JPH0585860B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for measuring the hydrodynamic characteristics of a suspended wind cylinder model, more specifically, a method for measuring the hydrodynamic characteristics of a suspended wind cylinder model, and more specifically, a method for measuring the hydrodynamic characteristics of a wind cylinder model suspended in the wind cylinder using wire rods, etc. The present invention relates to a method for measuring the hydrodynamic properties of a wind cylinder model, which is used to experimentally measure the forces and/or moments applied to the model under various airflows.

[Conventional technology]

When developing airplanes, spaceflight objects, buildings, architectural structures such as bridges, automobiles, orbital vehicles, etc., a small model is prepared in advance before the actual product is manufactured, and this model is installed inside the wind cylinder and used for various purposes. The hydrodynamic properties of the model are being tested under various airflow conditions expected for the attitude of the model. Such measurements can avoid various risks associated with actual experiments, and can quickly and inexpensively confirm trends in fluid dynamic characteristics.
Therefore, wind cylinder tests using a wind cylinder model are always used in the early stages of development.

There are two main methods for measuring the hydrodynamic characteristics of a suspended wind cylinder model. That is, there are two methods: a measurement method using a model suspended from a plurality of thin wire rods, and a measurement method using a model fixed to a string or the like. In the former support method, the force and moment applied to the model are measured by measuring the weight transmitted to the catenary wire of the model. In the latter support method, forces and moments are directly measured using a multi-force detector mounted inside the model along with a holding member. Which support method should be adopted for test measurements of the wind cylinder model?
It is determined by the purpose, external conditions, etc. The former support method is advantageous when the model has a wide variety of postures, although the relative speed of the airflow to the model is relatively slow. On the other hand, the latter support method is advantageous when limiting the posture of the model to a certain specific situation and measuring the hydrodynamic characteristics with high precision especially when exposed to strong air currents.

The present invention is concerned with improving a method of measuring the hydrodynamic characteristics of a wind cylinder model by adopting the former support method. In order to clarify the differences between the model suspension support system of the present invention and the conventional support system, the conventional support system will be briefly summarized here.

Figure 4 shows the six components of force exerted by the test airflow on the wind body model (in this case, it is a model of an airplane for simplicity), that is, the resistance force (the opposite is the thrust force), the lateral force,
The three types of forces that are lift forces (hereinafter, F _X , F _Y , respectively)
three types _of moments (hereinafter referred to as _M
A traditional support method according to the prior art for measuring M _Y , _Z ) is shown. As shown in the figure, in the horizontal type, wire rods are hung from six support positions F ₁ to _{F 6} installed above, and among these, support positions F ₄ , F ₅ , and
The three suspension points 2, 1, and 3 of the airplane are connected to the tips of three wire rods suspended from F ₆ , respectively, and the same wire rods are connected vertically to the suspension points 2 and 1 with weights.
Hang W ₃ and W ₄ . Furthermore, a thin wire is pulled out parallel to the X axis (that is, horizontally) from the suspension points 2 and 1,
A fulcrum C ₁ vertically lowered from the support positions F ₁ and F ₂ ,
The wire pulled out horizontally via C ₂ is guided diagonally downward by 45 degrees and fixed at fixing points G ₁ and G ₂ . In that case, in order to maintain the balance of force against the horizontal wire, the wire goes down vertically from the support position _F6 , and from the suspension point 3, the end of the wire comes out diagonally 45 degrees downward in the X-axis direction and passes through the pulley _Q1. Hang a weight W ₁ on the. A similar equilibrium is Y
Also applies in the axial direction. That is, suspension point 2 of the airplane
The wire pulled out horizontally in the Y-axis direction from the fulcrum C ₃
Pull it diagonally downward by 45 degrees in the Y-axis direction and fix it at the fixing point _G3.
Stop at. In that case, connect the wire vertically from the support position F ₃ to the fulcrum C ₃ . Also, from suspension point 1 to Y
Pull out the wire horizontally to the shaft, and maintain balance in the Y-axis direction with a weight _W2 suspended via a pulley _Q2 . Airflow blows parallel to the X-axis, so when changing the airplane _'s attitude, it _is necessary to
G ₁ to G ₃ are installed on the same frame.
In that case, the support positions F ₁ to _{F 6} are fixed to the frame via a balance that measures the weight in the vertical direction.

