A performance calculation method for counter-rotating propeller fans considering installation effects

Abstract

The present invention discloses a method for calculating the performance of a counter-rotating propeller fan considering the installation effect, which belongs to the field of aero-engines. First, the inlet conditions of the front row propeller fan are calculated, and then the installation effect correction of the front row propeller fan pitch ratio is performed, and then the front row propeller fan characteristic diagram is interpolated to obtain the efficiency and power coefficient of the front row propeller fan, and then the efficiency is corrected for the installation effect, and the self-induced speed and mutual-induced speed generated by the front row propeller fan are calculated; then the inlet conditions of the rear row propeller fan are calculated, the installation effect correction of the rear row propeller fan pitch ratio is performed and the rear row propeller fan characteristic diagram is interpolated to obtain the efficiency and power coefficient of the rear row propeller fan, and then the efficiency is corrected for the installation effect, and the self-induced speed and mutual-induced speed generated by the rear row propeller fan are calculated; when the overall iteration of the calculation model converges, the performance calculation of the counter-rotating propeller fan considering the installation effect is completed. The problem that the conventional counter-rotating propeller fan performance calculation method cannot consider the installation resistance generated by the propeller slipstream effect is solved.

Description

Technical Field

[0001] The invention belongs to the field of aviation engines, and in particular relates to a method for calculating the performance of a counter-rotating propeller fan taking installation effects into consideration. Background Art

[0002] The CPF engine combines the low fuel consumption of the turboprop engine and the high flight speed of the turbofan engine, and is one of the ideal engines for the new generation of military transport aircraft and commercial aircraft. The CPF engine is the main thrust source of the CPF engine. Compared with the turbofan engine, the CPF engine, which is the main thrust source of the CPF engine, has a larger diameter than the fan and no external duct. Therefore, the aerodynamic coupling between the CPF engine and the aircraft wing / fuselage is very close. When calculating the performance of the CPF engine, the impact of the installation effect cannot be ignored.

[0003] In the current calculation of the overall performance of a counter-rotating propfan engine, the performance calculation of the counter-rotating propfan components often does not take into account the losses caused by the installation effect. Moreover, the counter-rotating propfan performance calculation method applicable to the overall performance calculation of a counter-rotating propfan engine often does not fully consider the influence of the induced velocity between the front and rear rows of propellers for the purpose of simplifying the calculation, and ignores the flow tube contraction of the circumferential induced velocity. Therefore, it is necessary to develop a counter-rotating propfan performance calculation method that can consider the installation effect of the counter-rotating propfan and fully consider the influence of the induced velocity, so as to improve the calculation accuracy of the counter-rotating propfan components and the overall performance model of the counter-rotating propfan engine. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a method for calculating the performance of counter-rotating propellers taking into account the installation effect, so as to solve the problem that the overall performance model of the counter-rotating propeller engine in the prior art does not take into account the installation effect when calculating the performance of the counter-rotating propeller components and does not fully consider the influence of the induced speed between the front and rear rows of propellers.

[0006] The technical solution of the present invention is: a method for calculating the performance of a counter-rotating propeller fan taking into account the installation effect, characterized in that the specific steps are as follows:

[0007] Step 1: Given the axial mutual induced velocity V of the rear propeller fan to the front propeller fan ind21 and the circumferential mutual induced velocity ω ind21 The initial guess value V′ ind21 and ω′ ind21 ; And calculate the front row propeller fan inlet conditions, that is, the actual inlet axial speed V1 and pitch ratio J1 of the front row propeller fan;

[0008] Step 2: Correct the front row propeller pitch ratio J1 for installation effect. The formula is:

[0009]

[0010] Among them, S Na is the cross-sectional area of ​​the engine nacelle in the propeller slipstream area, D1 is the diameter of the front row propeller fan;

[0011] Step 3: Interpolate the efficiency η of the front propeller fan from the characteristic diagram using the corrected pitch ratio J1′ and pitch angle 1map and power factor;

[0012] Step 4: Correct the front propeller fan efficiency for installation effects using the formula:

[0013]

