramjet channel, and its inner profile matches the outer profile of the movable throat; the maximum outer diameter of the movable throat moves along the axis towards the lip direction until it abuts against the inner wall of the inlet, and moves in the reverse direction until the inner diameter of the movable throat abuts against the outer diameter of the turbine channel.

[0034] Embodiment 1

[0035] As Figures 1 to 3As shown in the figure, the axisymmetric series TBCC inlet includes a center cone 1, a lip 2, a movable throat 3, a ram channel 4, and a turbine channel 5. Among them, the total length of the center cone 1 is 7.37 m and it is located at the lip 2 of the inlet. The diameter of the lip 2 is 1.75 m. The center cone 1 has a structure with pointed ends and a thick middle part. Its middle part is located at the lip 2, with half inside the inlet and half outside it. The front end of the inlet is the lip 2, and the rear end is the ram channel 4 with a length of 3.60 m. Inside the inlet, outside the center cone is the turbine channel 5 with a length of 3.60 m. A movable throat 3 with a length of 0.90 m is provided between the turbine channel 5 and the ram channel 4. The movable throat 3 is sleeved outside the turbine channel 5 and can move along the axis with a moving distance of 0.90 m. The upper surface of the movable throat 3 is designed with a spline curve to cooperate with the inner surface of the inlet lip 2, so as to realize the functions of controlling the internal contraction ratio in the inlet, regulating the flow rate, and switching the flow path during the mode conversion process. The lower surface of the movable throat 3 is designed to cooperate with the surface of the turbine channel 5, so as to realize the functions of regulating the flow rate in the inlet and switching the flow path during the mode conversion process.

[0036] When the series TBCC inlet operates at low speed, it needs to provide the required flow rate for the turbine engine. At the same time, during low-speed flight, the allowable internal contraction ratio of the inlet is relatively low. As the incoming flow Mach number increases, the series TBCC inlet switches to the ram mode. Therefore, the inlet needs to provide the required flow rate for the ram engine. At the same time, as the incoming flow Mach number increases, the allowable internal contraction ratio for the stable operation of the inlet increases. For the aeroengine control system, the inlet switching from the low-speed state to the ram mode is a transition state - steady state process. When the inlet is in the turbine mode, it corresponds to the takeoff stage of the engine. When the inlet is in the ram mode, it corresponds to the cruise stage of the engine. Therefore, in order to take into account the high and low-speed characteristics of the series TBCC inlet, an axisymmetric inlet with a controllable internal contraction ratio, capable of flow rate regulation and flow path switching for mode conversion, needs to be designed.

[0037] Embodiment 2

[0038] Based on the above integrated series TBCC inlet, the present application also provides a method for controlling its internal contraction ratio. The inlet adjustment control system processes the engine rotor speed signal and the inlet temperature signal, and calculates the command signal adjustment voltage U of the movable throat according to the adjustment law in , and compares it with the movable throat feedback signal U back to form a differential voltage ΔU. After being amplified by a servo amplifier and converted from voltage to current, a driving current is generated to control the electro-hydraulic servo valve to act on the hydraulic cylinder, thereby changing the horizontal position of the movable throat and playing a role in automatically adjusting the internal contraction ratio of the inlet. The structure of this control system is as Figure 4 shown.

[0039] The servo amplifier is mainly composed of electronic components. Its frequency characteristics can be ignored compared with the dynamic characteristics of the inlet duct regulation system. The transfer function can be represented by a proportional link, and the gain is K. s ; The transfer function of the electro-hydraulic servo valve can be approximately regarded as a second-order oscillation link: where K sv is the flow gain of the electro-hydraulic servo valve, ω sv is the natural frequency of the servo valve, and ε sv is the damping ratio of the servo valve; The input signal of the hydraulic cylinder is the output displacement of the electro-hydraulic servo valve, and the output signal is the displacement of the hydraulic cylinder. When only considering the flow characteristics, the transfer function of the hydraulic cylinder is: where K q is the pressure gain of the hydraulic cylinder, ω k is the natural frequency of the hydraulic cylinder, and ε k is the damping ratio of the hydraulic cylinder; The frequency characteristics of the displacement sensor are greater than the frequency response of the inlet duct regulation system, and its transfer function can also be represented by a proportional link, with a gain of K f . The simulation model of the inlet duct regulation system established using Simulink is as Figure 5 shown.

