CN114544133A - Similar method for turbine variable working medium test - Google Patents

Similar method for turbine variable working medium test Download PDF

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CN114544133A
CN114544133A CN202210164851.4A CN202210164851A CN114544133A CN 114544133 A CN114544133 A CN 114544133A CN 202210164851 A CN202210164851 A CN 202210164851A CN 114544133 A CN114544133 A CN 114544133A
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working
working condition
working medium
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inlet
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张伟昊
王鹏辉
穆雨墨
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Beihang University
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    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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 provides a similar method for a turbine variable working medium test, which gives a similar criterion suitable for different working media, and obtains the total inlet pressure, the total outlet pressure and the rotating speed of a simulated working condition using a working medium B by conversion of the similar criterion, thereby setting inlet and outlet parameters and the rotating speed of the simulated working condition to ensure that the result of the simulated working condition accurately reflects the flow field and the performance of the prototype working condition using the working medium A; the similar criteria are as follows:
Figure DDA0003515912760000011
2. reduced rotational speed with specific heat ratio correction taken into account
Figure DDA0003515912760000012
3. Reynolds number Re.

Description

Similar method for turbine variable working medium test
Technical Field
The invention relates to a similar method for a turbine variable working medium test, and belongs to the technical field of special working medium turbines.
Background
At present, special working medium turbines are widely applied to various engineering fields, including but not limited to helium turbines and supercritical CO turbines of power generation systems2Turbines, organic working medium (R123, R245a and the like) turbines and the like of the rocket propulsion system (the special working medium turbine refers to a turbine with a working medium which is not air). In the development process of the turbine, the impeller machine is required to be processed according to a design scheme, and a simulation test of the flow field and the performance of the turbine is required to be carried outAnd optimizing the design scheme according to the test result to ensure that the finally designed turbine can reach the design target.
The simulation test of the flow field and performance of the turbine stage is carried out on a rotary test bed, according to a specified similar method, parameters of an inlet and an outlet of the test and the rotating speed of a turbine rotor are set, then the test is started, and the flow field parameters (total temperature, total pressure, speed and the like) of the turbine and the output power (measured by a dynamometer) of the turbine are measured in the test. However, the internal working environment of some special working medium turbines is extremely severe, such as some supercritical CO2The total temperature of the turbine is more than 900K, the pressure is more than 7.5MPa, but the simulation test shows that if the supercritical CO is directly used2When the working medium is used for testing the turbine, on one hand, the temperature and the pressure are difficult to realize in a simulation test, and the test cost is too high, on the other hand, the flow field parameters are difficult to accurately measure under the temperature and the pressure, and the test result under the condition cannot be specifically fed back to a designer. In response to these problems, experimenters wish to find a reliable and similar method for conducting simulation tests under low temperature and low pressure conditions using air (or other simple and safe working fluid) as the working fluid for testing the turbine.
The similar method refers to the supercritical CO in the known prototype2Under the conditions of total inlet temperature and total pressure, total outlet pressure and rotating speed of the turbine, the total inlet pressure, the total outlet pressure and the rotating speed of the simulation test can be converted according to similar criteria, so that inlet and outlet parameters and the rotating speed of the simulation test are set. Therefore, the core of the similarity method is the similarity criterion, and if the similarity criterion is not reasonable, the result of the simulation test cannot accurately reflect the flow field and the performance of the prototype turbine. In the simulation test, air is generally used to replace a special working medium for the test, but the physical properties of different working media are different, so that a reasonable similarity criterion suitable for different working media is selected.
In the technical scheme of the prior art:
1. for the same working medium, the existing similar method takes expansion ratio, reduced rotating speed and Re as similar criteria, and has the technical defects that the total inlet temperature under the test working condition is lower than that under the prototype working condition, but the influence of the specific heat ratio is not considered in the similar method;
