Temporary flushing type wind tunnel system adopting reverse brayton cycle to control temperature and test method
Technical Field
The invention belongs to the technical field of wind tunnel tests, and particularly relates to a temporary flushing wind tunnel system adopting an inverse brayton cycle to control temperature and a test method.
Background
Transonic flight and flow processes have many viscous dominant complex flow phenomena, such as boundary layer development and transition, flow separation, shock wave and boundary layer interference, and the like, which directly affect aerodynamic characteristics of aircraft and turbomachine blades. In order to adapt to the development and development of advanced aircrafts and turbomachinery, the Reynolds number simulation capability of a transonic wind tunnel needs to be improved, and a high Reynolds number wind tunnel system needs to be designed and a blowing test method needs to be established.
The reverse brayton cycle comprises 4 processes of isentropic compression, isobaric cooling, isentropic expansion and isobaric heat absorption, and the processes respectively comprise a compressor, a heat exchanger, a turbo expander and cooling equipment, wherein the efficient turbo expander is a key equipment for determining the energy efficiency of the reverse brayton cycle. The reverse brayton thermodynamic cycle has the advantages of simple system, reliable operation, wide temperature range, easy availability of working medium (air can be used as a circulating medium), and the like, and is particularly widely applied and developed in the fields of refrigeration and low temperature.
For the wind tunnel, through reasonable thermodynamic design of the inverse brayton cycle, the gas working medium can be guaranteed to have higher operation efficiency at a design point after nearly isentropic adiabatic expansion by the turbine expander, the gas working medium can be expanded deeply, a saturated or gas-liquid two-phase state is achieved at an outlet of the turbine expander, more sufficient heat exchange cold energy is provided for the wind tunnel, and the wind tunnel is an effective means for further improving the experimental simulation Reynolds number. Therefore, through a certain control means, the reverse brayton cycle of the turbine expander can enable the wind tunnel to work in a wide temperature range from normal temperature to low temperature, the elasticity and the temperature control precision of the wind tunnel test working condition are obviously improved, and the economy and the persistence of wind tunnel production are improved.
Currently, there is a need to develop a temporary impact wind tunnel system and test method that uses the inverse brayton cycle to control temperature.
Disclosure of Invention
The invention aims to solve the technical problem of providing a temporary flushing type wind tunnel system adopting inverse brayton cycle to control temperature, and the technical problem of the invention is to provide a temporary flushing type wind tunnel test method adopting inverse brayton cycle to control temperature.
The invention relates to a temporary flushing wind tunnel system adopting inverse brayton cycle to control temperature, which is characterized by comprising a raw material air source, a raw material air purifying device, a compressor cooler, a high-temperature side of a heat regenerator, a turbine expander and a heat exchange device in a wind tunnel body, wherein the raw material air source, the raw material air purifying device, the compressor cooler, the high-temperature side of the heat regenerator, the low-temperature side of the heat regenerator and a low-temperature side outlet of the heat regenerator are sequentially connected along the air flow direction and are directly connected with the atmosphere or connected with the raw material air source; the wind tunnel body is also provided with a tunnel body air source outside, and the tunnel body air source supplies air to the wind tunnel body along the air flow direction of the wind tunnel body; the heat-insulating layer covers equipment, pipelines and valves with the air flow temperature lower than or higher than the ambient temperature in the wind tunnel system;
the heat exchange device is one of a heat exchanger and an air flow input/discharge device; when the heat exchanger is selected, the gas used by the turbine expander is the same as or different from the gas of the wind tunnel body; when the air flow input/output device is selected, the gas used by the turbine expander is the same as the gas of the wind tunnel body.
Further, the compressor is a one-stage or multi-stage compressor, and the compressor cooler is a one-stage or multi-stage compressor cooler matched with the compressor.
Further, the heat regenerator is a one-stage or multi-stage heat regenerator.
Further, the turbo expander is a one-stage or multi-stage turbo expander.
Further, the thermal state of the outlet air flow of the turbine expander is single-phase superheated fluid or gas-liquid two-phase fluid.
Further, the wind tunnel test section in the wind tunnel body is a straight-through section or a molded surface structure section.
Further, the heat exchanger is arranged at any section in the wind tunnel body.
Further, the inlet and the outlet of the air flow input/output device are arranged at the same section of the wind tunnel body or are arranged at two different sections of the wind tunnel body separately.
