CN-122019919-A - Air-cooled turbine efficiency correction method considering change of air-cooled temperature ratio

CN122019919ACN 122019919 ACN122019919 ACN 122019919ACN-122019919-A

Abstract

The invention discloses an air-cooled turbine efficiency correction method considering the change of the temperature ratio of cold air, which comprises the steps of implementing a reference test with the total temperature ratio of 1 to obtain reference efficiency Implementing a total temperature ratio of Is actually low-temperature tested to obtain the efficiency Constructing non-isothermal heat transfer entropy product calculation models, and respectively calculating the total temperature ratio as Temporal cold air and mainstream blending entropy production The total temperature ratio to the actual operating conditions is Temporal cold air and mainstream blending entropy production Calculating to obtain the total temperature ratio of the actual working condition as Correction efficiency at time . The method innovatively introduces the entropy production theory to construct the correction model, thoroughly overcomes the defects of weak theoretical basis and incomplete loss consideration of the existing method, does not need extreme low-temperature test conditions, greatly reduces equipment cost and safety risk, and improves engineering feasibility and economy.

Inventors

ZHANG WEIHAO
WANG PENGHUI
DENG JI

Assignees

北京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20260124

Claims (5)

1. An air-cooled turbine efficiency correction method considering a change in a temperature ratio of cold air, comprising: S1, performing a reference test with a total temperature ratio of 1, namely, a reference test with a total temperature of cold air equal to a total temperature of a main stream, and calculating reference efficiency according to test results ; S2, based on the actual conditions of the test equipment, the minimum total temperature ratio achieved by implementation is According to the actual low temperature test of the working condition, calculating the efficiency of the working condition ; S3, constructing a non-isothermal heat transfer entropy production calculation model, and respectively calculating the total temperature ratio as Temporal cold air and mainstream blending entropy production And the total temperature ratio of the actual working condition is Temporal cold air and mainstream blending entropy production ; S4, based on linear entropy production assumption and loss invariant assumption, utilizing reference efficiency The total temperature ratio is Efficiency at time 、 And The total temperature ratio of the actual working condition is calculated and obtained by correcting the formula Correction efficiency at time 。
2. The method for correcting the efficiency of an air-cooled turbine taking into account a change in the temperature ratio of cold air according to claim 1, wherein said step S1 further comprises the substeps of: S101, constructing a blending entropy increment decomposition model, and increasing the total entropy of the blending process of the cold air and the main flow in the air-cooled turbine Divided into three items, which are respectively entropy increment caused by non-isothermal heat transfer between cold air and main stream gas Entropy increase due to total drop caused by blending And entropy increment of main stream gas and cold gas caused by different gas types As a theoretical framework for subsequent loss calculations, wherein, Recording device , Is marked as , Is marked as ; S102, setting an entropy increase constraint condition of a reference working condition, based on the condition that the main flow and the cold air are the same gas working medium, the method enables At the same time assume The blending loss between the cold air and the main flow is set to be only the entropy increment caused by non-isothermal heat transfer between the cold air and the main flow gas when the temperature ratio of the cold air is changed Leading; S103, setting Will be Divided into temperature differences And differential pressure dominant And dividing the efficiency into three terms, wherein the mathematical expression of the efficiency is as follows: (1); s104, setting total reduced isentropic work The total reduced isentropic work is kept unchanged when the total temperature of the cold air is different under the same cold air quantity without changing along with the total temperature of the cold air, so that the second term in the mathematical expression of the efficiency under the same cold air quantity The total temperature of the cold air is not changed; S105, order Calculating the reference efficiency of the reference test with the total temperature ratio of 1 Reference efficiency The calculated expression of (2) is: (2) Wherein, the Indicating the loss of the cold air and the main flow in the expansion working process of the turbine runner, Indicating the loss of total pressure drop caused by blending of cold air with the main stream.
3. The method for correcting the efficiency of an air-cooled turbine taking into account a change in the temperature ratio of cold air according to claim 2, wherein said step S2 further comprises the substeps of: s201, determining the minimum cold air temperature and the main flow temperature adjusting range of the test equipment capable of stably running for a long time, determining the test boundary constraint, and calculating the minimum practical total temperature ratio according to the equipment limit capacity ; S202, assuming that the total temperature of the cold air is different, the loss of the cold air and the main flow in the expansion work process of the turbine runner is respectively caused When the total temperature of the cold air is unchanged, only the last term exists in the mathematical expression of the efficiency The mathematical expression of the efficiency can be modified at this time to: (3); Wherein, let the Obtaining the total temperature ratio of Efficiency at time And a total temperature ratio of Efficiency at time The method comprises the following steps of: (4)。
4. The air-cooled turbine efficiency correction method considering the variation of the air-cooled temperature ratio according to claim 3, wherein said step S3 further comprises the substeps of: S301, constructing a non-isothermal heat transfer entropy production calculation model, wherein the mathematical expression of the non-isothermal heat transfer entropy production calculation model is as follows: (5); s302, according to mathematical expression of the non-isothermal heat transfer entropy product calculation model, respectively calculating to obtain a total temperature ratio of Temporal cold air and mainstream blending entropy production And the total temperature ratio of the actual working condition is Temporal cold air and mainstream blending entropy production The mathematical expressions are respectively as follows: (6) (7)。
5. The method for correcting the efficiency of an air-cooled turbine taking into account a change in the temperature ratio of cold air according to claim 4, wherein said step S4 further comprises the substeps of: s401, setting total reduced isentropic work On the premise of not changing with the total temperature of the cold air, the reference efficiency is combined The total temperature ratio is Efficiency at time 、 And The total temperature ratio of the actual working condition is obtained by correcting the formula Time efficiency The expression of (2) is: (8); S402, setting The total temperature ratio of the actual working condition is obtained as Efficiency at time Efficiency correction formula of (a) The method comprises the following steps: (9)。