[0014] Among them, C Dap , C DTa , C DFu and C DNa Respectively represent the drag coefficients of the aircraft wing, tail, fuselage and engine nacelle, S ap , S Ta , S Fu and S Na are the cross-sectional areas of the aircraft wing, tail, fuselage and engine nacelle in the propeller slipstream region, η 1map and η 1real They are the characteristic diagram efficiency and actual efficiency of the front propeller fan respectively;

[0015] Step 5: Calculate the self-induced axial velocity V of the front propeller ind11 and the angular velocity ω ind11 ;

[0016] Step 6: Calculate the mutual induced axial velocity V of the front propeller fan on the rear propeller fan ind12 ;

[0017] Step 7: Calculate the actual inlet axial velocity V2 and pitch ratio J2 of the rear propeller fan;

[0018] Step 8: Calculate the mutual induced circumferential angular velocity ω of the front propeller fan to the rear propeller fan ind12 , the formula is:

[0019]

[0020] Among them, A1 is the flow area of ​​the front row propeller fan, R1 is the radius of the front row propeller fan, K1 is the correction coefficient, R 2h is the hub radius of the rear propeller fan;

[0021] Step 9: Correct the installation effect of the rear propeller pitch ratio using the formula:

[0022]

[0023] Wherein, D2 is the diameter of the rear propeller fan;

[0024] Step 10: The efficiency η of the rear propeller fan is obtained by interpolating the corrected pitch ratio J2′ and the pitch angle from the characteristic diagram. 2map and power factor;

[0025] Step 11: Correct the rear propeller fan efficiency for installation effects using the formula:

[0026]

[0027] Among them, η 2map and η 2real They are the characteristic diagram efficiency and actual efficiency of the rear propeller fan respectively;

[0028] Step 12: Calculate the self-induced axial velocity V of the rear propeller fan ind22 and the angular velocity ω ind22 ;

[0029] Step 13: Calculate the mutual induced axial velocity V of the rear propeller fan on the front propeller fan ind21 and the angular velocity ω ind21 , the formula is:

[0030]

[0031]

[0032] Among them, A2 is the flow area of ​​the rear propeller fan, and K2 is the correction coefficient;

[0033] Step 14: Determine the calculated mutual induced axial velocity V of the rear propeller fan on the front propeller fan ind21 , circumferential angular velocity ω ind21 Is it consistent with the initial guess? If not, iterate until convergence to complete the calculation.

[0034] A further technical solution of the present invention is: in step 1, the formula for calculating the actual inlet axial velocity V1 and pitch ratio J1 of the front row propeller fan is:

[0035] V1=V0+V′ ind21

[0036] J1=V1 / ((N1+ω′ ind21 / 2π)·2R1)

[0037] Wherein, V0 is the free flow velocity, R1 is the radius of the front row propeller, N1 is the speed of the front row propeller, and π is a constant.

[0038] A further technical solution of the present invention is: in step 5, firstly, according to the power coefficient obtained in step 3 and the actual efficiency η of the front propeller fan obtained in step 4, 1real Calculate the performance parameters of the front propeller fan, namely power P1, thrust T1 and torque Q1;

[0039] Then, calculate the self-induced axial velocity V of the front propeller ind11 and the angular velocity ω ind11 , the formula is as follows:

[0040]

[0041]

[0042] Where ρ is the air density, R 1h is the hub radius of the front propeller.

[0043] A further technical solution of the present invention is: in step 6, the mutually induced axial velocity V of the front row propeller fan to the rear row propeller fan is calculated ind12 The formula is:

[0044]

[0045] Among them, Z 12 The distance between the front and rear rows of propeller fans.

[0046] A further technical solution of the present invention is: in step 7, the actual inlet axial velocity V2 and pitch ratio J2 of the rear-row propeller fan are calculated, and the formulas are:

[0047] V2=V0+V ind12

[0048] J2=V2 / ((N2+ω ind12 / 2π)·2R2)

[0049] Among them, R2 is the radius of the rear propeller fan, and N2 is the speed of the rear propeller fan.