The invention discloses a temporary flushing wind tunnel test method adopting inverse brayton cycle to control temperature, which comprises the following steps:
a. purifying gas; the raw material gas in the raw material gas source enters a raw material gas purification device, pure gas working medium in the raw material gas is reserved, and alkanes, carbon dioxide, water and impurities are removed to obtain gas I;
b. compressing and cooling the gas; the gas I is compressed by a compressor, the pressure and the temperature are increased, and then the gas I is cooled by a compressor cooler and cooled to the ambient temperature to obtain gas II;
c. expanding the gas; the gas II passes through the high temperature side of the heat regenerator, the temperature is continuously reduced in the heat regenerator to obtain gas III, the gas III enters a turbine expander to perform isentropic expansion and cooling, and in the turbine expander, the gas III performs superheated single-phase expansion or two-phase expansion according to the wind tunnel test requirement to obtain gas IV;
d. blowing in a wind tunnel; the gas IV enters the wind tunnel body, exchanges heat with a heat exchange device in the wind tunnel body and then enters a test section to provide blowing air flow meeting the requirements of Reynolds number and Mach number of wind tunnel test, wind tunnel test is carried out, and the outlet air flow is gas V;
e. treating residual gas; the gas V enters the low-temperature side of the heat regenerator, exchanges heat with the gas II in the heat regenerator, and is subjected to rewarming to obtain a gas VI, and the gas VI is directly discharged to the atmosphere from an outlet of the low-temperature side of the heat regenerator or enters a raw material gas purification device for recycling.
The raw material gas in the raw material gas source of the temporary flushing wind tunnel system adopting the inverse Brayton cycle to control the temperature is purified, compressed and cooled by a raw material gas purifying device, a compressor and a compressor cooler; then heat exchange and cooling are carried out through a heat regenerator, and adiabatic expansion is carried out through a turbine expander; the outlet air flow of the turbine expander is conveyed to a test section in the wind tunnel body for temperature control of test air flow, the air flow out of the wind tunnel body is exhausted, or the air flow returns to the heat regenerator for exhausting, and the air flow can also circularly enter the raw material gas purifying device for recompression. The hole body air source supplements test air flow for the temporary flushing wind tunnel. Aiming at the low-temperature working condition, heat preservation measures are adopted for equipment, pipelines and valves needing heat preservation. When the outlet airflow of the turbine expander enters the wind tunnel body, two temperature control modes exist: firstly, non-contact dividing wall type heat exchange is carried out on the air flow in the hole body through the heat exchanger, and secondly, the air flow is directly mixed with the air flow in the hole body through the air flow input/discharge device and is discharged.
The invention adopts the compressor, the regenerator, the turbine expander and the wind tunnel body in the temporary flushing wind tunnel system of the reverse brayton cycle control temperature to form four main parts of the reverse brayton cycle, which sequentially play roles as follows: the compressor is used for pressurizing the raw material gas or the circulating gas of the raw material gas, the regenerator is a heat exchange component of compressed air flow and reflux air flow, the turbine expander is used for providing cooling cold energy, the wind tunnel body is used as cooling equipment, and the reverse brayton system is formed together for controlling and adjusting the temperature of the test air flow of the test section.
The temporary flushing wind tunnel test method adopting the reverse brayton cycle to control the temperature is characterized in that the temperature of test air flow of a test section is adjusted by controlling the expansion working state of a turbine expander and conveying the outlet air flow of the turbine expander into a wind tunnel; the total temperature adjusting range of the test air flow of the test section is wide, and the static temperature of the wind tunnel test section can be deep into a low temperature region from normal temperature, so that the Reynolds number and Mach number simulated by the wind tunnel test are expanded; removing raw gas impurities except the gas working medium of the test section by using a purification system; the temperature of the test air flow of the test section is regulated by using the mode of cooling and self-regenerative cycle of the turbine expander, the total temperature of the test air flow can be regulated rapidly and accurately according to actual use requirements, and meanwhile, a gas working medium different from the test air flow can be adopted in the reverse brayton cycle, so that the air blowing temperature of the test section is reduced rapidly, and meanwhile, the energy efficiency and the economical efficiency of a wind tunnel system are improved effectively.
The temporary flushing wind tunnel system adopting the inverse brayton cycle to control the temperature has the advantages of simple structure, simple flow of the wind tunnel test method, wide temperature adjustable range, high temperature control precision, multiple types of selectable gas working media, high operation elasticity, low unit energy consumption and high potential for improving the simulation Reynolds number.
Drawings
FIG. 1 is a schematic diagram of a temporary flushing wind tunnel system embodiment employing a heat exchanger;
FIG. 2 is a schematic diagram of a temporary impact wind tunnel system using an air flow input/output mode according to an embodiment of the present invention.
In the figure, a raw material gas source 2, a raw material gas purifying device 3, a compressor 4, a compressor cooler 5, a heat regenerator 6, a turbine expander 7, a wind tunnel body 8, a tunnel body gas source 9, a heat insulating layer 10, a heat exchanger 11 and a gas flow input/discharge device.
Detailed Description
In order to make the technical problems, technical solutions and advantages to be solved more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.
The temporary flushing wind tunnel system adopting the reverse brayton cycle to control the temperature comprises a raw material gas source 1, a raw material gas purifying device 2, a compressor 3, a compressor cooler 4, a high-temperature side of a heat regenerator 5, a turbine expander 6 and a heat exchange device in a wind tunnel body 7 which are sequentially connected along the direction of the gas flow, wherein the low-temperature side of the heat regenerator 5 and an outlet of the low-temperature side of the heat regenerator 5 are directly connected with the atmosphere or connected with the raw material gas source 1; the air tunnel body 7 is also provided with a tunnel body air source 8, and the air tunnel body air source 8 supplies air into the air tunnel body 7 along the air flow direction of the air tunnel body 7; the heat preservation layer 9 covers equipment, pipelines and valves with the air flow temperature lower than or higher than the ambient temperature in the wind tunnel system;
the heat exchange device is one of a heat exchanger 10 or an air flow input/output device 11; when the heat exchanger 10 is selected, the gas used by the turbine expander 6 is the same as or different from the gas of the wind tunnel body 7; when the air flow inlet/outlet device 11 is selected, the gas used by the turbo expander 6 is the same as the gas used by the wind tunnel body 7.
Further, the compressor 3 is one-stage or multi-stage compressor 3, and the compressor cooler 4 is one-stage or multi-stage compressor cooler 4 matched with the compressor 3.
Further, the regenerator 5 is one-stage or multi-stage regenerator 5.
Further, the turbo expander 6 is a one-stage or multi-stage turbo expander 6.
Further, the thermal state of the outlet air flow of the turbine expander 6 is single-phase superheated fluid or gas-liquid two-phase fluid.
Further, the wind tunnel test section in the wind tunnel body 7 is a straight-through section or a profile structure section.
Further, the heat exchanger 10 is arranged at any section in the wind tunnel body 7.
Further, the inlet and the outlet of the air flow inlet/outlet device 11 are provided at the same section of the wind tunnel body 7 or at two different sections of the wind tunnel body 7 separately.
The invention discloses a temporary flushing wind tunnel test method adopting inverse brayton cycle to control temperature, which comprises the following steps:
a. purifying gas; the raw material gas in the raw material gas source 1 enters a raw material gas purification device 2, pure gas working media in the raw material gas are reserved, and alkanes, carbon dioxide, water and impurities are removed to obtain gas I;
b. compressing and cooling the gas; the gas I is compressed by a compressor 3, the pressure and the temperature are increased, and then the gas I is cooled by a compressor cooler 4 and cooled to the ambient temperature to obtain a gas II;
c. expanding the gas; the gas II passes through the high temperature side of the heat regenerator 5, the temperature is continuously reduced in the heat regenerator 5 to obtain gas III, the gas III enters the turbine expander 6 to be subjected to isentropic expansion and cooling, and the gas III is subjected to superheated single-phase expansion or two-phase expansion in the turbine expander 6 according to the wind tunnel test requirement to obtain gas IV;
d. blowing in a wind tunnel; the gas IV enters the wind tunnel body 7, exchanges heat with a heat exchange device in the wind tunnel body 7 and then enters a test section to provide blowing air flow meeting requirements of Reynolds number and Mach number of wind tunnel test, wind tunnel test is carried out, and the outlet air flow is gas V;
e. treating residual gas; the gas V enters the low-temperature side of the heat regenerator 5, exchanges heat with the gas II in the heat regenerator 5, and is subjected to rewarming to obtain a gas VI, and the gas VI is directly discharged to the atmosphere from an outlet of the low-temperature side of the heat regenerator 5 or enters the raw material gas purification device 2 for recycling.
Example 1
In the embodiment, as shown in fig. 1, the key position is that the gas iv enters a heat exchanger 10 in a wind tunnel body 7, the dividing wall type heat exchange is carried out on the gas flow in the wind tunnel body 7, the blowing gas flow meeting the requirements of the Reynolds number and Mach number of the wind tunnel test is provided, the wind tunnel test is carried out, and the gas flow at the outlet of the heat exchanger 10 is the gas v;
example 2
The main difference between this embodiment and embodiment 1 is that, as shown in fig. 2, the gas iv enters the gas flow input/output device 11 in the wind tunnel body 7, and is mixed with the gas flow of the wind tunnel to perform heat exchange, so as to provide the blowing gas flow meeting the reynolds number and mach number requirements of the wind tunnel test, and perform the wind tunnel test, and the outlet gas flow of the gas flow input/output device 11 is the gas v.
It is noted that the inlet of the air flow inlet/outlet means 11 is in the present position of fig. 2, but the outlet may be arranged at any position downstream of the stabilizing section of the tunnel body 7.
In the embodiment 1 and the embodiment 2, a temperature regulation method of a wind tunnel system based on the reverse brayton cycle of a turbine expander is adopted, namely compressed gas enters a wind tunnel body 7 to regulate the temperature of test air flow of a test section after isentropic adiabatic expansion, temperature reduction and depressurization of the turbine expander 6, the total temperature state of the test air flow required by wind tunnel test is provided, so that the Reynolds number and Mach number indexes required by the test section are met, particularly, the necessary cold energy for low-temperature operation is provided, and the Reynolds number is increased through temperature reduction. The expansion ratio and the rotation speed of the turbine expander 6 can be changed or adjusted at will within the range that the turbine technical conditions can be achieved, the turbine expander 6 can be matched with the total temperature requirement of the test air flow of the test section according to the wind tunnel test requirement, isentropic adiabatic expansion is further carried out to a gas-liquid two-phase state, the gas-liquid two-phase air flow which is close to or reaches the same pressure is provided, and the simulated Reynolds number and Mach number of the wind tunnel test are further improved. Under the condition that the gas working medium is nitrogen, the temperature of the low Wen Wenou can be reduced to liquid nitrogen, the turbine expander 6 can stably operate from a normal temperature region to a low temperature region, and the wind tunnel high-simulation Reynolds number test can be performed after the turbine expander goes deep into the low temperature region.
The specific embodiments of examples 1 and 2 are as follows:
purifying the gas in the raw material gas source 1 by a raw material gas purifying device 2 to remove impurities and obtain gas I; and then passes through a compressor 3 and a compressor cooler 4 for compression and cooling to obtain gas II, wherein the compression-cooling process can use a multistage compressor 3 and the compressor cooler 4 to be arranged in series so as to achieve the gas pressure required by the temporary flushing wind tunnel system. And then conveying the purified, compressed and cooled gas II to the regenerators 5 for preliminary heat exchange and cooling to obtain gas III, wherein a plurality of regenerators 5 can be arranged in series in the heat exchange process so as to achieve the required turbine inlet air flow temperature. The gas III after heat recovery enters a turbine expander 6 to carry out adiabatic expansion to obtain gas IV, and the adiabatic expansion process can also carry out multistage turbine expander 6 series arrangement according to the requirement; the heat-insulating expanded gas IV is conveyed to the wind tunnel body 7 to regulate the temperature of the test air flow of the test section, the mode that the gas IV regulates the temperature of the test air flow of the test section can be adopted, a heat exchanger 10 is arranged in the wind tunnel body 7, or the mode that the gas IV is directly conveyed into the wind tunnel body 7 to be mixed with the air flow of the wind tunnel body and discharged can be adopted, the outlet air flow of the heat exchanger 10 or the air flow input/discharge device 11 is gas V, and the gas V can be exhausted or subjected to heat exchange with the gas II through the heat regenerator 5 to obtain gas VI; the gas VI can be vented or recycled into the feed gas source 1 for recompression.
Wherein gas ii can be cooled to ambient temperature and provides the desired inlet pressure value for the turboexpander 6. The gas pressure of the gas III is determined according to the required inlet pressure of the turbine expander 6 and the total pressure of the air flow in the wind tunnel test section, and superheated single-phase expansion or gas-liquid two-phase expansion is carried out in the turbine expander 6 according to the working condition of the wind tunnel test. Gas IV provides the total temperature conditions of the wind tunnel test required by the test section. The gas V is directly discharged to the atmosphere, or the gas V enters the gas inlet II of the heat regenerator 5 to exchange heat with the gas II in the heat regenerator 5, and the gas VI is obtained after the heat recovery and is directly discharged to the atmosphere from the gas outlet II of the heat regenerator 5 or enters the raw material gas purifying device 2 to be recycled.
The hole body air source 8 supplements test air flow for the temporary flushing wind tunnel.
The insulation 9 is provided on equipment, pipes and valves where the temperature of the gas stream in the cycle is lower or higher than the ambient temperature, as required.
When the wind tunnel adopts the heat exchanger 10 to perform dividing wall type heat exchange, the heat exchanger 10 can be reasonably arranged at any section of the wind tunnel body 7.
When the wind tunnel adopts the airflow input/output device 11 to perform direct mixing heat exchange, the input port and the output port of the airflow input/output device 11 can be separately arranged at two different sections of the wind tunnel body 7.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.