Diaphragmless shock tube with multiple air-operated valves

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K. Inokuma, T. Maeda, T. Watanabe, K. Nagata
Diaphragmless shock tube with multiple air-operated valves
Experiments in Fluids, 63 121 2022

This article may be found at https://doi.org/10.1007/s00348-022-03473-y or on ResearchGate.

Accepted manuscript is available here. 
This version is free to view and download for private research and study only. 

Abstract

In this study, a novel diaphragmless shock tube driven by a driver valve system consisting of multiple air-operated valves was developed. The novel shock tube can generate shock waves with high repeatability, which are required for statistical investigations of shock waves. The main valve of the driver valve system is opened by decompressing the air in the sub-high-pressure room behind the main valve using “sub-valves”; this results in a shock wave formation inside the shock tube. Three different driver valves (driver valve with “a single solenoid sub-valve,” “a single air-operated sub valve,” and “three air-operated sub-valves”) were developed. For each of the three driver valves, the overpressure waveforms of the shock waves were measured with pressure sensors installed on the inner wall of the shock tube and in front of the open end of the shock tube. Furthermore, the shock Mach number was calculated from the overpressure behind the shock waves. The shock Mach number was the largest for the driver valve with the air-operated sub-valve(s). The standard deviation of the peak overpressure fluctuations of the shock waves ejected from the open end of the shock tube was the smallest for the driver valve with the three air-operated sub valves. From the results, it was observed that the quick opening time of the main valve realized by the multiple sub-valves increased the shock wave strength and improved the repeatability of the shock wave generation.

日本語訳 (DeepL翻訳)

複数の空気駆動バルブを持つ隔膜レス衝撃波管

本研究では，複数の空気作動バルブで構成されるドライバーバルブ系で駆動する新しい隔膜レス衝撃波管 を開発した。この新型衝撃波管は、衝撃波の統計的調査に必要とされる高い再現性で衝撃波を発生させることができる。ドライバーバルブシステムのメインバルブは、メインバルブ後方のサブ高圧室内の空気を「サブバルブ」で減圧することで開かれ、その結果、衝撃波管内に衝撃波が形成さ れる。今回、3種類のドライバーバルブ（「電磁サブバルブ1個」「空圧サブバルブ1個」「空圧サブバルブ3個」のドライバーバルブ）を開発した。3つの駆動弁それぞれについて，衝撃波管の内壁と開放端の前に設置した圧力センサで衝撃波の過剰圧波形を測定した．さらに、衝撃波の背後の過剰圧から、衝撃マッハ数を算出した。衝撃マッハ数は，駆動弁と空気作動副弁の組み合わせで最も大きくなった。また，衝撃波管の開放端から噴出する衝撃波のピーク過圧変動の標準偏差は，3つの空圧サブバルブを備えたドライババルブで最も小さくなった。この結果から，複数のサブバルブによって実現される主弁の迅速な開弁は，衝撃波の強度を高め，衝撃波発生の再現性を向上させることが確認された。

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