[0050] A further technical solution of the present invention is: in step 12, firstly, according to the power coefficient obtained in step 10 and the actual efficiency η of the rear propeller fan obtained in step 11, 2real Calculate the performance parameters of the front propeller fan, namely power P2, thrust T2 and torque Q2;

[0051] Then, calculate the self-induced axial velocity V of the rear propeller fan ind22 and the angular velocity ω ind22 , the formula is:

[0052]

[0053]

[0054] Beneficial Effects

[0055] The beneficial effect of the present invention is that the application of the counter-rotating propeller performance calculation method considering the installation effect of the present invention can overcome the problem that the overall performance model of the counter-rotating propeller engine in the prior art does not consider the installation effect when calculating the performance of the counter-rotating propeller components and does not fully consider the influence of the induced speed between the front and rear rows of propellers, thereby improving the calculation accuracy of the counter-rotating propeller components and the overall performance model of the counter-rotating propeller engine.

[0056] Specifically, the current overall performance model of the CPF engine cannot take into account the installation effect of the interaction between the CPF, the engine and the aircraft when calculating the CPF performance, resulting in a theoretical difference between the calculated CPF engine performance and the actual performance. The present invention takes this installation effect into account and can complete the calculation of the CPF engine installation performance (such as Figure 1 The thrust comparison of the counter-rotating propfan engine with and without considering the installation effect is given. At the same time, the influence of the axial and circumferential induced speeds of the front and rear rows of propfans is considered in the model, which is closer to the actual operating conditions and improves the calculation accuracy of the component and engine performance model. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is the thrust comparison of the CPF engine calculated with and without considering the installation effect;

[0058] Figure 2 It is a schematic diagram of a wing-mounted pull-in type counter-rotating propfan engine and an aircraft structure in an embodiment of the present invention;

[0059] Figure 3 is a flow chart of a method for calculating the performance of a counter-rotating propeller fan taking into account installation effects in an embodiment of the present invention;

[0060] Figure 4 It is the speed triangle of the counter-rotating propeller fan performance calculation method. DETAILED DESCRIPTION

[0061] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0062] Taking the pull-in counter-rotating propfan engine installed on the wing as an example, the performance calculation method of the counter-rotating propfan considering the installation effect is introduced. The installation form and engine structure are as follows: Figure 2 As shown in the figure, due to the propeller slipstream, the nacelle of the contra-propeller fan engine, part of the aircraft's wings, tail and fuselage are all in the propeller slipstream, and the installation effect has a greater impact.

[0063] The specific embodiment of the solution of the present invention comprises the following steps. The overall process of calculating the performance of the counter-rotating propeller fan is as follows: Figure 3 As shown in the figure, the speed triangle of the counter-rotating propeller fan performance is calculated as Figure 4 shown.

[0064] This embodiment provides a method for calculating the performance of a counter-rotating propeller fan taking into account the installation effect, and the specific steps are as follows:

[0065] Step 1: Given the axial mutual induced velocity V of the rear propeller fan to the front propeller fan ind21 and the circumferential mutual induced velocity ω ind21 The initial guess value V′ ind21 and ω′ ind21 , and calculate the actual inlet axial velocity V1 and pitch ratio J1 of the front row propeller fan.

[0066] V1=V0+V′ ind21

[0067] J1=V1 / ((N1+ω′ ind21 / 2π)·2R1)

[0068] Wherein, V0 is the free flow velocity, R1 is the radius of the front row propeller, N1 is the speed of the front row propeller, and π is a constant.

[0069] Step 2: Correct the installation effect of the front row propeller pitch ratio.

[0070]

[0071] Among them, S Na is the cross-sectional area of ​​the engine nacelle in the propeller slipstream area, and D1 is the diameter of the front propeller fan.

[0072] Step 3: Interpolate the efficiency η of the front row propeller fan from the characteristic diagram using the corrected pitch ratio J1′ and pitch angle 1map and power factor.

[0073] Step 4: Correct the installation effect of the front propeller fan efficiency.

[0074]

[0075] Among them, C Dap , C DTa , C DFu and C DNa Respectively represent the drag coefficients of the aircraft wing, tail, fuselage and engine nacelle, S ap , S Ta , S Fu and S Na are the cross-sectional areas of the aircraft wing, tail, fuselage and engine nacelle in the propeller slipstream region, η1map and η 1real They are the characteristic diagram efficiency and actual efficiency of the front propeller fan respectively.