2. for different working fluids, Den (Den g., Malyshev a.. Modeling of the Flow Parts of static central Compressor mechanisms for Compression of Real gases. gasdynamic Tests and Processing of the theory of turbine results. i.e. theoretical considerations [ J ]. Journal of Engineering Physics & thermodynamics, 2002,75(5): 1076:1085) discussed the effects of St, Re, Pr, Eu, Fr on turbine Flow fields, and proposed that these five similar criteria numbers are the similar criteria for turbines, but these criteria numbers are not really guaranteed at the same time, and thus cannot be directly applied to the similar design of turbine model.
Zhu et al (Zhu Rongkai, Wang Jie, Zhung Qun, et al. off-Design Performance Research of an Axial Helium Compressor for HTGR-10Power Conversion Unit [ J ]. Nuclear Engineering and Design,2010,240(10): 2914) 2919) in the study of Helium-to-air working fluid similarity of Axial flow compressors, St, Eu and Re were used as the similarity criteria, the resulting experimental efficiency was closer to the prototype efficiency. However, in the derivation of the similarity criterion, the assumption that the total temperature ratio of the helium gas working medium to the air working medium is approximately equal to the static temperature ratio is used, so that the similarity criterion is only applicable to the case of low Ma, and when Ma is higher, the assumption causes larger deviation.
Disclosure of Invention
The invention aims to enable the working condition of working medium B to more accurately reflect the flow field and performance of the working condition of working medium A on the premise of geometric similarity.
The method is to establish a new similar method: and reasonably providing a new similarity criterion suitable for different working mediums, and converting by using the new similarity criterion to obtain the total inlet pressure, the total outlet pressure and the rotating speed of the simulated working condition using the working medium B, thereby setting the inlet and outlet parameters and the rotating speed of the simulated working condition to ensure that the result of the simulated working condition can accurately reflect the flow field and the performance of the prototype working condition using the working medium A.
Under the assumptions of steady state, thermal insulation, compressibility and neglect of the influence of working medium gravity, parameters influencing the flow and performance of the turbine flow field include:
mechanical parameters: mean diameter D of stages, rotor speed n
Physical parameters of the fluid: gas constant R, kinetic viscosity coefficient mu, specific heat ratio gamma
Flow state parameters: total temperature of main stream inlet
Figure BDA0003515912740000021
Total pressure of main flow inlet
Figure BDA0003515912740000022
Main flow rate G, total pressure at turbine outlet
Figure BDA0003515912740000023
Wheel characteristic parameters: efficiency η, power P
The above 11 physical quantities have the relationship:
Figure BDA0003515912740000024
according to the dimension analysis method, the final product can be obtained
Figure BDA0003515912740000025
Wherein
Efficiency of
Figure BDA0003515912740000026
Reduced power
Figure BDA0003515912740000027
Reduced flow
Figure BDA0003515912740000031
1. Folding rotation speed
Figure BDA0003515912740000032
2. Expansion ratio
Figure BDA0003515912740000033
3. The specific heat ratio gamma;
4. reynolds number
Figure BDA0003515912740000034
Namely, on the premise of geometric similarity, when the four similarity criteria are ensured to be unchanged, the efficiency, the reduced power and the reduced flow of the turbine can be ensured to be unchanged. However, physical parameters of different working media, namely a gas constant R and a specific heat ratio gamma, are different greatly, so that the similar criterion of the specific heat ratio is not equal any more in the turbine similarity problems of different working media, and if only the other three similar criteria are ensured to be equal, the flow fields and the performances of two turbines using different working conditions of different working media have larger deviation (the old similar method is the three similar criteria), so that a new similar criterion aiming at different working media needs to be used, and the main method is to consider the correction of the inequality of the specific heat ratio on other similar criteria. Two working mediums A and B are respectively used for the turbines with similar geometry, the working condition of using the working medium A is recorded as working condition A, and the working condition of using the working medium B is recorded as working condition B. According to the circumferential lambda number-lambda of the inlet of the movable bladeuCan be expressed as:
Figure BDA0003515912740000035
wherein
Figure BDA0003515912740000036
Is constant, so long as it guarantees
Figure BDA0003515912740000037
Equality, i.e. λ is guaranteeduAre equal. Compared to the aforementioned reduced rotational speed
Figure BDA0003515912740000038
The specific heat ratio is included, so that the method is suitable for similarity among different working mediums.
In addition, according to the aforementioned:
efficiency of
Figure BDA0003515912740000039
Reduced power
Figure BDA00035159127400000310
Reduced flow
Figure BDA0003515912740000041
Combining the three to obtain
Figure BDA0003515912740000042
Due to eta,
Figure BDA0003515912740000043
All are functions of specific heat ratio, reduced rotation speed, Re and expansion ratio, and are obtained after the three are combined
Figure BDA0003515912740000044
Can also be expressed as:
