Effect of load distribution of the front and rear blades on the flow characteristics of highly loaded subsonic compressor tandem cascades

The overall load distribution of the front blade (FB) and rear blade (RB) is a main factor affecting the tandem cascade performance, and camber ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> ) and chord ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> ) are the key configuration parameters related to the load distribution. To supplement the principle of tandem cascade design, the current paper systematically studies the influence mechanisms of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> on the flow characteristics. It is found that larger <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> or smaller <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> can improve the flow behavior of FB so that get a better performance at positive incidence angle, while it will deteriorate that at negative incidence angle. In fact, different <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> cause the change in surface curvature , which is considered to have a significant impact on the flow behavior. Therefore, this paper proposes mean curvature ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> <mml:mo>/</mml:mo> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> ) to replace <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> for its better control effect on the performance at various incidence, and a general design criterion is obtained based on a large amount of tandem cascades with different configurations. The results show that <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> <mml:mo>/</mml:mo> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> between two and four can balance the performance comprehensively at various conditions, and larger <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mi>R</mml:mi> <mml:mo>/</mml:mo> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> or smaller <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>R</mml:mi> </mml:mrow> </mml:math> can achieve better performance at highly loaded condition, while that is opposite for lower load.