The boundary layer detachment limits compact power plants' operation at moderate Reynolds number in adverse pressure conditions. Flow detachment is promoted by the lack of momentum in the near-wall region when exposed to adverse pressure gradients. Transient flows or periodic flow perturbations may delay or prevent the flow detachment. The present investigation experimentally analyzes the behavior of separated flows based on an ad-hoc wall-mounted hump. The near wall flow region detachment and recirculated flow evolution under sudden flow release were experimentally characterized. The extension of the separated region and its dynamic development were monitored through surface pressure, temperature measurements, and hot-wire traverses. Comparing the 3D hump performance during steady state experiments against sudden flow acceleration runs, we report for the first time the temporal response of a diffusive passage exposed to a sudden flow acceleration and the impact of the acceleration on the boundary layer detachment. Due to the sudden flow release, the near-wall region can overcome the adverse pressure gradient. However, as the flow acceleration dilutes, the boundary layer detaches, and the recirculated flow region develops. The comparison of experimental results against 3D transient Computational Fluid Dynamics simulations, using the standard gas turbine industry approach, demonstrates the ability of Unsteady Reynolds Averaged Navier-Stokes models to predict the dynamic performance of this phenomenon.

在不利的压力条件下，边界层的分离限制了紧凑型发电厂在中等雷诺数下的运行。当暴露于不利的压力梯度时，近壁区域中动量的缺乏促进了流动的分离。瞬态流量或周期性流量扰动可能会延迟或阻止流量分离。本研究实验性地分析了基于临时壁挂式驼峰的分离流的行为。实验上表征了突然释放时的近壁流动区域分离和再循环流动演变。通过表面压力，温度测量和热线遍历来监视分离区域的扩展及其动态发展。比较稳态实验期间针对突然的流量加速运行的3D驼峰性能，我们首次报告了扩散通道在突然的流动加速作用下的时间响应以及该加速作用对边界层脱离的影响。由于突然的流量释放，近壁区域可以克服不利的压力梯度。但是，随着流动加速度的减小，边界层分离，并且形成了回流区域。使用标准燃气轮机行业方法将实验结果与3D瞬态计算流体动力学仿真进行比较，证明了非稳态雷诺平均Navier-Stokes模型能够预测此现象的动态性能。由于突然的流量释放，近壁区域可以克服不利的压力梯度。但是，随着流动加速度的减小，边界层分离，并且形成了回流区域。使用标准燃气轮机行业方法将实验结果与3D瞬态计算流体动力学仿真进行比较，证明了非稳态雷诺平均Navier-Stokes模型能够预测此现象的动态性能。由于突然的流量释放，近壁区域可以克服不利的压力梯度。但是，随着流动加速度的减小，边界层分离，并且形成了回流区域。使用标准燃气轮机行业方法将实验结果与3D瞬态计算流体动力学仿真进行比较，证明了非稳态雷诺平均Navier-Stokes模型能够预测此现象的动态性能。