基于壁模化大涡数值模拟的喷水推进泵内湍流运动特性分析

doi:10.12382/bgxb.2024.0850

摘要/Abstract

摘要：

尺度解析类数值模拟方法具有很高的非定常流动预报潜力,其中壁模化大涡数值模拟(Wall-modeled Large-eddy Simulation,WMLES)方法在高雷诺数下具有适用范围广、计算成本较低等优势但在喷水推进泵的数值模拟中应用有限。采用基于湍流场特征尺度分析的WMLES方法进行原型喷水推进泵及改型喷水推进泵的泵内流场数值模拟并与试验数据进行对比。结果显示,WMLES预报的两型喷水推进泵的扬程及转矩等外特性特征都与试验数据吻合极好。从泵内湍流运动特性分析的角度,WMLES方法再现了传统RANS(Reynolds-Averaged Navier-Stokes)方法难以获得的导边马蹄涡、随边角涡、叶梢集中涡、间隙泄漏涡等精细流动特征。在相同流量系数下,改型泵的马蹄涡、角涡等二次流强度明显小于原型泵,改型泵的平均极限流线也明显更为光顺,更低的能量耗散使得改型泵的工作效率相比原型泵有明显提升。分析结果证明,基于湍流场特征尺度分析的WMLES方法可用于喷水推进泵的外特性及泵内湍流运动特性的有效预报,为喷水推进泵的改进设计提供了有力的数据支撑。

关键词: 大涡数值模拟, 壁模化方法, 湍流特征尺度, 喷水推进泵, 非定常流

Abstract:

Scale-resolving simulations are potential for accurate predictions of unsteady flows.Wall-modeled large-eddy simulation (WMLES)has the advantages of wide application and relatively low computational cost.However,the application of WMLES to the turbulent flow in water-jet pump is limited.The WMLES based on the analysis of turbulent length scales is applied to simulate the flow fields in a prototype pump and a modified pump,and the simulated results are compared to the experimental results.The head rise and torque coefficients predicted by the WMLES agreed well with the experimental data.The analysis of the turbulent properties of flows in the pumps demonstrate that the WMLES is capable of reproducing the horseshoe vortices,corner vortices,tip concentrating vortices and tip leakage vortices that are difficult for the conventional Reynolds-Averaged Navier-Stokes (RANS)method to reproduce.The horseshoe and corner vortices of the modified pump are much weaker than those of the prototype pump,and the limiting streamlines of the modified pump are smoother that those of the prototype pump.The lower dissipation of energy caused by the weaker vortices led to the higher efficiency of the modified pump.The results demonstrated that the WMLES based on the analysis of turbulent length scales could be effectively applied to predict the performance and turbulent properties of flow in the water-jet pump,which can provide the data support for the improvement of water-jet pump.

Key words: large-eddy simulation, wall modeling method, turbulent length scale, water-jet pump, unsteady flow

许辉, 陈作钢, 蔡佑林. 基于壁模化大涡数值模拟的喷水推进泵内湍流运动特性分析[J]. 兵工学报, 2024, 45(S2): 55-64.

XU Hui, CHEN Zuogang, CAI Youlin. Analysis of the Turbulent Properties of Flow in Water-jet Pump Based on Wall-modeled Large-eddy Simulations[J]. Acta Armamentarii, 2024, 45(S2): 55-64.

图/表 17

图1 均匀各向同性湍流的湍动能能谱及湍动能耗散谱示意图

Fig.1 Schametic diagram of the turbulent energy spectrum and dissipation spectrum for homogeneous isotropic turbulence

图2 基于湍流场特征尺度分析的WMLES计算流程

Fig.2 Workflow of the wall-modeled large-eddy simulation based on the analysis of turbulent length scales

图3 原型(左)及改型(右)喷水推进泵几何模型示意图

Fig.3 Geometrical models of the prototype pump (left)and modified pump (right)

图4 喷水推进泵计算域

Fig.4 Computational domain of flow in the water-jet pump

图5 泵体上下游扬程测压截面

Fig.5 Upstream and downstream sections of pump for pressure monitoring

图6 喷水推进泵内湍流特征尺度与及过滤尺度对比

Fig.6 Comparison of the turbulent length scale and the filtering length scale in the pump