In this arrangement, the normal forces acting on the suspension points 2, 1, 3 are measured by balances placed at support positions F ₄ , F ₅ , F ₆ respectively. The horizontal force in the X-axis direction acting on the suspension points 2 and 1 is applied by the balances installed at the support positions F ₁ and F ₂ , respectively, and the force acting in the Y direction is applied to the support position F ₁
It is measured by a balance installed at

As can be easily imagined from the arrangement shown in FIG. 4, this model support method has various drawbacks, and there are limits to measurement conditions and measurement accuracy. These difficulties can be summarized as follows.

(1) It takes an extremely long time to balance the support wire in the horizontal and vertical directions with respect to the suspension point, and if the support at one point is incomplete, the effect will spread to other support points, and the overall It is often necessary to redo the support. Therefore, installing a wind fuselage model requires experience and skill.

(2) In the end, when setting up the model mentioned above, it is necessary to endure a certain degree of imperfect balance.
In order to calibrate measurement errors based on this, it is necessary to create a program in advance to correct the final data synthesized from the outputs of the six-component force detector each time the support arrangement is completed.

(3) The mount for the support frame becomes very large. This is because the support positions F ₁ to _{F 6} and their balances are supported on the ceiling, and the fixing points G ₁ to _{G 3} are provided at the bottom.
Moreover, pulleys Q ₂ and Q ₁ for weights W ₁ and W ₂ are installed on the side.
This is because it is necessary to provide In other words, this model support method requires a large space both vertically and horizontally, and requires the preparation of large wind tunnel equipment.

(4) To conduct wind barrel tests for various flight positions, it is necessary to rotate the airplane around its X, Y, and Z axes. In that case, the support position F ₁ ~
It is necessary to move F ₆ , the fixed points G ₁ and G ₂ , and the pulleys Q ₂ and Q ₁ at the same time, and the moving mechanism provided for the frame becomes large-scale.

(5) The range of posture variation is extremely low. This is because in Figure 4, for example, when rotating around the Z axis, the fulcrum
This is because C ₁ or C ₂ covers the front of the airplane and disrupts the airflow, making measurement impossible. Of course, even if the airflow hits right next to the airplane, the fulcrum C ₃ or the pulley Q ₂ or Q ₁ will cause turbulence in the airflow, making measurement impossible.

The disadvantages of the traditional suspension support systems according to the prior art, as exemplified above, are of course also found in models of other structures other than airplanes. Further, although the explanation has been given in the case of six-component force measurement, the same tendency is encountered even when the force components to be resolved are less than six-component forces.

In particular, recent advances in technology have expanded the measurement conditions and range of measurements in wind cylinder tests, requiring increasingly high precision and constant reproducibility. However, satisfactory developments have not yet been proposed in a suspension system for a wind cylinder model that meets this demand, and in a corresponding method for measuring hydrodynamic characteristics.

[Problem that the invention seeks to solve]

In view of the various drawbacks found in the conventional suspension system for wind cylinder models mentioned above, an object of the present invention is to facilitate the initial adjustment and preliminary calibration operations, provide excellent measurement accuracy and reproducibility, and provide a suspension support mount. To provide a method for measuring the hydrodynamic characteristics of a suspended wind cylinder model, which allows the wind cylinder equipment and attitude control mechanism to be miniaturized, and the attitude range of the wind cylinder model to be largely variable. It is in.

[Means for solving problems]

The above problem can be solved by the present invention, in which three pairs of fixed points are provided on the frame of the mount in the wind cylinder, one multi-force detector is fixed to each fixed point, and one multi-force detector is fixed to each fixed point. Using connected wires,
The three suspension points of the wind cylinder model, which are arranged corresponding to the three sets of fixed points, are suspended, and the wind cylinder model is adjusted to the desired position so that the wire rods are under tension in the calm wind and test airflow due to the weight of the model. The orthogonal three-component forces and/or moments acting on the origin of the wind cylinder model are calculated from the measured force components detected by each detector while suspended and supported in a windless state. Calculate the orthogonal three component forces and/or moments acting on the origin of the wind cylinder model from the detected measured force components, and calculate both forces and/or moments.
Alternatively, the problem has been solved by a method for measuring the hydrodynamic characteristics of a suspended wind model, which is characterized by calculating the effective force and/or moment acting on the model from the moment.