[0040] The working principle of the present invention is as follows: After the supersonic oncoming flow passes through the two-stage compression surfaces on the center cone 1 and the reflected shock wave compression at the lip 2, it enters the contraction section inside the inlet duct. The contraction section inside the inlet duct completes the air flow compression through area contraction. The internal contraction ratio can be controlled by moving the movable throat 3 forward and backward under different oncoming flow conditions. The internal contraction ratio is reduced at low Mach numbers and increased at high Mach numbers. As Figure 1 shown is the turbine mode. At this time, the movable throat 3 is at the most downstream position. After the air flow passes through the internal contraction section, it enters the ramjet channel 4 and the turbine channel 5 respectively. At this time, the air flow entering the turbine channel 5 accounts for the majority, and the ramjet channel 4 bypasses and discharges a part of the air flow; The mode conversion process is as Figure 2 shown. The movable throat 3 moves upstream, thereby closing the turbine channel 5 and guiding the air flow to the ramjet channel 4; In the ramjet mode, the movable throat moves forward as Figure 3 shown. At this time, there is a suction slot in the turbine channel to discharge the boundary layer developed from the center cone 1, and at the same time, the internal contraction ratio of the axisymmetric inlet duct is controlled. When the inlet duct shows a non-starting state, the movable throat 3 can be moved forward to increase the bypass discharge amount and reduce the internal contraction ratio, thereby realizing the starting of the inlet duct. Figure 6 shows the variation laws of the flow coefficient at the outlet of the turbine / ramjet channels and the bypass flow coefficient in the turbine mode from Ma 0 to 3 and in the ramjet mode from Ma 3 to 6. Generally speaking, the flow coefficient at the outlet of the turbine / ramjet channels increases with the increase of the oncoming flow Mach number. In the turbine mode, the bypass discharge amount is about 7.0%, and in the ramjet mode, the bypass discharge amount is less than 5.0%. Figure 7The throat position response curve of the inlet adjustment system established by Simulink is given. It can be seen that the system can respond to a given command within 375 ms and maintain a steady state, indicating that the control signal output according to the above control strategy can effectively control the throat position of the inlet, meet the dynamic characteristic requirements of the inlet throat position adjustment, and has the characteristics of accurate and rapid response.

[0041] The description of the above working principle is only an example of the present invention, which presents the movable throat type series TBCC inlet and its mode conversion scheme proposed by the present invention. Therefore, any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the present invention.

Claims

1. Wide-speed-range integrated series TBCC inlet, characterized in that, The intake duct includes a center cone, a movable throat, a ram channel, and a turbine channel; wherein, both ends of the center cone are pointed and the middle part is thick, the maximum outer diameter of the middle part is located at the lip of the intake duct, half of the center cone is located inside the intake duct, and half is located outside it; the front end of the intake duct is the lip, and behind the lip is the ram channel; inside the intake duct, outside the center cone is the turbine channel, and a movable throat is provided between the turbine channel and the ram channel; The inner diameter of the intake duct is large near the lip position and small at the rear ram channel, and its inner surface matches the outer surface of the movable throat; the maximum outer diameter of the movable throat moves along the axis towards the lip direction until it abuts against the inner wall of the intake duct, and moves in the reverse direction until the inner diameter of the movable throat abuts against the outer diameter of the turbine channel.

2. The wide-speed-range integrated series TBCC inlet according to claim 1, characterized in that, The movable throat is located at the front end of the turbine channel and is sleeved outside the turbine channel for moving along the axis of the center cone outside the center cone.

3. The wide-speed-range integrated series TBCC inlet according to claim 1, characterized in that, The length of the ram channel is less than half of the length of the center cone.

4. The wide-speed-range integrated series TBCC inlet according to claim 1, characterized in that, The outer surface of the movable throat is designed with a spline curve, the outer diameter in the middle is large, and the outer diameters at both ends are small. The middle part of the movable throat is a hollow channel along the axial direction, and the fluid enters the channel and then enters the turbine channel.

5. The method for controlling the internal contraction ratio of the wide-speed-range integrated series TBCC inlet according to claim 1, characterized in that, Collect the engine rotor speed signal and the intake air temperature signal to obtain the command signal regulating voltage for the movable throat , and compare it with the movable throat feedback signal to form a differential voltage . After being amplified by the servo amplifier and converted from voltage to current, a driving current is generated to control the electro-hydraulic servo valve to act on the hydraulic cylinder, thereby changing the horizontal position of the movable throat and adjusting the contraction ratio in the intake passage.

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