CN107091725B - Measuring method for improving accuracy of pressure scanning data of wind tunnel pressure measurement test - Google Patents
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses a measuring method for improving the pressure scanning data precision of a wind tunnel pressure measurement test, which greatly improves the data quality of the wind tunnel pressure measurement test and solves the problem that the surface pressure of a model in a wind tunnel with large fluctuation of a flow field is difficult to carry out high-precision measurement by increasing scanning valve measuring pipelines of total pressure and static pressure signals of the wind tunnel and judging the Mach number according to a scanning valve pressure measurement system.
Description
Technical Field
The invention relates to a wind tunnel test measurement technology, in particular to a measurement method for improving the pressure scanning data precision of a wind tunnel pressure measurement test.
Background
The wind tunnel is a tubular test device which can generate controllable uniform airflow. The wind tunnel model surface pressure distribution measurement test (hereinafter referred to as pressure measurement test) is a wind tunnel test for measuring the pressure distribution on the surface of an aircraft model, unwinding the flow characteristic of the model and providing load data for the structural strength calculation of the aircraft. The conventional pressure distribution test method is to open many pressure measuring holes on the surface of the model, the pressure at the pressure measuring holes is connected to a pressure scanning valve through a connected pipeline, and the pressure data on the surface of the model is obtained through data acquisition and analog-to-digital conversion.
Most of the domestic and foreign wind tunnel pressure distribution measurement tests adopt a step angle-of-attack test mode, namely: in the test process, the wind tunnel control system adjusts the flow field to reach a preset state, controls the attack angle of the model to move to a series of preset positions in sequence, stands still at each preset position for a period of time (hereinafter, the time is referred to as waiting delay wt), so that the pressure in the pressure measuring pipe and the pressure of a measuring point on the surface of the model reach balance, the control system judges that the flow field meets the requirement at the moment, and informs the pressure measuring system of starting to acquire pressure data, otherwise, the control system continues to adjust the flow field until the flow field meets the requirement and informs the pressure measuring system of acquiring the pressure data; the pressure measuring system collects and stores pressure data after receiving the notification and feeds the pressure data back to the control system; and after receiving the feedback, the control system controls the attack angle to continue to move to the next preset position and collects data until the data at all the preset attack angle positions are completely collected, and the test is finished.
When the control system adjusts the state of the flow field, the control system is based on the signals of the total pressure sensor and the static pressure sensor which are arranged in the wind tunnel, the signal has strong real-time performance, and the fluctuation change of the flow field can be reflected quickly. The model surface pressure is measured by connecting an elongated pressure measuring pipeline to a pressure scanning valve, and the pressure change of the pipeline has certain lag relative to the total pressure and the static pressure sensor signal due to the transmission delay (delta t) of the pipeline. And when the control system judges that the flow field is stable at the time t and informs the scanning valve to collect pressure, the pressure collected by the scanning valve is the model surface pressure at the time t-delta t.
When the wind tunnel flow field is relatively stable (Mach number fluctuates slightly within a set range), as long as the set waiting delay wt is long enough (wt is more than delta t), the pressure data which meets the requirement of the flow field is still acquired by the scanning valve, and the pipeline delay cannot cause great influence on the measurement precision. However, when the wind tunnel flow field is not stable (the mach number fluctuation exceeds the set range), although the control system determines that the flow field at the time t meets the requirement, the control system cannot ensure that the time t-delta t also meets the requirement, and therefore, pressure data which are possibly collected by the scanning valve and do not meet the requirement of the flow field can be acquired. In addition, due to the randomness of wind tunnel flow field fluctuation, the repeatability precision of pressure measurement test data acquired for multiple times under the same test condition is poor, and the requirements of model tests are difficult to meet. The problem is prominent in domestic temporary-impulse transonic wind tunnels.
Disclosure of Invention
The invention aims to provide a measuring method for improving the pressure scanning data precision of a wind tunnel pressure measuring test, which is used for solving the problem of poor measurement precision of model surface pressure under the condition of large fluctuation of a flow field in the wind tunnel pressure measuring test.
