Unsteady side wall flows and heat transfer in a linear turbine cascade

目前在涡轮增压器中增加压力比、减少叶片数、减小展弦比、强部分负荷操作等的努力导致侧壁附近的流动对整个发动机性能的影响越来越大。特别是工作范围，损失和传热受到这些流量的影响。虽然几十年来一直在研究，但其发生机制尚未完全了解。因此，当前的技术进步强烈要求开展充分的基础研究活动。这一缺陷将由德累斯顿工业大学、慕尼黑大学和波鸿大学的四个研究小组联合研究，通过精心协调的模拟和实验产生相关结果。除了研究传热和开发方法工具外，该联合计划的主要目标是详细分析系统旋转的影响。因此，将研究和比较一些特别规划和调整的构型。在联邦武装部队慕尼黑大学喷气推进研究所项目部分（TV 3）的框架内，将分析低压涡轮机叶栅中的端壁流动和传热。非定常端壁流的一系列研究方面包括端壁边界层、马蹄涡的形成、对端壁附近吸力面转捩的影响、端壁区域的损失产生、端壁和叶片表面的传热及其对潜在冷却方法的影响。为了产生更真实的端壁流，将在高速叶栅风洞中采用一种新的改进装置，其特点是增加了一个插入端壁，这是获得显著结果的一个关键因素。实验将利用多种具有高空间分辨率（PIV）、高时间分辨率（CTA、Kulite）以及表面测量（TSP、Thermo-LC、Shear-LC）的流量测量方法进行。实验研究将得到数值模拟（URANS）的支持，并使用流场求解器TRACE进行高保真热通量建模。研究项目部分的科学目标是提高对周期性非定常来流与端壁流动、端壁边界层和传热的相互作用机制的理解，以及评估RANS方法预测这些流动现象的能力。此外，与项目合作伙伴（特别是TV 4）的调查结果的比较提供了关于线性叶栅和轴流式涡轮机中流动现象的相似性和差异性的信息。

Current efforts in turbomachinery to increase pressure ratio, reduce blade count, decrease the aspect ratio, intense part load operation, etc. lead to increasing influence of flows near the side walls on the overall engine performance. Especially the operating range, losses and heat transfer are influenced by these flows. The occurring mechanisms are not fully understood although being investigated since decades. Thus the current technological progress strongly requests adequate basic research activity. This deficit will be addressed by a joint research program of four research groups at TU Dresden, UniBw München und RU Bochum, by carefully coordinated simulations and experiments to produce relevant results. Beside the investigation of heat transfer and the development of methodical tools a major goal of this joint program is the detailed analysis of the effect of system rotation. Therefore a number of specially planed and adjusted configurations will be investigated and compared with each other.Within the framework of the project part (TV3) at the Institute of Jet Propulsion of the University of the Federal Armed Forces Munich, the endwall flow and heat transfer will be analyzed in a low pressure turbine cascade. The array of investigated aspects of the unsteady endwall flow include the endwall boundary layer, the formation of the horse shoe vortex, influence on suction surface transition near the endwall, loss production in the endwall region, as well as heat transfer to the endwall and blade surfaces and its effect on potential cooling methods. A new and improved setup, featuring an additional inserted endwall, will be implemented in the High Speed Cascade Wind Tunnel in order to produce more realistic endwall flow, which is a critical factor in attaining significant results. The experiments will be conducted utilizing a multitude of flow measurement methods with high spatial resolution (PIV), high time resolution (CTA, Kulite), as well as surface measurements (TSP, Thermo-LC, Shear-LC). The experimental investigations will be supported by numerical simulations (URANS) with high fidelity heat flux modeling, using the flow solver TRACE. The scientific goal of the research project part is to improve the understanding of the interaction mechanisms of the periodically unsteady inflow with the endwall flow, the endwall boundary layer and heat transfer as well as to evaluate the capabilities of the RANS method to predict these flow phenomena. Furthermore, comparisons of the investigation results with the project partners (especially TV4) provide information regarding the similarities and differences of flow phenomena in linear cascades and axial turbines.