[0076] Step 5: First, according to the power coefficient obtained in step 3 and the actual efficiency η of the front propeller fan obtained in step 4, 1real Calculate the performance parameters of the front propeller fan, namely power P1, thrust T1 and torque Q1;

[0077] Then, calculate the self-induced axial velocity V of the front propeller ind11 and the angular velocity ω ind11 .

[0078]

[0079]

[0080] Where ρ is the air density, R 1h is the hub radius of the front propeller.

[0081] Step 6: Calculate the mutual induced axial velocity V of the front row propeller fan to the rear row propeller fan ind12 .

[0082]

[0083] Among them, Z 12 The distance between the front and rear rows of propeller fans.

[0084] Step seven, calculate the actual inlet axial velocity V2 and pitch ratio J2 of the rear-row propeller fan.

[0085] V2=V0+V ind12

[0086] J2=V2 / ((N2+ω ind12 / 2π)·2R2)

[0087] Among them, R2 is the radius of the rear propeller fan, and N2 is the speed of the rear propeller fan.

[0088] Step 8: Calculate the mutual induced circumferential angular velocity ω of the front row propeller fan to the rear row propeller fan ind12 .

[0089]

[0090] Among them, A1 is the flow area of ​​the front propeller fan, K1 is the correction coefficient, R 2h is the hub radius of the rear propeller fan.

[0091] Step nine, make installation effect correction for the rear-row propeller pitch ratio.

[0092]

[0093] Among them, D2 is the diameter of the rear propeller fan.

[0094] Step 10: The efficiency η of the rear propeller fan is obtained by interpolating the corrected pitch ratio J2′ and the pitch angle from the characteristic diagram. 2map and power factor parameters.

[0095] Step 11: Correct the efficiency of the rear propeller fans for installation effects.

[0096]

[0097] Among them, η 2map and η 2real They are the characteristic diagram efficiency and actual efficiency of the rear propeller fan respectively.

[0098] Step 12: Calculate the performance parameters of the rear propeller fan, such as power P2, thrust T2, and torque Q2, as well as the self-induced axial speed V of the rear propeller fan. ind22 and the angular velocity ω ind22 .

[0099]

[0100]

[0101] Step 12: Calculate the mutual induced axial velocity V of the rear propeller fan to the front propeller fan ind21 and the angular velocity ω ind21 .

[0102]

[0103]

[0104] Among them, A2 is the flow area of ​​the rear propeller fan, and K2 is the correction coefficient.

[0105] Step 13: Determine the calculated mutual induced axial velocity V of the rear row propeller fan to the front row propeller fan ind21 and the angular velocity ω ind21 Is the value consistent with the initial guess? If not, iterate until convergence and calculation is completed.

