Separation Control by Slot Jet in a Critically Loaded Compressor Cascade

Abstract

Separation in compressor cascade triggers flow loss and instability. This paper presents a passive flow control method by introducing a slot into the blade. The slot induces self-adapted jet, while the jet flow is used to suppress cascade’s separation. To study the flow control effect, experiments were conducted and flow field details were given by validated numerical simulations. The results show that a well-designed slot carries adequate jet airflow from pressure side (PS) to suction side (SS) due to the great pressure fall between the two sides. The jet airflow delays suction side separation within specific incidence angles, so the performance of cascade achieves considerable improvements. It enables to be concluded that the slot carries jet flow to SS separation zone, and then the self-adapted jet flow re-energizes low momentum fluid and suppresses vortices in the separation which are negative to the cascade flow.

Experimental investigation on separation control by slot jet in highly loaded compressor cascade

“…A novel arc slot is designed in this paper to replace the previous linear slot. [19][20][21][22][23] The reason is that the arc slot has the potential to reduce the extra flow loss caused by the shape geometry in the linear slot. The comparison of the linear slot and the arc slot is presented in Figure 1.…”

“…The comparison of the linear slot and the arc slot is presented in Figure 1. The slot parameter selection is on the basis of the conclusions of the references [19][20][21][22][23] and is validated by extensive numerical simulations. Figure 1 shows the cascade and the slot parameter illustrations.…”

“…The results show that it can delay trailing edge separation and subsequent stall to higher angles of attack, without the need for any active energy input and without significant drag penalty. The slot jet approach was initially introduced to the compressor cascade by Wang et al [19][20][21][22] They performed a series of parametric investigations to study the impacts of the slot location, the slot inflow and outflow angle, and the shapes for better jets. Ramzi and Abderrahmane 23 analyzed the effects of location, width, and slope of slots, acquiring 28% reduction in loss coefficient and 5 increase in flow turning angle in a conventional load cascade.…”

Synthetic Separation Control Using Vortex Generator and Slot Jet in a High Load Compressor Cascade

“…The first type is actuator, such as jets (Hecklau et al 2011), plasma actuation (Akcayoz et al 2015), and suction (Guo et al 2013), et al Actuators always need external input devices and additional energy consumption. The second type is geometric shape, such as end-wall contouring (Varpe et al 2015), end-wall fences (Govardhan et al 2012), vortex generator (Pesteil et al 2010;Hergt et al 2006Hergt et al , 2013Wu et al 2016), slot jet (Wu et al 2013(Wu et al , 2014Hu et al 2016Hu et al , 2017, et al Geometric shape usually operates by some geometric design which induces some special flow behaviors and improve the flow field. The geometric shape applications usually need no additional input devices.…”

“…A slot jet approach was developed to reduce the separation in compressor blade by Ramzi (2013), Wu et al (2013Wu et al ( , 2014 and Hu et al (2016Hu et al ( , 2017. A slot which connected the flow field between pressure side and suction side was inserted into the blade.…”