Further advantageous embodiments are described in the claims 2-4.

[Effect]

In the method for supporting a wind cylinder model according to the present invention, the model is statically supported at three suspension points, and each suspension point is supported by a wire rod extending from a pair of detectors capable of measuring trigonometric components of force. The hydrodynamic characteristic amount acting on this wind barrel model derives the force measured by the detector according to a predetermined arithmetic formula. In addition, the 6-component force acting on the wind cylinder model was calculated from the above calculated values in the test state with no wind and with wind.

〔Example〕

The present invention will be explained in more detail below based on the drawings showing preferred embodiments.

FIG. 1A shows a perspective view of the arrangement for measuring the hydrodynamic characteristics of the wind cylinder model A according to the present invention.

Here, too, the wind fuselage model A is illustrated as an airplane. The three different points 1, 2, and 3 of the wind cylinder model A are fixedly connected to three pairs of fixed points 11, 12, 21, 22, 31, and 32 of the mount frame (not shown), respectively. Two pairs each made of piano wire or a reinforced synthetic resin such as Kevlar are attached from three-component force detectors (not shown; henceforth each of these fixed points will be accompanied by one component-force detector). This model A is held in a predetermined position by suspension wires (reference numerals are omitted to avoid complicating the drawing). In that case, the six wires will not slacken,
In addition, the weight of the model is adjusted so that all the suspension wires are taut and do not loosen, for example, do not fly up, regardless of the wind speed and/or wind direction within the measurement range.

If the weight of the model itself is insufficient due to the weight adjustment described above, the weight may be adjusted to a desired value by fixing an auxiliary weight within the model or by appropriately selecting the model material and, for example, the wall thickness. If this procedure still results in insufficient weight, one or more additional weights may be suspended from wire rods at the bottom of the model. 6 fixed points 1
1, 12, 21, 22, 31, and 32 do not necessarily need to be installed in the same plane.

The multi-force detector described above does not need to be able to measure moment components, but one that can measure three orthogonal force components is used. Furthermore, the measurement tolerance range of these multi-force detectors needs to accommodate gravity during rest and testing in the vertical direction (corresponding to the Z-axis direction in the case of FIG. 1A).

Fig. 1B shows the geometrical arrangement of each multi-force detector and the wind cylinder model A, which is the arrangement of Fig. 1A projected onto the XY plane. Now, assume that the measurement origin O is at the bisecting point of the straight line connecting the two suspension points 1 and 2 of model A, and the distance between the two points is 2L ₁ . The third suspension point 3 on model A is perpendicular to the above straight line and is on an extension of the origin O,
Let the distance between the origin O and the third suspension point 3 be _L2 .

Furthermore, considering the vertical direction as the Z axis, orthogonal coordinates as shown in Figures 1A and 1B, and subscripting each multiforce detector.
Let's specify it by ij. In this case, i specifies the suspension point and j specifies one of the pair of multiforce detectors. That is, i=1-3, j=1,2. Let F _Kij (K=x,
Furthermore, the component force in the K direction of the detectors i1 and i2 is expressed as F _Ki ≡F _Ki1 +F _Ki2 .

Forces in _three directions acting on the origin O of the wind cylinder model A,
_{F Y , F Z and moments M X , M Y , M Z are F _ _} L ₁ −F _Z2 *L ₁ M _Y =F _Z3 *L ₂ M _X =−F _X1 *L ₁ +F _X2 *L ₁ −F _X3 *L ₂ .