图7 泵体表面及流道中纵剖面网格分布

Fig.7 Distribution of the meshes on the pump surfaces and longitudinal section

表1 原型喷水推进泵RANS计算结果与试验数据对比

Table 1 Comparison of the experimental (EFD)and RANS results of the prototype pump

K_Q	K_H(EFD)	K_H(RANS)	e(EFD)/%	K_M(EFD)	K_M(RANS)	e(LES)/%	η(EFD)	η(RANS)
0.7279	2.2355	2.294	2.62	0.3047	0.3018	-0.97	0.8498	0.8806
0.6927	2.3716	2.430	2.48	0.3062	0.3038	-0.80	0.8538	0.8820
0.6741	2.4275	2.488	2.49	0.3065	0.3033	-1.06	0.8497	0.8802
0.6451	2.5077	2.580	2.87	0.3060	0.3034	-0.86	0.8412	0.8729
0.6160	2.5617	2.625	2.49	0.3032	0.3017	-0.50	0.8282	0.8531
0.5831	2.5972	2.629	1.22	0.3009	0.2989	-0.66	0.8010	0.8161

表2 原型喷水推进泵LES计算结果与试验数据对比

Table 2 Comparison of the experimental (EFD)and LES results of the prototype pump

K_Q	K_H(EFD)	K_H(LES)	e(EFD)/%	K_M(EFD)	K_M(LES)	e(LES)/%	η(EFD)	η(LES)
0.7279	2.2355	2.2502	0.66	0.3047	0.3091	1.43	0.8498	0.8433
0.6927	2.3716	2.3919	0.86	0.3062	0.3098	1.16	0.8538	0.8512
0.6741	2.4275	2.4410	0.56	0.3065	0.3091	0.85	0.8497	0.8472
0.6451	2.5077	2.5339	1.04	0.3060	0.3078	0.56	0.8412	0.8453
0.6160	2.5617	2.6008	1.53	0.3032	0.3051	0.60	0.8282	0.8359
0.5831	2.5972	2.6523	2.12	0.3009	0.3006	-0.10	0.8010	0.8188

表3 改型喷水推进泵LES计算结果与试验数据对比

Table 3 Comparison of the experimental (EFD)and LES results of the modified pump

K_Q	K_H(EFD)	K_H(LES)	e(EFD)/%	K_M(EFD)	K_M(LES)	e(LES)/%	η(EFD)	η(LES)
0.6741	2.7575	2.7743	0.61	0.3318	0.3306	-0.37	0.8954	0.9007

图8 原型与改型喷水推进泵计算结果中基于q准则捕获的叶轮导边叶根发展的马蹄涡

Fig.8 Representations of the horseshoe vortices induced by the roots of impeller leading edges of the prototype pump and modified pump by means of the q criterion

图9 原型(左)与改型(右)喷水推进泵计算结果中基于q准则捕获的叶根发展的马蹄涡

Fig.9 Representations of the horseshoe vortices induced by the roots of impellers of the prototype pump (left)and modified pump (right)by means of the q criterion

图10 原型(左)与改型(右)喷水推进泵计算结果中基于q准则捕获的叶轮叶梢集中涡

Fig.10 Representations of the concentrating vortices near the impeller tips of the prototype pump (left)and modified pump (right)by means of the q criterion

图11 原型(上)与改型(下)喷水推进泵叶轮压力面平均极限流线分布对比图

Fig.11 Comparison of the time-averaged limiting streamlines on the pressure surfaces of the prototype pump (top)and modified pump (bottom)

图12 原型(上)与改型(下)喷水推进泵叶轮吸力面平均极限流线分布对比图

Fig.12 Comparison of the time-averaged limiting streamlines on the suction surfaces of the prototype pump (top)and modified pump (bottom)

图13 原型(左)及改型(右)喷水推进泵基于q准则捕获的推进泵导叶角涡特性对比

Fig.13 Comparison of the corner vortices induced by the diffusers of the prototype pump (left)and modified pump (right)by means of the q criterion

图14 原型(左)及改型(右)喷水推进泵导叶表面平均极限流线对比

Fig.14 Comparison of the time-averaged limiting streamlines on the diffuser surfaces of the prototype pump (left)and modified pump (right)

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