In order to achieve the purpose, the invention adopts the following technical scheme:
a measuring method for improving accuracy of pressure scanning data of a wind tunnel pressure measurement test comprises the following steps:
the method comprises the following steps: leading out a ventilation pipeline from the wind tunnel total pressure sensor and the static pressure sensor respectively, and connecting the ventilation pipeline to a scanning valve pressure measuring system, wherein the inner diameter and the length of the pipeline are consistent with those of a model pressure measuring pipeline, so that the pipeline has the same pressure transmission delay;
step two: the wind tunnel control system collects total pressure P0 and static pressure Pct measured by a pressure sensor, adjusts a flow field in real time according to Mach number Ma until the flow field meets the requirement, and simultaneously controls the attack angle of the model to reach a preset position;
step three: the wind tunnel control system continuously controls the flow field and keeps the model static for a period of time wt;
step four: the wind tunnel control system calculates the Mach number Ma at the moment, and if the Mach number Ma does not meet the requirement, the flow field is continuously adjusted until the Mach number Ma meets the requirement;
step five: the control system sends an acquisition instruction to the scanning valve pressure measuring system;
step six: the scanning valve pressure measuring system collects the total pressure P0s, the static pressure Pcts and all model measuring point pressures Psi (i = 1-n, n is the number of pressure measuring points on the surface of the model), calculates the Mach number Mas, and stores the data of the group into a buffer area;
step seven: the scanning valve pressure measuring system judges that the Mach number Mas meets the requirement, and then the step eight is carried out;
if the scanning valve pressure measuring system judges that the Mach number Mas does not meet the requirement, the scanning valve pressure measuring system judges whether the repeated collection and judgment times at the current position exceed a threshold value T or not;
and if the Mach number of the data exceeds the threshold value T, the scanning valve pressure measuring system selects a group with the optimal Mach number Mas from the data of the buffer area as the final data of the pressure measuring model at the current position, records the information that the pressure measuring result Mas at the preset position of the current model does not reach the standard, and then executes the step nine.
If the threshold T is not exceeded, the system reverts to step six and continues.
Step eight: the scanning valve pressure measuring system takes the acquired data as final data of the pressure measuring model at the current position and stores the data;
step nine: the scanning valve pressure measuring system empties a buffer zone and sends the information of finishing acquisition to the control system;
step ten: after the control system receives the feedback information, the test is finished.
In the above technical solution, in the sixth step, the buffer area is a storage space, and the size of the storage space is equal to the threshold T multiplied by a storage space required by each group of scan data, and is used for temporarily storing all data groups repeatedly collected at the current position.
In the above technical solution, the acquisition instruction in the fifth step may be a character string with fixed content, or a dynamically generated character string including current test state information, and the scanning valve pressure measurement system may obtain corresponding information by analyzing the character string.
In the above technical solution, the feedback information in the tenth step may be a character string with fixed content, or a dynamically generated character string including the acquisition result information, and the control system may obtain corresponding information by analyzing the character string.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that: according to the measuring method for improving the pressure scanning data precision of the wind tunnel pressure measurement test, the scanning valve measuring pipelines of the total pressure and static pressure signals of the wind tunnel are added, and the Mach number is judged according to the scanning valve system, so that the data quality of the wind tunnel pressure measurement test is greatly improved, and the problem that the surface pressure of a model in the wind tunnel with large fluctuation of a flow field is difficult to measure with high precision is solved.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic connection diagram of a wind tunnel pressure measurement test system;
FIG. 2 is a flow chart of a method of an embodiment.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
According to the specific embodiment of the invention, a measuring method for improving the accuracy of pressure scanning data of a wind tunnel pressure measurement test is disclosed, a connection diagram of a test system adopted by the method is shown in figure 1, and the steps of the measuring method are shown in figure 2.
S201, a total pressure sensor and a static pressure sensor of the wind tunnel are usually respectively arranged in a front chamber and a parking chamber of the wind tunnel body and are not in the same position with the test model. In the wind tunnel test, in order to realize the simultaneous measurement of total static pressure data through the scanning valve, a tee joint is needed to be used for branching a pressure pipeline of the sensor and connecting the pressure pipeline to a pressure measuring system of the pressure scanning valve.
The pressure measuring pipeline in this embodiment generally adopts a plastic hose with an inner diameter of 0.8mm to 1.0mm, and since the pipeline is thin, the pressure change on the surface of the model is transmitted to the pressure measuring port of the pressure scanning valve with a certain transmission delay (delta t), and in order to keep the synchronism of signals such as total static pressure signals measured by the scanning valve, wind tunnel flow field fluctuation, model surface pressure and the like, hoses with the same length and inner diameter specification can be used for connecting the model pressure measuring point of the scanning valve and the total static pressure sensor. If the specifications of the used pipelines are different, the proper length or inner diameter needs to be selected through experimental tests or theoretical analysis and calculation.
S202, the wind tunnel control system collects measured values P0 and Pct of the total static pressure sensor in real time according to a control period, calculates Mach number Ma, continuously adjusts a flow field according to test requirements, enables Ma to be stable in a certain range, and simultaneously controls the attack angle of the model to reach a preset position.
The preset attack angle position is usually a sequence of attack angles of the model, such as "-2, 0,2,4, 6", the wind tunnel control system firstly moves the model to-2 degrees, then collects data, then moves to 0 degree, then collects data, and so on, and the test is finished when the data collection of the model at 6 degrees is finished.
S203, after the attack angle of the model reaches the preset position, the wind tunnel control system continuously controls the flow field and keeps the model static for a period of time wt.
The waiting time wt is a fixed value set before the test, and the value of the waiting time wt is larger than the transmission delay delta t of the pressure measuring pipeline.
And S204, after the time delay is carried out, in order to ensure that the flow field still meets the requirement, the wind tunnel control system needs to calculate the Mach number Ma again, and if the flow field does not meet the requirement, the flow field is continuously adjusted until the flow field meets the requirement.
S205, the control system sends an acquisition instruction to the scanning valve pressure measuring system. The instruction may be a character string with fixed content or a dynamically generated character string containing current test state information, and the scanning valve pressure measurement system may obtain corresponding information by analyzing the character string.
S206, after receiving the acquisition instruction, the scanning valve pressure measurement system acquires the accessed total pressure P0s, static pressure Pcts and all model measuring point pressures Psi (i = 1-n, n is the number of pressure measuring points on the surface of the model), calculates the Mach number Mas, and stores the data of the group into a buffer area.
The buffer is a storage space, and the size of the storage space is equal to the threshold T in S209 multiplied by the storage space required by each group of scan data, so as to temporarily store all data groups repeatedly acquired at the current position.
And S207, judging whether the Mach number Mas meets the requirement by a scanning valve pressure measuring system. If the requirement is met, the pressure data meeting the requirement is obtained, and the step S208 is carried out; if the requirement is not met, the process goes to step S209 for further determination.
And S208, the scanning valve pressure measuring system takes the acquired data as final data of the pressure measuring model at the current position and stores the data, and then the step S211 is executed.
S209, the scanning valve pressure measuring system judges whether the repeated collection times at the current model preset position exceed a threshold value T, if so, the step S210 is carried out, and if not, the step S206 is carried out to continue collection and judgment.
The threshold value T is an integer value preset by a scanning valve pressure measuring system, and the integer value limits the maximum times of repeatedly trying to acquire pressure data under each model attack angle position. When the flow field is very unstable, the Mas calculated by the scanning valve pressure measuring system may not meet the requirement, so that the wind tunnel control system waits for the feedback of the scanning valve pressure measuring system for a long time, which causes energy waste.
S210, the step shows that the number of times of attempted acquisition of the model at the current preset position exceeds a threshold value T, data which meets the Mas requirement are not obtained, in order to save energy, the scanning valve pressure measuring system selects a group of data with the optimal Mas from the buffer area at the moment as a pressure measuring result of the current model preset position and stores the pressure measuring result, and then S211 is executed.
Furthermore, warning information that the pressure measurement result Mas of the current model preset position does not reach the standard can be recorded in a test log, so that problems can be conveniently checked.
S211, the scanning valve pressure measuring system empties a buffer zone and sends the collected feedback information to the control system.
The feedback information may be a character string with fixed content or a character string which contains acquisition result information and is generated dynamically, and the control system may obtain corresponding information by analyzing the character string.
Further, before the scanning valve pressure measuring system empties the buffer zone, the data of the buffer zone can be saved to a file for analyzing the test process.
S212, after the control system receives the feedback information, if other preset model positions exist, the control system goes to S202 to repeat the processing, and if not, the test is finished.
The mach numbers Ma and Mas in step S202 and step S206 are calculated from total static pressure data and the formula (1).