Figure BDA0003515912740000045
it is obvious that
Figure BDA0003515912740000046
And is also a physical quantity including the influence of the specific heat ratio and the expansion ratio. Then to
Figure BDA0003515912740000047
As a new similarity criterion, instead of the expansion ratio, the influence of the specific heat ratio can be taken into account in this similarity criterion.
Since Re reflects the effect of the viscosity of the fluid, this similarity criterion is not adjusted.
In conclusion, aiming at similar problems of different working mediums, a new similarity criterion is provided:
1.
Figure BDA0003515912740000048
2. reduced rotational speed with specific heat ratio correction taken into account
Figure BDA0003515912740000049
3. Reynolds number Re;
according to the total inlet temperature and total pressure, the total outlet pressure and the rotating speed of the working condition A and the total inlet temperature of the working condition B, the total inlet pressure, the total outlet pressure and the rotating speed of the working condition B can be obtained by using the three similar criteria.
Specifically, the method comprises the following steps:
the total inlet temperature of the known working condition A
Figure BDA00035159127400000410
And a rotational speed nAAnd inlet total temperature of operating mode B
Figure BDA00035159127400000411
In addition, the reduced rotating speed of the working condition A and the working condition B which is corrected by considering the specific heat ratio is equal to one of the following conditions:
Figure BDA00035159127400000412
wherein, the specific heat ratio gamma and the gas constant R of the working medium A and the working medium B are the physical properties of the working medium, and the specific heat ratios and the gas constants of different working media can be found in a material library; obtaining the rotating speed n which should be set under the working condition B according to the known parameters and the formulaB；
The total inlet temperature of the known working condition A
Figure BDA00035159127400000413
Inlet total pressure
Figure BDA00035159127400000414
Total pressure at the outlet
Figure BDA00035159127400000415
And inlet total temperature of operating mode B
Figure BDA00035159127400000416
In addition, the Re of the working condition A is equal to that of the working condition B, and the working conditions comprise:
Figure BDA00035159127400000417
wherein the dynamic viscosity mu of the working medium A and the working medium B is also the physical property of the working medium and is found in a material library; determining the total inlet pressure of the working condition B according to the known parameters and the formula
Figure BDA0003515912740000051
With further operation A and B
Figure BDA0003515912740000052
Equality, determining total outlet pressure under working condition B
Figure BDA0003515912740000053
And finally, performing numerical simulation or pneumatic performance test on the working condition B by obtaining the total temperature of the inlet, the total pressure of the outlet and the rotating speed of the turbine which are required to be set under the working condition B.
Drawings
FIG. 1 shows that the outlets Ma of the movable blades under various working conditions of the embodiment are distributed along the spanwise direction;
FIG. 2 shows the distribution of the blade outlet flow angles in the span-wise direction under various working conditions of the embodiment.
Detailed Description
The specific technical scheme of the invention is described by combining the embodiment.
Using a certain type of turbine to carry out numerical simulation, using fuel gas with oil-gas ratio of 0.021 as working medium A, and using supercritical CO2As working substance B, AAlkane CH4Helium He serves as working medium D. After boundary conditions of working conditions using gas working media are given and numerical simulation is carried out, old similar methods and new similar methods provided by the invention are respectively used for conversion to obtain the supercritical CO2The distribution of the turbine rotor blade outlet Ma and the airflow angle in the spanwise direction is obtained as shown in fig. 1, and the results show that compared with the prior similar method: the expansion ratio, the reduced rotation speed and the working conditions B1, C1 and D1 obtained by Re, and the distribution of the movable blade outlets Ma and the airflow angles of the working conditions B2, C2 and D2 obtained by the novel similar method provided by the invention along the spanwise direction are shown in figure 2, and are obviously closer to the working condition A using the gas working medium.
From the turbine efficiency obtained by numerical simulation, the efficiency of the operating condition a using the gas working medium was 88.16%, and the efficiency obtained using the old similar method using supercritical CO was obtained2Working condition D1 of working medium has efficiency of 86.98%, and supercritical CO is used by using a new similar method2The efficiency of working medium working condition D2 is 87.74%, the efficiency deviation of working condition D1 from working condition A is-1.18%, and the efficiency deviation of working condition D2 from working condition A is only-0.42%.
In summary, using a new similar approach, supercritical CO can be used2、CH4And the flow field and efficiency of the working condition of the He working medium are closer to those of the working condition of using the gas working medium.