Description

Air-cooled turbine efficiency correction method considering change of air-cooled temperature ratio Technical Field The invention relates to the technical field of air-cooled turbine aerodynamic performance correction, in particular to an air-cooled turbine efficiency correction method considering the change of the temperature ratio of cold air. Background With the improvement of the thrust requirement of the aero-engine, the front temperature of the high-pressure turbine exceeds the melting point of high-temperature alloy used by the turbine blades, and the turbine blades need to adopt various cooling designs, wherein a cooling air film is a key means, and can effectively isolate the blades from a high-temperature main stream. In the design of aeroengines, turbine aerodynamics tests are indispensable for verifying design schemes and evaluating feedback aerodynamic designs, which complement the tests. However, the extreme of the working environment of the high-pressure turbine makes the full-temperature full-pressure test difficult, high in cost and difficult to ensure safety, so that the component test is usually carried out in a medium-low temperature environment, and the difference exists between the test environment and the actual working environment, so that the similarity of the turbine flow field and the performance is affected. In order to ensure the similarity of the flow field and the performance, the test can select similar parameters, but for a high-pressure air-cooled turbine, the total temperature ratio of the cold air and the main flow is difficult to ensure to be consistent, the similarity is destroyed, the efficiency of the test data and the actual working condition is different, and the authenticity and the reliability of the test result are reduced. Specifically, for the high-pressure air-cooled turbine, when the specific heat ratio, re, expansion ratio and folding rotation speed, and the total temperature ratio and flow ratio (total pressure ratio) of cold air and main flow are ensured, the similarity of the performance of the turbine under a low-temperature test and the performance of the turbine under a flow field and an actual working condition can be ensured. However, the main flow of the high-pressure air-cooled turbine is at a lower temperature, and if the temperature ratio of the cold air to the main flow is to be ensured, the cold air is at a lower temperature, and it is difficult to realize long-term stable cold air supply at such temperature in practical experiments. In the current test, two main findings and schemes exist, namely, the early research considers that the temperature ratio has small influence and can be ignored, but the method is in question due to the fact that the method is in theoretical lack of support along with the improvement of the test precision requirement. Secondly, part of researches are considered to be from the point of a blending loss forming mechanism, the momentum ratio of the main flow and the cold air is guaranteed to be consistent, but the method of guaranteeing the momentum ratio only considers the momentum exchange loss caused by the speed difference, does not consider the internal energy exchange loss caused by the temperature difference, and still has obvious defect in consideration of the convection field loss. In summary, when the temperature ratio problem in the high-pressure air-cooled turbine test is processed in the prior art, the problems that theoretical support is insufficient and the accuracy requirement is difficult to meet in practice exist, meanwhile, consideration of flow field loss is also incomplete, and the current high requirements on the authenticity and reliability of the test result are difficult to meet. Disclosure of Invention The embodiment of the invention provides an air-cooled turbine efficiency correction method considering the change of a cold air temperature ratio, which aims to solve the technical problem that the total temperature ratio of cold air/main flow is inconsistent with an actual working condition and further causes significant deviation between test efficiency and real performance because the cold air temperature cannot be reduced to an extremely low level required by a similar rule in a high-pressure air-cooled turbine test, and the problem cannot meet the current requirement on increasing test precision because the prior method completely ignores the influence of the temperature ratio or only considers the internal energy exchange loss caused by the missing temperature difference due to the similarity of the momentum ratio. An air-cooled turbine efficiency correction method considering a change in a temperature ratio of cold air, comprising: S1, performing a reference test with a total temperature ratio of 1, namely, a reference test with a total temperature of cold air equal to a total temperature of a main stream, and calculating reference efficiency according to test results ; S2, based on the a