It should be noted that the "sensor", "pressure measuring hole", "pressure measuring line" or "pressure scanning valve" in the specification and claims of the present invention and the drawings may be single or plural in number. The control system sends a collection instruction and a collection completion instruction fed back by the scanning valve pressure measuring system to the scanning valve pressure measuring system, wherein the collection completion instruction can be a fixed character string or a dynamically generated character string containing current test state information, and a receiving party can obtain corresponding information by analyzing the character string. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion, such that a process that includes a sequence of steps is not necessarily limited to those steps explicitly listed, but may include other steps not explicitly listed that are inherent to such steps, such as a step of saving data inherently including steps of opening and closing a file, etc.
According to the measuring method for improving the accuracy of the pressure scanning data of the wind tunnel pressure measurement test, provided by the specific embodiment of the invention, the scanning valve measuring pipelines of the total pressure and static pressure signals of the wind tunnel are added, and the Mach number judgment is carried out according to the scanning valve system, so that the data quality of the wind tunnel pressure measurement test is greatly improved, and the problem that the surface pressure of a model in the wind tunnel with large fluctuation of a flow field is difficult to carry out high-accuracy measurement is solved.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.
Claims (4)
1. A measuring method for improving accuracy of pressure scanning data of a wind tunnel pressure measurement test is characterized by comprising the following steps:
the method comprises the following steps: the total pressure sensor and the static pressure sensor of the wind tunnel are respectively arranged in a front chamber and a parking chamber of the wind tunnel body and are in different positions from the test model, a vent pipeline is respectively led out from the total pressure sensor and the static pressure sensor of the wind tunnel by utilizing a three-way joint and is connected into a scanning valve pressure measuring system, and the inner diameter and the length of the vent pipeline are consistent with those of the pressure measuring pipeline of the model, so that the vent pipeline has the same pressure transmission delay;
step two: the wind tunnel control system collects total pressure P0 and static pressure Pct measured by a pressure sensor, adjusts a flow field in real time according to Mach number Ma until the flow field meets the requirement, and simultaneously controls the attack angle of the model to reach a preset position;
step three: the wind tunnel control system continuously controls the flow field and keeps the model static for a period of time wt;
step four: the wind tunnel control system calculates the Mach number Ma at the moment, and if the Mach number Ma does not meet the requirement, the flow field is continuously adjusted until the Mach number Ma meets the requirement;
step five: the control system sends an acquisition instruction to the scanning valve pressure measuring system;
step six: the scanning valve pressure measuring system collects the total pressure P0s, the static pressure Pcts and all model measuring point pressures Psi, wherein: i is 1-n, n is the number of pressure measuring points on the surface of the model, the Mach number Mas is calculated, and the data of the group are stored in a buffer area;
step seven: the scanning valve pressure measuring system judges that the Mach number Mas meets the requirement, and then the step eight is carried out;
if the scanning valve pressure measuring system judges that the Mach number Mas does not meet the requirement, the scanning valve pressure measuring system judges whether the repeated collection and judgment times at the current position exceed a threshold value T or not;
if the Mach number exceeds the threshold value T, the scanning valve pressure measuring system selects a group with the optimal Mach number Mas from the data of the buffer area as the final data of the pressure measuring model at the current position, and records the information that the pressure measuring result Mas at the preset position of the current model does not reach the standard; then, the step nine is executed;
if the threshold T is not exceeded, the system goes to the step six again to continue the execution;
step eight: the scanning valve pressure measuring system takes the acquired data as final data of the pressure measuring model at the current position and stores the data;
step nine: the scanning valve pressure measuring system empties a buffer zone and sends the information of finishing acquisition to the control system;
step ten: after the control system receives the feedback information, the test is finished.
2. The measurement method for improving accuracy of pressure scan data in wind tunnel manometry tests according to claim 1, wherein in step six, the buffer area is a storage space, and the size of the storage space is equal to the threshold value T multiplied by the storage space required by each set of scan data, and is used for temporarily storing all data sets repeatedly collected at the current model position.
3. The method according to claim 1, wherein the acquisition instruction in the fifth step is a character string with fixed content or a dynamically generated character string containing current test state information, and the scan valve pressure measurement system can obtain corresponding information by analyzing the character string.
4. The method according to claim 1, wherein the feedback information in the step ten is a character string with fixed content or a dynamically generated character string containing information of the acquired result, and the control system can obtain corresponding information by analyzing the character string.
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| CN112881004A (en) * | 2021-01-11 | 2021-06-01 | 中国空气动力研究与发展中心高速空气动力研究所 | Airspeed tube wind tunnel check test device and check test method |
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