If the suspension point i is in a more general arrangement than in Figures 1A and B, and it is expressed as (X _i , Y _i , Z _i ), the 6 component forces F _X , F _Y , F _Z with respect to the origin O of the model , M _X , M _Y ,
M _Z is _{F X} = F _X1 +F _X2 + _{F X3 F Y} =F _Y1 +F _Y2 +F _{Y3 F Z} =F _Z1 + _{F Z2} + _{F Z3 M} −F _Y1 *Z ₁ −F _Y2 *Z ₂ +F _Y3 *Z ₃ M _Y =F _X1 *Z ₁ −F _X2 *Z ₂ +F _X3 *Z ₃ −F _Z1 *X ₁ −F _Z2 *X ₂ +F _Z3 *X ₃ M _Z =F _Y1 *
X ₁ −F _Y2 *X ₂ +F _Y3 *X ₃ −F _X1 *Y ₁ −F _X2 *Y ₂ +F _X3 *Y ₃ .

FIG. 2 shows a second embodiment of a suspended support arrangement according to the invention. At suspension points 1, 2, and 3,
Weights W ₁ , W ₂ , and W ₃ are suspended vertically via wire rods, respectively. The triangular surfaces formed by the pair of detectors i1, i2 and the corresponding suspension point i are respectively XZ plane at suspension point 1, YZ plane at suspension point 2, and YZ plane at suspension point 3.
and is parallel to the YZ plane. That is, the triangular plane formed by the two wire rods and the suspension point includes a vertical line passing through the suspension point. With such an arrangement, it is sufficient that the multi-force detectors can respectively detect the vertical direction and the bicomponent force perpendicular to this direction and within the plane of the above-mentioned hanging triangle.

After all, in the arrangement shown in Figure 2, the six component forces acting on the origin O of the wind cylinder model are: F _X = F _X1 F _Y = F _Y2 + F _Y3 F _Z = F _Z1 + F _Z2 + F _Z3 M _X = (F _Z1 − F _Z2 )・L ₁ M _Y = F _Z3・L ₂ M _Z = −F _X1・L ₁ +F _Y3・L ₂ . Here, L ₁ and L ₂ are the length from the origin O to the suspension point 1 or 2 and the length to the suspension point 3, respectively, as shown in FIG.

FIG. 3 shows a third embodiment of a suspended support arrangement according to the invention. In this case, although the model is not shown, it is the same as the model in FIG. 2, and each suspension point is also the same. However, two pairs of component force detectors 11
Since the installation positions of 12, 21 and 22 are different,
This arrangement is shown projected onto the XY plane. In the case of FIG. 3, in the two pairs of detectors, the triangular planes formed by both detectors and the corresponding suspension points intersect both the XZ plane and the YZ plane. That is, each component force detector 11, 12, 21,
22, 31, and 32 are installed, and pair 1 of component force detectors is installed.
The angle between the intermediate points P1 and P2 of 1, 12 and 21, 22 and the Y axis is θ.

Even in the case of Fig. 3, component force detectors 11, 12, 2
1 and 22 are detectors capable of measuring at least two component forces, and detect a force in the Z-axis direction and a force that is within the plane of the triangle and perpendicular to the Z-axis. Denoting the latter force on the detector ij by F ^P _ij , F _Xij = F ^P _ijcps θ F _Yij = F ^P _ijsio θ .

The 6-component force acting on the model's origin O is F _X = F _X1 +F _X2 F _Y = F _Y1 +F _Y2 +F _Y3 F _{Z =} F _Z1 + _{F Z2 + F Z3 M Y} = F _Z3・L ₂ M _Z = (F _X2 −F _X1 )・L ₁ +F _Z3・L ₂ .

In the end, using the component forces calculated in the three examples, the effective six component forces acting on the model origin O are _X , _Y , _X , _X ,
To calculate M _Y , _Z , 6 detected when there is no wind
_{Let the} ^component _{forces be F} ^O _X , _F ^O _{Y , F} ^{O X} , ^M _O From _Z , resistance force _X = F _{X − F} ^O _{X Lateral} force _{Y =} F _X − F ^O _X Lift ^force _Z = F _X ⁻ _{F O} −M ^O _X Yaw moment _Z = M _X −M ^O _X.

〔Effect of the invention〕

The first diagram showing the suspension method of the wind cylinder model according to the present invention.
By comparing Figures A, 1B, 2, and 3 with Figure 4, which shows a suspension system according to the prior art, even those who are not skilled in the art can easily understand the present invention. The significant advantages of this invention are as follows.