Claims (5)

1. A similar method for a turbine variable working medium test is characterized in that a similar criterion suitable for different working media is given, and the total inlet pressure, the total outlet pressure and the rotating speed of a simulated working condition using a working medium B are obtained by conversion of the similar criterion, so that the inlet and outlet parameters and the rotating speed of the simulated working condition are set;
the similar criteria are as follows:
1.
Figure FDA0003515912730000011
2. reduced rotation speed corrected by considering specific heat ratio
Figure FDA0003515912730000012
Average diameter D, rotor speed n, gas constant R, specific heat ratio gamma, total temperature of main flow inlet
Figure FDA0003515912730000013
3. Reynolds number Re.
2. The similar method for the turbine variable working medium test is characterized by comprising the following steps of:
the total inlet temperature of the known working condition A
Figure FDA0003515912730000014
And a rotational speed nAAnd inlet total temperature of operating mode B
Figure FDA0003515912730000015
In addition, the reduced rotating speed of the working condition A and the working condition B which is corrected by considering the specific heat ratio is equal to one of the following conditions:
Figure FDA0003515912730000016
wherein, the specific heat ratio gamma and the gas constant R of the working medium A and the working medium B are the physical properties of the working medium, and the specific heat ratios and the gas constants of different working media can be found in a material library; obtaining the rotating speed n which should be set under the working condition B according to the known parameters and the formulaB。
3. The similar method for the turbine variable working medium test is characterized by comprising the following steps of:
the total inlet temperature of the known working condition A
Figure FDA0003515912730000017
Inlet total pressure
Figure FDA0003515912730000018
Total pressure at the outlet
Figure FDA0003515912730000019
And inlet total temperature of operating mode B
Figure FDA00035159127300000110
In addition, the Re of the working condition A is equal to that of the working condition B, and the working conditions comprise:
Figure FDA00035159127300000111
wherein the dynamic viscosity mu of the working medium A and the working medium B is also the physical property of the working medium and is found in a material library; determining the total inlet pressure of the working condition B according to the known parameters and the formula
Figure FDA00035159127300000112
4. The similar method for the turbine variable working medium test is characterized by comprising the following steps of: with further operation A and B
Figure FDA00035159127300000113
Equality, determining total outlet pressure under working condition B
Figure FDA00035159127300000114
5. The similar method for the turbine variable working medium test is characterized by comprising the following steps of: and finally, performing numerical simulation or pneumatic performance test on the working condition B by obtaining the total temperature of the inlet, the total pressure of the outlet and the rotating speed of the turbine which are required to be set under the working condition B.
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Publication number Priority date Publication date Assignee Title
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US20200217749A1 (en) * 2018-07-18 2020-07-09 Dalian University Of Technology Parmeter similarity method for test simulation conditions of aerodynamic heating environment
CN113962027A (en) * 2021-10-26 2022-01-21 北京航空航天大学 Method and device for determining turbine similarity test conditions and storage medium
CN114021271A (en) * 2021-10-22 2022-02-08 北京航空航天大学 Gas turbine performance test result correction method and device considering Reynolds number effect

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200217749A1 (en) * 2018-07-18 2020-07-09 Dalian University Of Technology Parmeter similarity method for test simulation conditions of aerodynamic heating environment
CN111062124A (en) * 2019-12-05 2020-04-24 西安交通大学 Similar modeling method for supercritical carbon dioxide compressor test
CN114021271A (en) * 2021-10-22 2022-02-08 北京航空航天大学 Gas turbine performance test result correction method and device considering Reynolds number effect
CN113962027A (en) * 2021-10-26 2022-01-21 北京航空航天大学 Method and device for determining turbine similarity test conditions and storage medium

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Application publication date: 20220527