[0106] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for calculating the performance of a counter-rotating propeller fan considering the installation effect, characterized in that The specific steps are as follows: Step 1: Given the axial mutual induced velocity V of the rear propeller fan to the front propeller fan ind21 and the circumferential mutual induced velocity ω ind21 The initial guess value V′ ind21 and ω′ ind21 ; And calculate the front row propeller fan inlet conditions, that is, the actual inlet axial speed V1 and pitch ratio J1 of the front row propeller fan; Step 2: Correct the installation effect of the front row propeller pitch ratio J1. The formula is: Among them, S Na is the cross-sectional area of ​​the engine nacelle in the propeller slipstream area, D1 is the diameter of the front row propeller fan; Step 3: Interpolate the efficiency η of the front propeller fan from the characteristic diagram using the corrected pitch ratio J1′ and pitch angle 1map and power factor; Step 4: Correct the front propeller fan efficiency for installation effects using the formula: Among them, C Dap , C DTa , C DFu and C DNa Respectively represent the drag coefficients of the aircraft wing, tail, fuselage and engine nacelle, S ap , S Ta , S Fu and S Na are the cross-sectional areas of the aircraft wing, tail, fuselage and engine nacelle in the propeller slipstream region, η 1map and η 1real They are the characteristic diagram efficiency and actual efficiency of the front propeller fan respectively; Step 5: Calculate the self-induced axial velocity V of the front propeller ind11 and the angular velocity ω ind11 ; Step 6: Calculate the mutual induced axial velocity V of the front propeller fan on the rear propeller fan ind12 ; Step 7: Calculate the actual inlet axial velocity V2 and pitch ratio J2 of the rear propeller fan; Step 8: Calculate the mutual induced circumferential angular velocity ω of the front propeller fan to the rear propeller fan ind12 , the formula is: Among them, A1 is the flow area of ​​the front row propeller fan, R1 is the radius of the front row propeller fan, K1 is the correction coefficient, R 2h is the hub radius of the rear propeller fan; Step 9: Correct the installation effect of the rear propeller pitch ratio using the formula: Wherein, D2 is the diameter of the rear propeller fan; Step 10: The efficiency η of the rear propeller fan is obtained by interpolating the corrected pitch ratio J2′ and the pitch angle from the characteristic diagram. 2map and power factor; Step 11: Correct the rear propeller fan efficiency for installation effects using the formula: Among them, η 2map and η 2real They are the characteristic diagram efficiency and actual efficiency of the rear propeller fan respectively; Step 12: Calculate the self-induced axial velocity V of the rear propeller fan ind22 and the angular velocity ω ind22 ; Step 13: Calculate the mutual induced axial velocity V of the rear propeller fan on the front propeller fan ind21 and the angular velocity ω ind21 , the formula is: Among them, A2 is the flow area of ​​the rear propeller fan, and K2 is the correction coefficient; Step 14: Determine the calculated mutual induced axial velocity V of the rear propeller fan on the front propeller fan ind21 , circumferential angular velocity ω ind21 Is it consistent with the initial guess? If not, iterate until convergence to complete the calculation.

2. A method for calculating the performance of a counter-rotating propeller fan considering installation effects according to claim 1, characterized in that: In step 1, the formula for calculating the actual inlet axial velocity V1 and pitch ratio J1 of the front row propeller fan is: V1=V0+V′ ind21 J1=V1 / ((N1+ω′ ind21 / 2π)·2R1) Wherein, V0 is the free flow velocity, R1 is the radius of the front row propeller, N1 is the speed of the front row propeller, and π is a constant.

3. A method for calculating the performance of a counter-rotating propeller fan considering installation effects according to claim 2, characterized in that: In step 5, firstly, the power coefficient obtained in step 3 and the actual efficiency η of the front propeller fan obtained in step 4 are calculated. 1real Calculate the performance parameters of the front propeller fan, namely power P1, thrust T1 and torque Q1; Then, calculate the self-induced axial velocity V of the front propeller ind11 and the angular velocity ω ind11 , the formula is as follows: Where ρ is the air density, R 1h is the hub radius of the front propeller.

4. The method for calculating the performance of a counter-rotating propeller fan considering installation effects according to claim 3, characterized in that: In step 6, the mutual induced axial velocity V of the front row propeller fan to the rear row propeller fan is calculated. ind12 The formula is: Among them, Z 12 It is the distance between the front and rear rows of propeller fans.

5. The method for calculating the performance of a counter-rotating propeller fan considering installation effects according to claim 4, characterized in that: In step 7, the actual inlet axial velocity V2 and pitch ratio J2 of the rear-row propeller fan are calculated, and the formulas are: V2=V0+V ind12 J2=V2 / ((N2+ω ind12 / 2π)·2R2) Among them, R2 is the radius of the rear propeller fan, and N2 is the speed of the rear propeller fan.

6. According to claim 5, a method for calculating the performance of a counter-rotating propeller fan taking into account installation effects is characterized in that: In step 12, firstly, the power coefficient obtained in step 10 and the actual efficiency η of the rear propeller fan obtained in step 11 are calculated. 2real Calculate the performance parameters of the front propeller fan, namely power P2, thrust T2 and torque Q2; Then, calculate the self-induced axial velocity V of the rear propeller fan ind22 and the angular velocity ω ind22 , the formula is:

Images