(1) Even when the wind cylinder model is rotated, there are no fulcrums or pulleys like those used in conventional suspension systems upstream of the wind flow, so hydrodynamic characteristics can be measured over a wide range of rotation. can. In fact, it is possible to turn the model in a horizontal state by ±180°, ie in all directions (in contrast, with the conventional measurement method (Fig. 4), it is at most ±30°).

(2) Since there is no need for wire rods in the Y and X directions that are adjusted in relation to the suspension points, the troublesome and delicate initial setting of the model can be done in a short time, and this work requires almost no skill or experience. . In particular, when changing positions, the conventional method does not require any repeated adjustment of the catenary wires associated with each other.

(3) To change the attitude of the model, simply change the position of the multi-force detector that supports the suspension point; there are no mounts or support structures at the bottom or sides of the wind cylinder model, so there is no need for large-scale accessories or other support structures. No variable movement mechanism is required.

(4) From (2) and (3) above, it is possible to significantly reduce the size of the wind cylinder equipment itself and the size of the stand for changing its attitude, or if it is a certain amount of existing equipment, it is possible to test with a larger model. .

(5) Detection and detection based on initial measurements through complex procedures
No need to calibrate the measurement system.

(6) All of the above ensure a high degree of accuracy in the final test measurement results and at the same time improve reliability and reproducibility.

[Brief explanation of the drawing]

FIG. 1A is a schematic perspective view showing a first embodiment of a method for measuring the hydrodynamic characteristics of a suspended wind model according to the present invention. The arrangement of Figure 1B and Figure 1A
A plan view projected onto the XY plane. FIG. 2 is a schematic perspective view showing a second embodiment of the method for measuring the hydrodynamic characteristics of a suspended wind cylinder model according to the present invention. Third
FIG. 3 is a plan view showing a third embodiment of the method for measuring the hydrodynamic characteristics of a suspended wind cylinder model according to the present invention. FIG. 4 is a schematic perspective view illustrating a conventional method for measuring the hydrodynamic characteristics of a suspension-supported wind cylinder model. Reference numbers in the figure, 1, 2, 3...suspension point, A...
Wind fuselage model, W ₁ , W ₂ , W ₃ ... Weight, Q ₁ , Q ₂ ...
Pulley, C ₁ , C ₂ , C ₃ ... fulcrum, G ₁ , G ₂ , G ₃ ... fixed point.

Claims (1)

[Claims] 1. Three pairs of fixed points 11, 12, 21, 22, 31, 32 are provided on the frame of the mount in the wind cylinder, and one multi-force detector is fixed to each fixed point. Then, by using a wire connected to each detector, the three suspension points 1, 2, and 3 of the wind cylinder model A, which are arranged corresponding to the three sets of fixed points, are suspended,
The wind cylinder model is suspended and supported in a desired posture so that the wire rod is under tension in no wind and test airflow due to the weight of the model, and the measured force detected by each detector in no wind is applied to the origin of the wind cylinder model. Calculate the force and/or moment of three orthogonal components, calculate the force and/or moment of three orthogonal components acting on the origin of the wind cylinder model from the measured force components detected by each detector under the wind during the test, A method for measuring the hydrodynamic characteristics of a suspended wind cylinder model, the method comprising calculating an effective force and/or moment acting on the wind cylinder model from both forces and/or moments. 2. A triangular plane formed by a suspension point and two fixed points corresponding to this suspension point includes a straight line in the vertical direction, and a multi-force detector corresponding to the fixed point is perpendicular to the vertical direction and this direction, and the triangular plane includes a straight line in the vertical direction. 2. The method according to claim 1, wherein only force components in two directions within the range can be measured. 3. The method according to claim 1 or 2, wherein the weight of the wind cylinder model is equal to the weight of the wind cylinder model itself. 4. The weight of the wind cylinder model is equal to the sum of the weight of the wind cylinder model itself and the weight of the weight installed inside this wind cylinder model A or the weight suspended from the wind cylinder model A. The method according to claim 1 or 2, wherein: